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Charged-particle angular correlations in XeXe collisions at s N N = 5.44 TeV

October 2019
Physical Review C 100(4)

DOI:10.1103/PhysRevC.100.044902

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Azimuthal correlations of charged particles in xenon-xenon collisions at a center-of-mass energy per nucleon pair of sNN=5.44 TeV are studied. The data were collected by the CMS experiment at the LHC with a total integrated luminosity of 3.42μb−1. The collective motion of the system formed in the collision is parametrized by a Fourier expansion of the azimuthal particle density distribution. The azimuthal anisotropy coefficients v2, v3, and v4 are obtained by the scalar-product, two-particle correlation, and multiparticle correlation methods. Within a hydrodynamic picture, these methods have different sensitivities to noncollective and fluctuation effects. The dependence of the Fourier coefficients on the size of the colliding system is explored by comparing the xenon-xenon results with equivalent lead-lead data. Model calculations that include initial-state fluctuation effects are also compared to the experimental results. The observed angular correlations provide new constraints on the hydrodynamic description of heavy ion collisions.

The v 4 coefficients, based on the different analysis techniques, as functions of transverse momentum and in bins of centrality, from the 5% most central (top left) to 60-70% centrality (bottom right). The results for the two-particle correlations correspond to the range |η| < 2.4, while the scalar-product results are for |η| < 0.8. The bars and the shaded boxes represent statistical and systematic uncertainties, respectively.

…

Centrality dependence of the spectrum-weighted v 2 , v 3 , and v 4 flow harmonics with 0.3 < p T < 3.0 GeV/c. The v 2 results are shown for two-, four-, six-, and eight-particle correlations (left panel). The v 3 results are shown for two-and four-particle correlations (middle panel), while the v 4 values are presented for two-particle correlations technique, only. The solid curve in each panel is the IP-GLASMA+MUSIC+UrQMD prediction for v n {2}. The shaded boxes represent systematic uncertainties.

…

Comparison of the v 3 results measured with two-particle correlations from two different systems, XeXe collisions at √ s NN = 5.44 TeV and PbPb collisions at 5.02 TeV, shown as a function of p T in 11 centrality bins. The bars (smaller than the marker size) and the shaded boxes represent statistical and systematic uncertainties, respectively.

…

Comparison of the v 4 results measured with two-particle correlations from two different systems, XeXe collisions at √ s NN = 5.44 TeV and PbPb collisions at 5.02 TeV, shown as a function of p T in 11 centrality bins. The bars and the shaded boxes represent statistical and systematic uncertainties, respectively.

…

Ratios of the v 2 , v 3 , and v 4 harmonic coefficients from two-particle correlations in XeXe and PbPb collisions as functions of p T in 11 centrality bins. The bars and the shaded boxes represent statistical and systematic uncertainties, respectively.

…

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PHYSICAL REVIEW C 100, 044902 (2019)

Charged-particle angular correlations in XeXe collisions at √sNN =5.44 TeV

A. M. Sirunyan et al.∗

(CMS Collaboration)

(Received 23 January 2019; published 3 October 2019)

Azimuthal correlations of charged particles in xenon-xenon collisions at a center-of-mass energy per nucleon

pair of √sNN =5.44 TeV are studied. The data were collected by the CMS experiment at the LHC with a total

integrated luminosity of 3.42 μb−1. The collective motion of the system formed in the collision is parametrized

by a Fourier expansion of the azimuthal particle density distribution. The azimuthal anisotropy coefﬁcients v2,v3,

and v4are obtained by the scalar-product, two-particle correlation, and multiparticle correlation methods. Within

a hydrodynamic picture, these methods have different sensitivities to noncollective and ﬂuctuation effects. The

dependence of the Fourier coefﬁcients on the size of the colliding system is explored by comparing the xenon-

xenon results with equivalent lead-lead data. Model calculations that include initial-state ﬂuctuation effects are

also compared to the experimental results. The observed angular correlations provide new constraints on the

hydrodynamic description of heavy ion collisions.

DOI: 10.1103/PhysRevC.100.044902

I. INTRODUCTION

At sufﬁciently high temperatures or densities, lattice quan-

tum chromodynamics predicts a transition from ordinary

hadronic matter to a state of deconﬁned quarks and gluons, the

so-called quark gluon plasma (QGP) (see, e.g., Ref. [1]). The

QGP state can be reached through relativistic heavy ion col-

lisions, where the collective behavior of the created medium

manifests itself in azimuthal correlations among the emitted

particles. These correlations have been studied in gold-gold

collisions at the BNL RHIC [2–5], lead-lead (PbPb) collisions

at the CERN LHC [6–8], as well as in collisions involving

lighter nuclei, such as the copper-copper system studied at

RHIC [9,10]. More recently, collective behavior similar to that

observed in collisions of heavy nuclei has also been found

in high-multiplicity events produced in the proton-lead (pPb)

system, and in proton-proton (pp) collisions [11–14]. The re-

sults from these small systems raise the question as to how the

size of the colliding system affects the onset of QGP forma-

tion. Measurements from xenon-xenon (XeXe) collisions, as

presented here, bridge the gap between the small (pp and pPb)

and large (PbPb) systems previously studied at LHC energies.

Anisotropic ﬂow can be characterized by a Fourier expan-

sion [15–17],

2π

dφ=1+∞



n=1

2vncos[n(φ−n)],(1)

where dN/dφis the azimuthal particle density and φis the

particle azimuthal angle with respect to a reference angle n.

∗Full author list given at the end of the article.

Published by the American Physical Society under the terms of the

Creative Commons Attribution 4.0 International license. Further

distribution of this work must maintain attribution to the author(s)

and the published article’s title, journal citation, and DOI. Funded

by SCOAP3.

Different reference angles can be deﬁned. The “participant

plane” angle is the direction of the semiminor axis of the

region perpendicular to the beam direction spanned by the

nucleons that undergo a primary interaction. The “event-

plane” angle is deﬁned by the direction perpendicular to the

beam direction of the maximum outgoing particle density. In

this paper the measured anisotropies are expressed in terms of

the event-plane reference angle. Averaged over many events,

the anisotropies measured with respect to the event plane are

expected to be similar to those that would be obtained if it

were possible to determine the actual participant plane.

The magnitude of the azimuthal anisotropy is characterized

by the Fourier coefﬁcients vn. The second- and third-order

Fourier coefﬁcients are referred to as “elliptic” (v2) and

“triangular” (v3) ﬂow, respectively. The former reﬂects the

lenticular shape of the collision overlap region, as well as

initial-state ﬂuctuations in the positions of nucleons at the

moment of impact [18]. The latter is largely a consequence

of ﬂuctuations. While the v2and v3harmonics are believed

to reﬂect the initial-state geometry [19], for n4 the ﬂow

harmonics are also strongly affected by the dynamics of the

system expansion. Hence, studying both the lower and higher

ﬂow harmonics is important for understanding the medium

created in heavy ion collisions.

This analysis presents measurements of the charged-

particle collective ﬂow in XeXe collisions at a center-of-mass

energy per nucleon pair of √sNN =5.44 TeV. The results

are shown as functions of transverse momentum, pT,forthe

pseudorapidity region |η|<2.4 and for different collision

overlap geometries. Spectrum-weighted values with 0.3<

pT<3.0GeV/c, with the efﬁciency-corrected yield in each

pTinterval used as the weight, are also presented. The Fourier

coefﬁcients v2,v3, and v4are obtained by two-particle cor-

relations (vn{2}), the scalar-product method (vn{SP}), and

multiparticle cumulant analyses (vn{m},m=4, 6, and 8).

Event-by-event ﬂuctuations in the spatial overlap geom-

etry lead to method-dependent differences in the extracted

A. M. SIRUNYAN et al. PHYSICAL REVIEW C 100, 044902 (2019)

vnvalues [20,21]. The ﬂuctuations cause an increase in the

deduced vnvalues found using two-particle correlations and

the scalar-product method, as compared to the corresponding

participant plane value, while the four-particle cumulant vn

results are decreased. For ﬂuctuations that follow a two-

dimensional Gaussian behavior, the ﬂow harmonics based

on more than four particles are expected to be the same

as the four-particle correlations results. Deviations from this

common behavior can be used to estimate the higher-order

moments of the ﬂuctuation distribution. Comparison of ﬂow

coefﬁcients measured by different methods probes the initial-

state conditions.

The XeXe values are compared to the results from PbPb

collisions at √sNN =5.02 TeV. The comparison with mea-

surements from different collision systems, but with similar

collision geometry, can give insight to the system size depen-

dence of the anisotropic ﬂow [22]. Theoretical predictions are

compared to the observed system size dependence of the ﬂow

harmonics. The results presented here provide new informa-

tion on the initial-state geometry and its ﬂuctuations, as well

as the system size dependence of the medium properties.

II. CMS DETECTOR

The central feature of the CMS apparatus is a supercon-

ducting solenoid of 6 m internal diameter, providing a mag-

netic ﬁeld of 3.8 T. Within the solenoid volume are a silicon

pixel and strip tracker, a lead tungstate crystal electromag-

netic calorimeter (ECAL), and a brass and scintillator hadron

calorimeter (HCAL), each composed of a barrel and two end-

cap sections. Forward calorimeters extend the pseudorapidity

coverage provided by the barrel and endcap detectors. Muons

are detected in gas-ionization chambers embedded in the steel

ﬂux-return yoke outside the solenoid. The hadron forward

(HF) calorimeter uses steel as an absorber and quartz ﬁbers

as the sensitive material. The two HF calorimeters are located

11.2 m from the interaction region, one on each end, and

together they provide coverage in the range 3.0<|η|<5.2.

These calorimeters serve as luminosity monitors, are used

to establish the event centrality, and provide the event-plane

information for the scalar-product analysis. The HF calorime-

ters are azimuthally subdivided into 20◦modular wedges and

further segmented to form 0.175 ×10◦(η ×φ)towers.

The silicon tracker measures charged particles within the

pseudorapidity range |η|<2.5. For nonisolated particles of

1<pT<10 GeV/c and |η|<1.4, the track resolutions are

typically 1.5% in pTand 25–90 (45–150) μm in the trans-

verse (longitudinal) impact parameter [23]. A more detailed

description of the CMS detector, together with a deﬁnition

of the coordinate system used and the relevant kinematic

variables, can be found in Ref. [24]. The detailed Monte Carlo

(MC) simulation of the CMS detector response is based on

GEANT4[25].

III. EVENTS AND TRACK SELECTION

Results based on data recorded by CMS during the LHC

runs with XeXe collisions at √sNN =5.44 TeV in 2017,

with an integrated luminosity of 3.42 μb−1, are compared

to similar data obtained in 2015 from PbPb collisions at

√sNN =5.02 TeV with an integrated luminosity of 26 μb−1.

In both systems, only tracks with |η|<2.4 and 0.3<pT<

10.0GeV/c are used.

For the XeXe events, a hardware level (level-1) trigger

required at least one tower of the HF calorimeters to be

above a threshold that was ﬁxed to maximize the number of

events counted, while keeping low the noise contamination

from electromagnetic scattering and from pileup (i.e., multiple

interactions in the same or neighboring bunch crossings). This

trigger also required the presence of both colliding bunches at

the interaction point. The average online pileup fraction was

0.018 per event. In addition, a high-level trigger was applied

that required at least one track in the pixel detector. Events

are further selected ofﬂine by requiring at least 3 GeV of

energy being detected in each of three HF calorimeter towers

on either side of the CMS detector and to have a reconstructed

primary vertex, containing at least two tracks, located within

15 cm of the nominal collision point along the beam axis

and within 0.2 cm in the transverse direction. In addition,

contamination from beam-gas interactions are suppressed by

applying a ﬁlter where, for each event with more than ten

tracks, at least 25% of the tracks are required to satisfy a high

purity [23] track quality criteria. The event selection efﬁciency

is 95%. The track reconstruction algorithm is similar to that

used for pp collisions [23].

For PbPb collisions, as compared to XeXe events, there

is an additional level-1 trigger requirement of a coincidence

between signals in the HF calorimeters on either side of the

CMS detector. While ofﬂine event selection is similar for

PbPb and XeXe events, for the PbPb events the ﬁlter to sup-

press beam-gas interaction is not applied and pileup contam-

ination is controlled by following the procedure outlined in

Ref. [26].

To ease the computational load for high-multiplicity cen-

tral PbPb collisions, track reconstruction for PbPb events

is done in two iterations. The ﬁrst iteration reconstructs

tracks from signals (“hits”) in the silicon pixel and strip

detectors compatible with a trajectory of pT>0.9GeV/c.

The second iteration reconstructs tracks compatible with a

trajectory of pT>0.2GeV/c using solely the pixel detector.

In the ﬁnal analysis, the ﬁrst iteration tracks with pT>

1.0GeV/c are combined with pixel-detector-only tracks with

pT<2.4GeV/c, after removing duplicates.

In this paper only tracks from primary charged particles

are considered. For the XeXe tracks and the PbPb tracks

with both silicon pixel and strip hits, the impact parameter

signiﬁcance of the tracks with respect to the primary vertex

in both the beam direction (dZ) and the transverse plane (d0)

must be less than three standard deviations, while the relative

pTuncertainty (σpT/pT) must be below 10%. In addition,

each track is required to have at least 11 hits in the tracker,

and the chi-square per degree of freedom, associated with

ﬁtting the track trajectory, normalized to the total number

of layers with hits along the trajectory, χ2/dof/layers, must

be less than 0.15. For the PbPb pixel-only tracks, it was

required that dZbe less than eight standard deviations and that

χ2/dof/layers <12.

044902-2

CHARGED-PARTICLE ANGULAR CORRELATIONS … PHYSICAL REVIEW C 100, 044902 (2019)

IV. ANALYSIS TECHNIQUES

The analysis techniques used in this study are fully de-

scribed in previous CMS publications. A two-particle corre-

lation analysis, as discussed in Refs. [27,28], is performed for

both the XeXe and PbPb data sets. In addition, scalar-product

and multiparticle cumulant analyses, as described in Ref. [29],

are done for the XeXe data.

In the two-particle correlation analyses, a charged par-

ticle from one transverse momentum interval is used as

a “trigger” particle, to be paired with all of the remain-

ing charged particles from either the same or a different

pTinterval, the “associated” particles. For a given trigger

particle, the pairing is done in bins of pseudorapidity and

azimuthal angle (η, φ ). A similar pairing between the

particles randomly chosen from two different events is done

to establish a background distribution. A Fourier analysis of

the azimuthal correlation between the trigger and associated

particles leads to VnFourier coefﬁcients, where nis the

Fourier order. If factorization is assumed, the two-particle

coefﬁcients can be expressed in terms of single-particle coefﬁ-

cients, with Vn(pTtrig,pTassoc )=vn{2}(pTtrig )vn{2}(pTassoc).

The vn(pTassoc) term is given by √Vn(pTassoc,pTassoc ),

thereby allowing vn(pTtrig) to be determined.

In order to minimize statistical uncertainties, the associated

particles are taken from a wide pTrange with large average

anisotropic ﬂow. In this analysis, 1.0<pTassoc <3.0GeV/c.

To avoid short-range, nonﬂow correlations, a pseudorapidity

gap of |η|>2 is required for the particle pairs.

The scalar-product event-plane measurements are based on

recentered ﬂow Qvectors, deﬁned as



Qn=M



wicos(nφi)−M



wicos(nφi),



wisin(nφi)−M



wisin(nφi).

Here, wiis a weight for the ith particle emitted at azimuthal

angle φi. The summations are over the number of particles M

within a given (centrality, ηrange, pTrange) analysis bin for

a given event. The averages indicated by the angular brackets

are taken over all particles in all events within each analysis

bin. These averages correspond to the recentering operation

and are needed to minimize detector acceptance effects. If the

Qvectors are presented as the corresponding complex scalars,

the ﬂow coefﬁcients are given by

vn{SP}≡ QnQ∗

nA

QnAQ∗

nBQnA Q∗

nC 

QnBQ∗

nC 

.(2)

The particles of interest are used to obtain the Qnvector, with

unit weighting (wi=1) in the sum. The subscripts A,B, and C

refer to three separate reference vectors established in differ-

ent ηregions. The product of Qnwith the QnA reference vector

correlates the particles of interest with particles detected in

the HF calorimeter (region A). For the current measurement

particles of interest with −0.8<η<0.0(0.0<η<0.8) and

within different pTranges are correlated with HF particles

in the range 3 <η<5(−5<η<−3). The products with

Qvectors Band Care used to correct for ﬁnite resolution

effects. The QnC vector corresponds to particles detected in

the HF calorimeter opposite to that used to deﬁne the QnA

vector. The QnB vector corresponds to particles measured

in the tracker with |η|<0.5. Since the vn(pT) coefﬁcients

increase with pTup to ≈3GeV/c, the choice of either pTor ET

weighting results in a better event-plane resolution than with

unit weighting. The QnA and QnC vectors use ETweighting,

whereas the QnB vector uses pTweighting [30].

The Q-cumulant method is used in this analysis to obtain

the four- (vn{4}), six- (vn{6}), and eight- (vn{8}) particle nth-

order harmonic results by correlating unique combinations of

four, six, and eight particles within each event. The method

uses a generic framework described in Ref. [31]. This frame-

work allows for a track-by-track weighting to correct for the

detector acceptance effects. A wider pseudorapidity range

with |η|<2.4 is used for the cumulant method analysis, as

compared to the scalar-product method, to reduce statistical

uncertainties.

Results are presented in ranges of collision centrality. The

centrality variable is deﬁned as a fraction of the inelastic

hadronic cross section, with 0% corresponding to full overlap

of the two colliding nuclei. The event centrality is determined

ofﬂine and is based on the total energy measured in calorime-

ters located in the forward pseudorapidity region 3 <|η|<

5. The analysis is performed in 11 centrality classes, with

intervals ranging from 0–5% to 60–70%. By comparing the

XeXe and PbPb results in given centrality ranges, similar

collision overlap geometries can be achieved, albeit with

different numbers of participants.

In comparing the XeXe and PbPb results for more periph-

eral collisions, it needs to be noted that the XeXe results can

be affected by an experimental bias introduced by the cen-

trality determination. Multiplicity ﬂuctuations in the forward

region used to determine the event centrality can reduce the

centrality resolution. Monte Carlo studies using the HYDJET

event generator indicate this bias can be as large as 5% in the

50–60% centrality range and 10% in the 60–70% range for

the vn{2}coefﬁcients. For the vn{4}coefﬁcients, the bias is

less than 5% in the 60–70% centrality range. For more central

events, the bias is found to be negligible.

V. SYSTEMATIC UNCERTAINTIES

Four different sources of systematic uncertainties are con-

sidered. To study the effect of the track selection on the ﬁnal

results, different track criteria are applied by varying the limits

for the impact parameter signiﬁcance from 2 to 5, and the

relative pTuncertainty from 5% to 10%. These variations

are found to have a 1% inﬂuence on vnresults for peripheral

collisions, increasing to 10% for the most central collisions at

the lowest pTvalues. The effect of moving the primary vertex

position along the beam axis is studied by comparing the re-

sults with events from the vertex position ranges |zvtx|<3cm

and 3 <|zvtx|<15 cm to the default range of |zvtx|<15 cm.

A 1% systematic uncertainty is attributed to this source. The

systematic uncertainty resulting from the XeXe centrality

calibration is estimated by varying the event selection criteria.

This uncertainty is largest for the most peripheral centrality

044902-3

A. M. SIRUNYAN et al. PHYSICAL REVIEW C 100, 044902 (2019)

0.05

0.1

0.15

0.2

0.25

CMS

Centrality: 0-5%

0.05

0.1

0.15

0.2

0.25 20-25%

(GeV/c)

02468

0.05

0.1

0.15

0.2

0.25 40-50%

5-10%

25-30%

(GeV/c)

02468

50-60%

10-15%

30-35%

(GeV/c)

02468

60-70%

15-20%

= 5.44 TeV

sXeXe

35-40%

(GeV/c)

02468

| > 2}ηΔ{2, |

{4}

{6}

{8}

| < 0.8η, |{SP}

| < 2.4η|

FIG. 1. Elliptic-ﬂow coefﬁcients v2based on different analysis techniques, as functions of transverse momentum and in bins of centrality,

from the 5% most central (top left) to 60–70% centrality (bottom right). The results for the two-particle and multiparticle correlations

correspond to the range |η|<2.4, while the scalar-product results are for |η|<0.8. The bars and the shaded boxes represent statistical

and systematic uncertainties, respectively.

bin, where it reaches a value of 3%. To explore the sensitivity

of the results to the MC simulations on which the efﬁciency

determinations are based, analyses using the HYDJET 1.9 [32]

event generator are done for generated tracks both before and

after the detector effects are taken into account. The results for

the two cases differ by about 2% for most centrality ranges,

but the difference increases to 10% for the most central events

and the lowest track transverse momenta, 0.3–0.4 GeV/c.

The observed differences are included as a systematic un-

certainty. The different uncertainty sources are independent

and uncorrelated, therefore the total systematic uncertainty

is obtained by combining the individual contributions in

quadrature.

VI. RESULTS

Figure 1shows the v2results, as a function of pTand in

11 centrality bins, as measured with the different techniques.

The two- and multiparticle correlation results are averaged

over the pseudorapidity range of |η|<2.4, while the scalar-

product results are based on tracks with |η|<0.8. The elliptic

ﬂow values extracted from two-particle correlations show the

same pattern as with the multiparticle correlations, but with

higher magnitudes. The difference in the results obtained

from the two different methods can be largely ascribed to

event-by-event ﬂuctuations of the v2coefﬁcient [20]. The

v2magnitude increases with pT, reaching a maximum value

of 0.21 around 3–4 GeV/c in the 30–35% centrality range,

and then slowly decreases. The maximum shifts to a lower

pTvalue as the events become more peripheral. Whereas

v2{SP}is found to be generally larger than v2{2,|η|>2},

as expected for the narrower range near midpseudorapidity

used for the scalar-product analysis, the situation switches at

higher pTvalues for centralities >30%. This might reﬂect

a larger nonﬂow contribution to the two-particle correlation

results. The pseudorapidity gap of two units used in the

two-particle correlation analysis is less effective in remov-

ing non-ﬂow effects, as compared to the gap of three units

used for the scalar-product analysis. In the most peripheral

events, the v2{2}distribution becomes almost ﬂat for pT>

3.0GeV/c. This may be a consequence of nonﬂow, dijet

correlations dominating the results as the system size becomes

small.

Figure 2shows the v3values. The difference between the

two- and four-particle v3values are larger than found for

the corresponding v2values, exceeding a factor of 2. This

suggests a larger ﬂuctuation component to triangular ﬂow as

compared to elliptic ﬂow. The difference in amplitude would

be qualitatively expected if the v3correlations were dominated

by initial-state ﬂuctuations [18]. For most centralities, the

four-particle distributions have no clear peak value and their

pTdependence is not as prominent as that found for the two-

particle and scalar-product methods. The v3{m>4}values

could not be reliably determined because of their large sta-

tistical uncertainties. The v3{2}(pT) distribution has a similar

shape as found for the v2{2}(pT) distribution, but with smaller

values that approach zero, or even become negative, at higher

pTvalues in the most peripheral centrality ranges.

044902-4

CHARGED-PARTICLE ANGULAR CORRELATIONS … PHYSICAL REVIEW C 100, 044902 (2019)

0.05

0.1

0.15

CMS

Centrality: 0-5%

0.05

0.1

0.15 20-25%

(GeV/c)

02468

0.05

0.1

0.15 40-50%

5-10%

25-30%

(GeV/c)

02468

50-60%

10-15%

30-35%

(GeV/c)

02468

60-70%

15-20%

= 5.44 TeV

sXeXe

35-40%

(GeV/c)

02468

| > 2}ηΔ{2, |

{4}

| < 0.8η, |{SP}

| < 2.4η|

FIG. 2. Triangular-ﬂow coefﬁcients v3based on the different analysis techniques, as functions of transverse momentum and in bins of

centrality, from the 5% most central (top left) to 60–70% centrality (bottom right). The results for the two-particle and multiparticle correlations

correspond to the range |η|<2.4, while the scalar-product results are for |η|<0.8. The bars and the shaded boxes represent statistical and

systematic uncertainties, respectively.

The v4results from the two-particle correlation and scalar-

product methods are presented in Fig. 3.TheQ-cumulant

results are not shown because of statistical limitations. The

shape of the v4(pT) distribution is similar to those for the other

measured harmonics. All three harmonics, with n=2, 3, and

4, are found to have maxima at similar pTvalues, but with

the n=3 and n=4 harmonics having a reduced centrality

dependence as compared to the n=2 harmonic. For all three

harmonics, the scalar-product values are systematically larger

than the two-particle correlation results. While ﬂuctuation

effects are expected to affect both methods in a similar way,

the methods measure ﬂow in different pseudorapidity ranges,

which might account for the observed difference. The similar-

ity of the results suggests there is only a weak pseudorapidity

dependence for all three harmonics.

The spectrum-weighted, single-particle anisotropy coefﬁ-

cients, using the two- and multiparticle correlation methods,

are presented in Fig. 4.Thev2coefﬁcients show a strong

centrality dependence with a maximum value in the 40–

50% centrality bin. The v3and v4coefﬁcients have only a

weak dependence on centrality. Results based on multiparticle

cumulants are below the vn{2}values, as expected for the

inﬂuence of ﬂow ﬂuctuations. The predictions of the IP-

GLASMA+MUSIC+UrQMD model are compared to the ex-

perimental vn{2}results. In this model, initial-state dynamics

are described by impact parameter dependent ﬂowing Glasma

gluon ﬁelds [33]. The subsequent hydrodynamic evolution is

calculated with a MUSIC simulation [34], which is a relativistic

(3 +1)Dmodel that includes shear viscosity (with a shear

viscosity over entropy ratio η/s=0.16) and a temperature-

dependent bulk viscosity over entropy ratio [ζ/s(T)] [35]. The

simulation ﬁnally switches from a ﬂuid-dynamic description

to a transport description using the ultrarelativistic quantum

molecular dynamics (UrQMD) model at the hadronization

hypersurface [36]. The theoretical calculations are in good

agreement with data for the v2and v4values. For the v3

coefﬁcient, the calculation gives slightly larger values than

observed, with the difference increasing as the size of the

nuclear overlap region decreases (i.e., increasing centrality

percentage).

Figure 5shows the ratios v2{6}/v2{4},v2{4}/v2{2}, and

v3{4}/v3{2}. Theoretical predictions from a hydrodynamic

model [37] calculation that uses TRENTo initial conditions

[38] and from the IP-GLASMA+MUSIC+UrQMD model are

compared to the experimental results. The former starts the

hydrodynamic evolution at a time τ=0.6fm/cand has

a shear viscosity to entropy ratio of η/s=0.047. Xenon

is known to be a deformed nucleus with a quadrupole

deformation of 2=0.15 [39]. The TRENTo calculations are

performed assuming both spherical and nominally deformed

xenon nuclei. The v2{4}/v2{2}ratio shows a strong centrality

dependence, with the greatest deviation from unity, with a

value of 0.625, corresponding to 5–10% central events. The

v3{4}/v3{2}and v2{6}/v2{4}ratios show little, if any, central-

ity dependence. The v3{4}/v3{2}has a value close to 0.55 for

all centralities, indicating a strong inﬂuence of ﬂuctuations

on triangular ﬂow [20]. The v2{6}/v2{4}ratio is a few percent

below unity and suggests the existence of higher-order

044902-5

A. M. SIRUNYAN et al. PHYSICAL REVIEW C 100, 044902 (2019)

0.02

0.04

0.06

0.08

0.1

CMS

Centrality: 0-5%

0.02

0.04

0.06

0.08

0.1 20-25%

(GeV/c)

02468

0.02

0.04

0.06

0.08

0.1 40-50%

5-10%

25-30%

(GeV/c)

02468

50-60%

10-15%

30-35%

(GeV/c)

02468

60-70%

15-20%

= 5.44 TeV

sXeXe

35-40%

(GeV/c)

02468

| > 2}ηΔ{2, |

| < 0.8η, |{SP}

| < 2.4η|

FIG. 3. The v4coefﬁcients, based on the different analysis techniques, as functions of transverse momentum and in bins of centrality,

from the 5% most central (top left) to 60–70% centrality (bottom right). The results for the two-particle correlations correspond to the range

|η|<2.4, while the scalar-product results are for |η|<0.8. The bars and the shaded boxes represent statistical and systematic uncertainties,

respectively.

corrections to a near-Gaussian distribution of the event-by-

event ﬂow ﬂuctuations [40]. The IP-GLASMA+MUSIC+

UrQMD and hydrodynamic models give comparable

agreement with data for the ﬂow harmonic ratios. No

signiﬁcant difference is found between the calculations that

assume spherical and deformed Xe nuclear shapes. This

suggests that the ﬂuctuations are not sensitive to the small

deformation associated with the nucleus.

The v2coefﬁcients obtained by the two-particle corre-

lations technique for XeXe collisions at √sNN =5.44 TeV

are compared with corresponding PbPb data at 5.02 TeV

as a function of transverse momentum in various centrality

Centrality (%)

0 1020304050607080

0.02

0.04

0.06

0.08

0.1

0.12 CMS | < 2.4η|

n = 2

Centrality (%)

0 1020304050607080

< 3 GeV/c

0.3 < p

n = 3

Centrality (%)

0 1020304050607080

= 5.44 TeV

sXeXe

n = 4

| > 2}ηΔ{2, |

{4}

{6}

{8}

IP-Glasma+MUSIC+UrQMD

FIG. 4. Centrality dependence of the spectrum-weighted v2,v3,andv4ﬂow harmonics with 0.3<pT<3.0GeV/c. The v2results are

shown for two-, four-, six-, and eight-particle correlations (left panel). The v3results are shown for two- and four-particle correlations

(middle panel), while the v4values are presented for two-particle correlations technique, only. The solid curve in each panel is the

IP-GLASMA+MUSIC+UrQMD prediction for vn{2}. The shaded boxes represent systematic uncertainties.

044902-6

CHARGED-PARTICLE ANGULAR CORRELATIONS … PHYSICAL REVIEW C 100, 044902 (2019)

Centrality (%)

0 10203040506070

Ratio

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.1 CMS

{4}

/v{6}

{2}

/v{4}

IP-Glasma+MUSIC+UrQMD

{

{6}

{

{4}

Gla

Centrality (%)

0 10203040506070

{2}

/v{4}

ENTo

ENTo (Xe deformed)

= 5.44 TeV

sXeXe

| < 2.4η|

< 3.0 GeV/c

0.3 < p

FIG. 5. Centrality dependence of v2{4}/v2{2},v2{6}/v2{4}(left panel), and v3{4}/v3{2}(right panel) ratios. The shaded bands represent the

theoretical predictions based on the IP-GLASMA+MUSIC+UrQMD and the relativistic hydrodynamic model from Ref. [37] considering both

spherical and deformed xenon nuclei, while the widths of the areas show the statistical uncertainties of the model. The TRENTo calculation is

done for the pTrange 0.2<pT<5.0GeV/c.

bins in Fig. 6.Thev2values for the two systems show

similar dependence on pT. However, the maximum value of

the PbPb elliptic ﬂow coefﬁcient is found to be greater than

the corresponding XeXe value except in the 0–5% centrality

bin. Since, for the most central collisions, the participant

ﬂuctuations in the initial-state geometry provide the dominant

contribution to the ﬁnal spacial anisotropy, lower values of v2

in that region are expected [37] for PbPb collisions because

of the larger system size. The v3{2,|η|>2}coefﬁcients for

the two systems are compared in Fig. 7.Thev3harmonic

is entirely generated by initial participant ﬂuctuations, so

slightly larger values are expected in XeXe than in PbPb for

| > 2}ηΔ{2, |

0.05

0.1

0.15

0.2

0.25

CMS

Centrality: 0-5%

| > 2}ηΔ{2, |

0.05

0.1

0.15

0.2

0.25 20-25%

(GeV/c)

02468

| > 2}ηΔ{2, |

0.05

0.1

0.15

0.2

0.25 40-50%

5-10%

25-30%

(GeV/c)

02468

50-60%

10-15%

30-35%

(GeV/c)

02468

60-70%

15-20%

< 3.0 GeV/c

assoc

1.0 < p

35-40%

(GeV/c)

02468

= 5.44 TeV

sXeXe

= 5.02 TeV

sPbPb

|>2}ηΔ{2, |

FIG. 6. Comparison of the v2results measured with two-particle correlations from two different systems, XeXe collisions at √sNN =

5.44 TeV and PbPb collisions at 5.02 TeV, shown as a function of pTin eleven centrality bins. The bars (smaller than the marker size) and the

shaded boxes represent statistical and systematic uncertainties, respectively.

044902-7

A. M. SIRUNYAN et al. PHYSICAL REVIEW C 100, 044902 (2019)

| > 2}ηΔ{2, |

0.05

0.1

0.15

CMS

Centrality: 0-5%

| > 2}ηΔ{2, |

0.05

0.1

0.15 20-25%

(GeV/c)

02468

| > 2}ηΔ{2, |

0.05

0.1

0.15 40-50%

5-10%

25-30%

(GeV/c)

02468

50-60%

10-15%

30-35%

(GeV/c)

02468

60-70%

15-20%

< 3.0 GeV/c

assoc

1.0 < p

35-40%

(GeV/c)

02468

= 5.44 TeV

sXeXe

= 5.02 TeV

sPbPb

|>2}ηΔ{2, |

FIG. 7. Comparison of the v3results measured with two-particle correlations from two different systems, XeXe collisions at √sNN =

5.44 TeV and PbPb collisions at 5.02 TeV, shown as a function of pTin 11 centrality bins. The bars (smaller than the marker size) and the

shaded boxes represent statistical and systematic uncertainties, respectively.

central events (e.g., 0–30% centrality), as observed in the data.

However, the v3harmonic has a larger sensitivity to transport

coefﬁcients (i.e., the shear viscosity) of the created medium,

which tends to suppress the azimuthal anisotropy, especially

for systems with a small size. This might explain the trend

of v3where the system with the larger value is reversed in

the 30–70% centrality range, with the larger PbPb system

showing slightly higher v3values for more peripheral events.

The v4{2,|η|>2}coefﬁcients in PbPb and XeXe collisions

are shown in Fig. 8. Higher v4values are found for PbPb

collisions, as compared to the corresponding XeXe collision

results, except for the transverse momentum interval pT<

3.0GeV/c in the 5% most central events. The ordering of the

measured harmonics between the two systems is consistent

with participant ﬂuctuations having a dominant role in central

collisions, and viscosity effects becoming more important for

mid-central and peripheral collisions.

Since ideal hydrodynamics is scale invariant, the XeXe and

PbPb results should have similar behavior [37]. For the same

percentage centrality range, the interaction regions of the two

colliding systems will have similar average shapes, but will

have different size. For example, in the 30–40% centrality

class, the number of participating nucleons is about 1.6 times

higher for the PbPb collisions. However, initial-state ﬂuctu-

ations and viscosity corrections can cause scale invariance

breaking. Fluctuations of the initial state are proportional to

A−1/2, where Ais the atomic mass, and, therefore, one can

expect a larger ﬂuctuation component for XeXe collisions

than for PbPb collisions [41]. However, the inﬂuence of the

localized ﬂuctuations will decrease with increasing viscosity.

The viscosity is thought to be proportional to A−1/3[42] and

is therefore also expected to be larger for XeXe collisions.

Although the hydrodynamic model simulations do not suggest

a large effect on the vn{4}/vn{2}and v2{6}/v2{4}ratios based

on the Xe deformation, this deformation can inﬂuence the

ratio of the XeXe and PbPb results. The quadrupole defor-

mation of the colliding nuclei is expected to have the greatest

inﬂuence for the XeXe v2values corresponding to the most

central collisions [37].

Figure 9shows the pTdependent ratios of XeXe and

PbPb harmonic coefﬁcients for different centrality ranges.

The ratios reach a maximum value between 1 and 2 GeV/c,

within the current uncertainties, and then decrease up to pT∼

6GeV/c, at which point they start to increase again. The

increasing trend above 6 GeV/c, which is most pronounced

for the v2coefﬁcient, might be a consequence of back-to-back

dijet correlations that cannot be fully eliminated with the

|η|>2 requirement. This nonﬂow behavior is increasingly

signiﬁcant as the system size becomes smaller, with corre-

spondingly smaller particle multiplicities.

Figure 10 compares the spectrum-weighted v2,v3, and v4

values with 0.3<pT<3.0GeV/c for the XeXe and PbPb

systems. The largest difference between the two systems is

found for the v2coefﬁcients corresponding to the most central

events, where the XeXe results are larger by a factor of about

1.3. For centralities above 10%, the PbPb results become

higher and the ratio has only a weak centrality dependence.

For the v3and v4coefﬁcients, the ratio vn[XeXe]/vn[PbPb]

044902-8

CHARGED-PARTICLE ANGULAR CORRELATIONS … PHYSICAL REVIEW C 100, 044902 (2019)

|>2}ηΔ{2, |

0.02

0.04

0.06

0.08

0.1

CMS

Centrality: 0-5%

|>2}ηΔ{2, |

0.02

0.04

0.06

0.08

0.1 20-25%

(GeV/c)

02468

|>2}ηΔ{2, |

0.02

0.04

0.06

0.08

0.1 40-50%

5-10%

25-30%

(GeV/c)

02468

50-60%

10-15%

30-35%

(GeV/c)

02468

60-70%

15-20%

< 3.0 GeV/c

assoc

1.0 < p

35-40%

(GeV/c)

02468

= 5.44 TeV

sXeXe

= 5.02 TeV

sPbPb

|>2}ηΔ{2, |

FIG. 8. Comparison of the v4results measured with two-particle correlations from two different systems, XeXe collisions at √sNN =

5.44 TeV and PbPb collisions at 5.02 TeV, shown as a function of pTin 11 centrality bins. The bars and the shaded boxes represent statistical

and systematic uncertainties, respectively.

[PbPb]

[XeXe]/v

0.6

0.8

1.2

1.4

CMS

Centrality: 0-5%

[PbPb]

[XeXe]/v

0.6

0.8

1.2

1.4 20-25%

(GeV/c)

02468

[PbPb]

[XeXe]/v

0.6

0.8

1.2

1.4 40-50%

5-10%

25-30%

(GeV/c)

02468

50-60%

10-15%

30-35%

(GeV/c)

02468

60-70%

15-20%

< 3.0 GeV/c

assoc

1.0 < p

35-40%

(GeV/c)

02468

n = 2

n = 3

n = 4

=5.02 TeV

s[PbPb]

=5.44 TeV

s[XeXe]

FIG. 9. Ratios of the v2,v3,andv4harmonic coefﬁcients from two-particle correlations in XeXe and PbPb collisions as functions of pTin

11 centrality bins. The bars and the shaded boxes represent statistical and systematic uncertainties, respectively.

044902-9

A. M. SIRUNYAN et al. PHYSICAL REVIEW C 100, 044902 (2019)

| > 2}ηΔ{2, |

0.02

0.04

0.06

0.08

0.1

0.12 n = 2

CMS

Centrality (%)

0 1020304050607080

[PbPb]

[XeXe]/v

0.8

0.9

1.1

1.2

1.3 Data

ENTo

ENTo (Xe deformed)

n = 3

Centrality (%)

0 1020304050607080

n = 4

= 5.44 TeV

sXeXe

= 5.02 TeV

sPbPb

< 3 GeV/c

0.3 < p

Centrality (%)

0 1020304050607080

FIG. 10. Centrality dependence of the spectrum-weighted v2,v3,andv4harmonic coefﬁcients from two-particle correlations method for

0.3<pT<3.0GeV/c for XeXe collisions at √sNN =5.44 TeV and PbPb collisions at 5.02 TeV. The lower panels show the ratio of the results

for the two systems. The bars and the shaded boxes represent statistical and systematic uncertainties, respectively. Theoretical predictions from

Ref. [37] are compared to the data (shaded bands). The model calculation is done for the pTrange 0.2<pT<5.0GeV/c.

decreases with centrality with an almost constant slope. The

relativistic hydrodynamic model calculations of Ref. [37]are

also shown in Fig. 10. Compared to calculations assuming a

spherical Xe shape, including the xenon nuclear deformation

in hydrodynamic models has little effect on the predicted ﬂow

characteristics over the centrality range 10–70%, as expected.

For the most central 0–10% range, the v2[XeXe]/v2[PbPb]

model ratio shows a greater sensitivity to the xenon nuclear

deformation, with the calculation including deformation in

better agreement with experiment. For all measured harmon-

ics, the model values lie below the experimental results, with

the greatest difference found for the v4coefﬁcients.

VII. SUMMARY

In this paper, the v2,v3, and v4azimuthal ﬂow harmonics

are shown for xenon-xenon (XeXe) collisions at a center-of-

mass energy per nucleon pair of √sNN =5.44 TeV based

on data obtained with the CMS detector. Three analysis

techniques with different sensitivities to ﬂow ﬂuctuations, in-

cluding two-particle correlations, the scalar-product method,

and the multiparticle cumulant method, are used to explore

the event-by-event ﬂuctuations. The harmonic coefﬁcients are

compared to those found with lead-lead (PbPb) collisions at

√sNN =5.02 TeV to explore the effect of the system size.

The magnitude of the v2coefﬁcients for XeXe collisions

are larger than those found in PbPb collisions for the most

central collisions. This is attributed to a larger ﬂuctuation

component in the lighter colliding system. In more peripheral

events, the PbPb vncoefﬁcients are consistently larger than

those found for XeXe collisions. This behavior is qualitatively

consistent with expectations from hydrodynamic models. A

clear ordering v2{2}>v2{4}≈v2{6}≈v2{8}is observed for

XeXe collisions, with v2{6}and v2{4}values differing by

2–3%. The v3{4}/v3{2}ratio is found to be signiﬁcantly

smaller than the v2{4}/v2{2}ratio, suggesting a dominant

ﬂuctuation component for the v3harmonic. Hydrodynamic

models that consider the xenon nuclear deformation are able

to better describe the v2[XeXe]/v2[PbPb] ratio in central

collisions than those assuming a spherical Xe shape, al-

though the deformation appears to have little effect on the

ﬂuctuation-sensitive ratio of the cumulant orders. These mea-

surements provide new tests of hydrodynamic models and

help to constrain hydrodynamic descriptions of the nuclear

collisions.

ACKNOWLEDGMENTS

We congratulate our colleagues in the CERN accelerator

departments for the excellent performance of the LHC and

thank the technical and administrative staffs at CERN and

at other CMS institutes for their contributions to the success

of the CMS effort. In addition, we gratefully acknowledge

the computing centers and personnel of the Worldwide

LHC Computing Grid for delivering so effectively the

computing infrastructure essential to our analyses. Finally,

we acknowledge the enduring support for the construction

and operation of the LHC and the CMS detector provided

by the following funding agencies: BMBWF and FWF

(Austria); FNRS and FWO (Belgium); CNPq, CAPES,

FAPERJ, FAPERGS, and FAPESP (Brazil); MES (Bulgaria);

CERN; CAS, MoST, and NSFC (China); COLCIENCIAS

(Colombia); MSES and CSF (Croatia); RPF (Cyprus);

SENESCYT (Ecuador); MoER, ERC IUT, and ERDF

(Estonia); Academy of Finland, MEC, and HIP (Finland);

CEA and CNRS/IN2P3 (France); BMBF, DFG, and HGF

044902-10

CHARGED-PARTICLE ANGULAR CORRELATIONS … PHYSICAL REVIEW C 100, 044902 (2019)

(Germany); GSRT (Greece); NKFIA (Hungary); DAE

and DST (India); IPM (Iran); SFI (Ireland); INFN (Italy);

MSIP and NRF (Republic of Korea); MES (Latvia); LAS

(Lithuania); MOE and UM (Malaysia); BUAP, CINVESTAV,

CONACYT, LNS, SEP, and UASLP-FAI (Mexico); MOS

(Montenegro); MBIE (New Zealand); PAEC (Pakistan);

MSHE and NSC (Poland); FCT (Portugal); JINR (Dubna);

MON, RosAtom, RAS, RFBR, and NRC KI (Russia);

MESTD (Serbia); SEIDI, CPAN, PCTI, and FEDER

(Spain); MOSTR (Sri Lanka); Swiss Funding Agencies

(Switzerland); MST (Taipei); ThEPCenter, IPST, STAR,

and NSTDA (Thailand); TUBITAK and TAEK (Turkey);

NASU and SFFR (Ukraine); STFC (United Kingdom);

DOE and NSF (USA). Individuals have received support

from the Marie-Curie program and the European Research

Council and Horizon 2020 Grant, Contracts No. 675440 and

No. 765710 (European Union); the Leventis Foundation;

the A.P. Sloan Foundation; the Alexander von Humboldt

Foundation; the Belgian Federal Science Policy Ofﬁce; the

Fonds pour la Formation à la Recherche dans l’Industrie et

dans l’Agriculture (FRIA-Belgium); the Agentschap voor

Innovatie door Wetenschap en Technologie (IWT-Belgium);

the F.R.S.-FNRS and FWO (Belgium) under the “Excellence

of Science – EOS” – be.h Project No. 30820817; the

Beijing Municipal Science & Technology Commission,

No. Z181100004218003; the Ministry of Education, Youth

and Sports (MEYS) of the Czech Republic; the Lendület

(“Momentum”) Program and the János Bolyai Research

Scholarship of the Hungarian Academy of Sciences, the

New National Excellence Program ÚNKP, the NKFIA

Research Grants No. 123842, No. 123959, No. 124845,

No. 124850, and No. 125105 (Hungary); the Council of

Science and Industrial Research, India; the HOMING PLUS

program of the Foundation for Polish Science, coﬁnanced

by European Union, Regional Development Fund, the

Mobility Plus program of the Ministry of Science and

Higher Education, the National Science Center (Poland),

Contracts No. Harmonia 2014/14/M/ST2/00428, No.

Opus 2014/13/B/ST2/02543, No. 2014/15/B/ST2/03998,

and No. 2015/19/B/ST2/02861, No. Sonata-bis

2012/07/E/ST2/01406; the National Priorities Research

Program by Qatar National Research Fund; the Programa

Estatal de Fomento de la Investigación Cientíﬁca y Técnica

de Excelencia María de Maeztu, Grant No. MDM-2015-0509

and the Programa Severo Ochoa del Principado de Asturias;

the Thalis and Aristeia programs coﬁnanced by EU-ESF

and the Greek NSRF; the Rachadapisek Sompot Fund for

Postdoctoral Fellowship, Chulalongkorn University and

the Chulalongkorn Academic into its 2nd Century Project

Advancement Project (Thailand); the Welch Foundation,

Contract No. C-1845; and the Weston Havens Foundation

(USA).

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B. Pavlov,13 P. Petkov,13 W. Fang,14 ,fX. Gao,14,fL. Yuan,14 M. Ahmad,15 J. G. Bian,15 G. M. Chen,15 H. S. Chen,15 M. Chen,15
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A. M. SIRUNYAN et al. PHYSICAL REVIEW C 100, 044902 (2019)
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P. Azzi,72a,72b,72c N. Bacchetta,72a,72b,72c D. Bisello,72a,72b,72c A. Boletti,72a,72b,72c A. Bragagnolo,72a,72b,72c R. Carlin,72a,72b,72c
P. Checchia,72a,72b,72c M. Dall’Osso,72a,72b,72c P. De Castro Manzano,72a,72b,72c T. Dorigo,72a,72b,72c U. Dosselli,72a,72b,72c
F. Gasparini,72a,72b,72c U. Gasparini,72a,72b,72c A. Gozzelino,72a,72b,72c S. Y. Hoh,72a,72b,72c S. Lacaprara,72a,72b,72c
P. Lujan,72a,72b,72c M. Margoni,72a,72b,72c A. T. Meneguzzo,72a,72b,72c J. Pazzini,72a,72b,72c P. Ronchese,72a,72b,72c
R. Rossin,72a,72b,72c F. Simonetto,72a,72b,72c A. Tiko,72a,72b,72c E. Torassa,72a,72b,72c M. Zanetti,72a,72b,72c P. Zotto,72a,72b,72c
G. Zumerle,72a,72b,72c A. Braghieri,73a,73b A. Magnani,73a,73b P. Montagna,73a,73b S. P. Ratti,73a,73b V. R e ,73a,73b
M. Ressegotti,73a,73b C. Riccardi,73a,73b P. Salvini,73a,73b I. Vai,73a,73b P. Vitulo,73a,73b M. Biasini,74a,74b G. M. Bilei,74a,74b
C. Cecchi,74a,74b D. Ciangottini,74a,74b L. Fanò,74a,74b P. Lariccia,74a,74b R. Leonardi,74a,74b E. Manoni,74a,74b G. Mantovani,74a,74b
V. Mariani,74a,74b M. Menichelli,74a,74b A. Rossi,74a,74b A. Santocchia,74a,74b D. Spiga,74a,74b K. Androsov,75a,75b,75c
P. Azzurri,75a,75b,75c G. Bagliesi,75a,75b,75c L. Bianchini,75a,75b,75c T. Boccali,75a,75b,75c L. Borrello,75a,75b,75c R. Castaldi,75a,75b,75c
M. A. Ciocci,75a,75b,75c R. Dell’Orso,75a,75b,75c G. Fedi,75a,75b,75c F. Fiori,75a,75b,75c L. Giannini,75a,75b,75c A. Giassi,75a,75b,75c
M. T. Grippo,75a,75b,75c F. Ligabue,75a,75b,75c E. Manca,75a,75b,75c G. Mandorli,75a,75b,75c A. Messineo,75a,75b,75c F. Palla,75a,75b,75c
A. Rizzi,75a,75b,75c P. Spagnolo,75a,75b,75c R. Tenchini,75a,75b,75c G. Tonelli,75a,75b,75c A. Venturi,75a,75b,75c P. G. Verdini,75a,75b,75c
L. Barone,76a,76b F. Cavallari,76a,76b M. Cipriani,76a,76b D. Del Re,76a,76b E. Di Marco,76a,76b M. Diemoz,76a,76b S. Gelli,76a,76b
E. Longo,76a,76b B. Marzocchi,76a,76b P. Meridiani,76a,76b G. Organtini,76a,76b F. Pandolﬁ,76a,76b R. Paramatti,76a,76b
F. Preiato,76a,76b S. Rahatlou,76a,76b C. Rovelli,76a,76b F. Santanastasio,76a,76b N. Amapane,77a,77b,77c R. Arcidiacono,77a,77b,77c
S. Argiro,77a,77b,77c M. Arneodo,77a,77b,77c N. Bartosik,77a,77b,77c R. Bellan,77a,77b,77c C. Biino,77a,77b,77c N. Cartiglia,77a,77b,77c
F. Cenna,77a,77b,77c S. Cometti,77a,77b,77c M. Costa,77a,77b,77c R. Covarelli,77a,77b,77c N. Demaria,77a,77b,77c B. Kiani,77a,77b,77c
C. Mariotti,77a,77b,77c S. Maselli,77a,77b,77c E. Migliore,77a,77b,77c V. Monaco,77a,77b,77c E. Monteil,77a,77b,77c M. Monteno,77a,77b,77c
M. M. Obertino,77a,77b,77c L. Pacher,77a,77b,77c N. Pastrone,77a,77b,77c M. Pelliccioni,77a,77b,77c G. L. Pinna Angioni,77a,77b,77c
A. Romero,77a,77b,77c M. Ruspa,77a,77b,77c R. Sacchi,77a,77b,77c K. Shchelina,77a,77b,77c V. Sola,77a,77b,77c A. Solano,77a,77b,77c
D. Soldi,77a,77b,77c A. Staiano,77a,77b,77c S. Belforte,78a,78b V. Candelise,78a,78b M. Casarsa,78a,78b F. Cossutti,78a,78b A. Da
Rold,78a,78b G. Della Ricca,78a,78b F. Vazzoler,78a,78b A. Zanetti,78a,78b D. H. Kim,79 G. N. Kim,79 M. S. Kim,79 J. Lee,79
S. Lee,79 S. W. Lee,79 C. S. Moon,79 Y. D. Oh,79 S. I. Pak,79 S. Sekmen,79 D. C. Son,79 Y. C. Yang,79 H. Kim,80 D. H. Moon,80
G. Oh,80 J. Goh,81,ae T. J. Kim,81 S. Cho,82 S. Choi,82 Y. Go ,82 D. Gyun,82 S. Ha,82 B. Hong,82 Y. J o, 82 K. Lee,82 K. S. Lee,82
S. Lee,82 J. Lim,82 S. K. Park,82 Y. Roh,82 H. S. Kim,83 J. Almond,84 J. Kim,84 J. S. Kim,84 H. Lee,84 K. Lee,84 K. Nam,84
S. B. Oh,84 B. C. Radburn-Smith,84 S. h. Seo,84 U. K. Yang,84 H. D. Yoo,84 G. B. Yu,84 D. Jeon,85 H. Kim,85 J. H. Kim,85
J. S. H. Lee,85 I. C. Park,85 Y. Choi,86 C. Hwang,86 J. Lee,86 I. Yu,86 V. Dudenas,87 A. Juodagalvis,87 J. Vaitkus,87 I. Ahmed,88
Z. A. Ibrahim,88 M. A. B. Md Ali,88,af F. Mohamad Idris,88,ag W. A. T. Wan Abdullah,88 M. N. Yusli,88 Z. Zolkapli,88
J. F. Benitez,89 A. Castaneda Hernandez,89 J. A. Murillo Quijada,89 H. Castilla-Valdez,90 E. De La Cruz-Burelo,90
044902-14

CHARGED-PARTICLE ANGULAR CORRELATIONS … PHYSICAL REVIEW C 100, 044902 (2019)
M. C. Duran-Osuna,90 I. Heredia-De La Cruz,90,ah R. Lopez-Fernandez,90 J. Mejia Guisao,90 R. I. Rabadan-Trejo,90
M. Ramirez-Garcia,90 G. Ramirez-Sanchez,90 R Reyes-Almanza,90 A. Sanchez-Hernandez,90 S. Carrillo Moreno,91
C. Oropeza Barrera,91 F. Vazquez Valencia,91 J. Eysermans,92 I. Pedraza,92 H. A. Salazar Ibarguen,92 C. Uribe Estrada,92
A. Morelos Pineda,93 D. Krofcheck,94 S. Bheesette,95 P. H. Butler,95 A. Ahmad,96 M. Ahmad,96 M. I. Asghar,96 Q. Hassan,96
H. R. Hoorani,96 A. Saddique,96 M. A. Shah,96 M. Shoaib,96 M. Waqas,96 H. Bialkowska,97 M. Bluj,97 B. Boimska,97
T. Frueboes,97 M. Górski,97 M. Kazana,97 M. Szleper,97 P. Traczyk,97 P. Za l ews ki , 97 K. Bunkowski,98 A. Byszuk,98,ai
K. Doroba,98 A. Kalinowski,98 M. Konecki,98 J. Krolikowski,98 M. Misiura,98 M. Olszewski,98 A. Pyskir,98 M. Walczak,98
M. Araujo,99 P. Bargassa,99 C. Beirão Da Cruz E Silva,99 A. Di Francesco,99 P. Faccioli,99 B. Galinhas,99 M. Gallinaro,99
J. Hollar,99 N. Leonardo,99 M. V. Nemallapudi,99 J. Seixas,99 G. Strong,99 O. Toldaiev,99 D. Vadruccio,99 J. Varela,99
S. Afanasiev,100 P. Bunin,100 M. Gavrilenko,100 I. Golutvin,100 I. Gorbunov,100 A. Kamenev,100 V. Karjavine,100 A. Lanev,100
A. Malakhov,100 V. Matveev,100,aj P. Moisenz,100 V. Palichik,100 V. Perelygin,100 S. Shmatov,100 S. Shulha,100 N. Skatchkov,100
V. Smirnov,100 N. Voytishin,100 A. Zarubin,100 V. Golovtsov,101 Y. Ivanov,101 V. Kim,101,ak E. Kuznetsova,101,al
P. Levchenko,101 V. Mu r z i n, 101 V. Oreshkin,101 I. Smirnov,101 D. Sosnov,101 V. Sulimov,101 L. Uvarov,101 S. Vavilov,101
A. Vorobyev,101 Yu. Andreev,102 A. Dermenev,102 S. Gninenko,102 N. Golubev,102 A. Karneyeu,102 M. Kirsanov,102
N. Krasnikov,102 A. Pashenkov,102 D. Tlisov,102 A. Toropin,102 V. Epshteyn,103 V. Gavrilov,103 N. Lychkovskaya,103
V. Popov,103 I. Pozdnyakov,103 G. Safronov,103 A. Spiridonov,103 A. Stepennov,103 V. Stolin,103 M. Toms,103 E. Vlasov,103
A. Zhokin,103 T. Au s h ev,104 R. Chistov,105,am M. Danilov,105,am P. Parygin,105 D. Philippov,105 S. Polikarpov,105,am
E. Tarkovskii,105 V. Andreev,106 M. Azarkin,106 I. Dremin,106,an M. Kirakosyan,106 S. V. Rusakov,106 A. Terkulov,106
A. Baskakov,107 A. Belyaev,107 E. Boos,107 A. Ershov,107 A. Gribushin,107 A. Kaminskiy,107 ,ao O. Kodolova,107
V. Korotkikh,107 I. Lokhtin,107 I. Miagkov,107 S. Obraztsov,107 S. Petrushanko,107 V. Savrin,107 A. Snigirev,107 I. Vardanyan,107
A. Barnyakov,108,ap V. Blinov,108,ap T. Dimova,108,ap L. Kardapoltsev,108,ap Y. Skovpen,108,ap I. Azhgirey,109 I. Bayshev,109
S. Bitioukov,109 D. Elumakhov,109 A. Godizov,109 V. Kachanov,109 A. Kalinin,109 D. Konstantinov,109 P. Mandrik,109
V. Petrov,109 R. Ryutin,109 S. Slabospitskii,109 A. Sobol,109 S. Troshin,109 N. Tyurin,109 A. Uzunian,109 A. Volkov,109
A. Babaev,110 S. Baidali,110 V. Okhotnikov,110 P. Adzic,111,aq P. C ir k ovi c,111 D. Devetak,111 M. Dordevic,111 J. Milosevic,111
M. Stojanovic,111 J. Alcaraz Maestre,112 A. Álvarez Fernández,112 I. Bachiller,112 M. Barrio Luna,112
J. A. Brochero Cifuentes,112 M. Cerrada,112 N. Colino,112 B. De La Cruz,112 A. Delgado Peris,112 C. Fernandez Bedoya,112
J. P. Fernández Ramos,112 J. Flix,112 M. C. Fouz,112 O. Gonzalez Lopez,112 S. Goy Lopez,112 J. M. Hernandez,112 M. I. Josa,112
D. Moran,112 A. Pérez-Calero Yzquierdo,112 J. Puerta Pelayo,112 I. Redondo,112 L. Romero,112 M. S. Soares,112 A. Triossi,112
C. Albajar,113 J. F. de Trocóniz,113 J. Cuevas,114 C. Erice,114 J. Fernandez Menendez,114 S. Folgueras,114
I. Gonzalez Caballero,114 J. R. González Fernández,114 E. Palencia Cortezon,114 V. Rodríguez Bouza,114 S. Sanchez Cruz,114
P. Vischia,114 J. M. Vizan Garcia,114 I. J. Cabrillo,115 A. Calderon,115 B. Chazin Quero,115 J. Duarte Campderros,115
M. Fernandez,115 P. J. Fernández Manteca,115 A. García Alonso,115 J. Garcia-Ferrero,115 G. Gomez,115 A. Lopez Virto,115
J. Marco,115 C. Martinez Rivero,115 P. Martinez Ruiz del Arbol,115 F. Matorras,115 J. Piedra Gomez,115 C. Prieels,115
T. Rodrigo,115 A. Ruiz-Jimeno,115 L. Scodellaro,115 N. Trevisani,115 I. Vila,115 R. Vilar Cortabitarte,115 N. Wickramage,116
D. Abbaneo,117 B. Akgun,117 E. Auffray,117 G. Auzinger,117 P. Baillon,117 A. H. Ball,117 D. Barney,117 J. Bendavid,117
M. Bianco,117 A. Bocci,117 C. Botta,117 E. Brondolin,117 T. Camporesi,117 M. Cepeda,117 G. Cerminara,117 E. Chapon,117
Y. Chen,117 G. Cucciati,117 D. d’Enterria,117 A. Dabrowski,117 N. Daci,117 V. Daponte,117 A. David,117 A. De Roeck,117
N. Deelen,117 M. Dobson,117 M. Dünser,117 N. Dupont,117 A. Elliott-Peisert,117 P. Everaerts,117 F. Fallavollita,117,ar
D. Fasanella,117 G. Franzoni,117 J. Fulcher,117 W. Funk,117 D. Gigi,117 A. Gilbert,117 K. Gill,117 F. Glege,117 M. Guilbaud,117
D. Gulhan,117 J. Hegeman,117 C. Heidegger,117 V. Innocente,117 A. Jafari,117 P. Janot,117 O. Karacheban,117,sJ. Kieseler,117
A. Kornmayer,117 M. Krammer,117,bC. Lange,117 P. Lecoq,117 C. Lourenço,117 L. Malgeri,117 M. Mannelli,117 F. Meijers,117
J. A. Merlin,117 S. Mersi,117 E. Meschi,117 P. Milenovic,117,as F. Moortgat,117 M. Mulders,117 J. Ngadiuba,117 S. Nourbakhsh,117
S. Orfanelli,117 L. Orsini,117 F. Pantaleo,117,pL. Pape,117 E. Perez,117 M. Peruzzi,117 A. Petrilli,117 G. Petrucciani,117
A. Pfeiffer,117 M. Pierini,117 F. M. Pitters,117 D. Rabady,117 A. Racz,117 T. Reis,117 G. Rolandi,117,at M. Rovere,117
H. Sakulin,117 C. Schäfer,117 C. Schwick,117 M. Seidel,117 M. Selvaggi,117 A. Sharma,117 P. Silva,117 P. Sphicas,117,au
A. Stakia,117 J. Steggemann,117 M. Tosi,117 D. Treille,117 A. Tsirou,117 V. Veckalns,117 ,av M. Verzetti,117 W. D. Zeuner,117
L. Caminada,118,aw K. Deiters,118 W. Erdmann,118 R. Horisberger,118 Q. Ingram,118 H. C. Kaestli,118 D. Kotlinski,118
U. Langenegger,118 T. Rohe,118 S. A. Wiederkehr,118 M. Backhaus,119 L. Bäni,119 P. Berger,119 N. Chernyavskaya,119
G. Dissertori,119 M. Dittmar,119 M. Donegà,119 C. Dorfer,119 T. A. Gómez Espinosa,119 C. Grab,119 D. Hits,119 T. Klijnsma,119
W. Lustermann,119 R. A. Manzoni,119 M. Marionneau,119 M. T. Meinhard,119 F. Micheli,119 P. Musella,119 F. Nessi-Tedaldi,119
J. Pata,119 F. Pauss,119 G. Perrin,119 L. Perrozzi,119 S. Pigazzini,119 M. Quittnat,119 C. Reissel,119 D. Ruini,119
D. A. Sanz Becerra,119 M. Schönenberger,119 L. Shchutska,119 V. R. Tavolaro,119 K. Theoﬁlatos,119
M. L. Vesterbacka Olsson,119 R. Wallny,119 D. H. Zhu,119 T. K. Aarrestad,120 C. Amsler,120,ax D. Brzhechko,120
M. F. Canelli,120 A. De Cosa,120 R. Del Burgo,120 S. Donato,120 C. Galloni,120 T. Hreus,120 B. Kilminster,120 S. Leontsinis,120
I. Neutelings,120 G. Rauco,120 P. Robmann,120 D. Salerno,120 K. Schweiger,120 C. Seitz,120 Y. Takahashi,120 A. Zucchetta,120
Y. H. Chang,121 K. y. Cheng,121 T. H. Doan,121 R. Khurana,121 C. M. Kuo,121 W. Lin, 121 A. Pozdnyakov,121 S. S. Yu,121
P. Chang,122 Y. Chao,122 K. F. Chen,122 P. H. Chen,122 W.-S. Hou,122 Arun Kumar,122 Y. F. L i u ,122 R.-S. Lu,122 E. Paganis,122
A. Psallidas,122 A. Steen,122 B. Asavapibhop,123 N. Srimanobhas,123 N. Suwonjandee,123 A. Bat,124 F. Boran,124
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A. M. SIRUNYAN et al. PHYSICAL REVIEW C 100, 044902 (2019)
S. Damarseckin,124 Z. S. Demiroglu,124 F. Dolek,124 C. Dozen,124 I. Dumanoglu,124 E. Eskut,124 S. Girgis,124 G. Gokbulut,124
Y. Gu l e r ,124 E. Gurpinar,124 I. Hos,124,ay C. Isik,124 E. E. Kangal,124,az O. Kara,124 A. Kayis Topaksu,124 U. Kiminsu,124
M. Oglakci,124 G. Onengut,124 K. Ozdemir,124,ba A. Polatoz,124 D. Sunar Cerci,124 ,bb B. Tali,124,bb U. G. Tok,124
S. Turkcapar,124 I. S. Zorbakir,124 C. Zorbilmez,124 B. Isildak,125,bc G. Karapinar,125,bd M. Yalvac,125 M. Zeyrek,125
I. O. Atakisi,126 E. Gülmez,126 M. Kaya,126,be O. Kaya,126 ,bf S. Ozkorucuklu,126,bg S. Tekten,126 E. A. Yetkin,126 ,bh
M. N. Agaras,127 A. Cakir,127 K. Cankocak,127 Y. Komurcu,127 S. Sen,127,bi B. Grynyov,128 L. Levchuk,129 F. Ball,130
L. Beck,130 J. J. Brooke,130 D. Burns,130 E. Clement,130 D. Cussans,130 O. Davignon,130 H. Flacher,130 J. Goldstein,130
G. P. Heath,130 H. F. Heath,130 L. Kreczko,130 D. M. Newbold,130 ,bj S. Paramesvaran,130 B. Penning,130 T. Sakuma,130
D. Smith,130 V. J. Smith,130 J. Taylor,130 A. Titterton,130 A. Belyaev,131,bk C. Brew,131 R. M. Brown,131 D. Cieri,131
D. J. A. Cockerill,131 J. A. Coughlan,131 K. Harder,131 S. Harper,131 J. Linacre,131 E. Olaiya,131 D. Petyt,131
C. H. Shepherd-Themistocleous,131 A. Thea,131 I. R. Tomalin,131 T. Williams,131 W. J. Womersley,131 R. Bainbridge,132
P. Bloch,132 J. Borg,132 S. Breeze,132 O. Buchmuller,132 A. Bundock,132 D. Colling,132 P. Dauncey,132 G. Davies,132
M. Della Negra,132 R. Di Maria,132 Y. Haddad,132 G. Hall,132 G. Iles,132 T. James,132 M. Komm,132 C. Laner,132 L. Lyons,132
A.-M. Magnan,132 S. Malik,132 A. Martelli,132 J. Nash,132,bl A. Nikitenko,132,hV. Palladino,132 M. Pesaresi,132
D. M. Raymond,132 A. Richards,132 A. Rose,132 E. Scott,132 C. Seez,132 A. Shtipliyski,132 G. Singh,132 M. Stoye,132
T. Strebler,132 S. Summers,132 A. Tapper,132 K. Uchida,132 T. Virdee,132,pN. Wardle,132 D. Winterbottom,132 J. Wright,132
S. C. Zenz,132 J. E. Cole,133 P. R. Hobson,133 A. Khan,133 P. Kyberd,133 C. K. Mackay,133 A. Morton,133 I. D. Reid,133
L. Teodorescu,133 S. Zahid,133 K. Call,134 J. Dittmann,134 K. Hatakeyama,134 H. Liu,134 C. Madrid,134 B. Mcmaster,134
N. Pastika,134 C. Smith,134 R. Bartek,135 A. Dominguez,135 A. Buccilli,136 S. I. Cooper,136 C. Henderson,136 P. Rum er i o, 136
C. West,136 D. Arcaro,137 T. B ose,137 D. Gastler,137 D. Pinna,137 D. Rankin,137 C. Richardson,137 J. Rohlf,137 L. Sulak,137
D. Zou,137 G. Benelli,138 X. Coubez,138 D. Cutts,138 M. Hadley,138 J. Hakala,138 U. Heintz,138 J. M. Hogan,138,bm
K. H. M. Kwok,138 E. Laird,138 G. Landsberg,138 J. Lee,138 Z. Mao,138 M. Narain,138 S. Sagir,138,bn R. Syarif,138 E. Usai,138
D. Yu,138 R. Band,139 C. Brainerd,139 R. Breedon,139 D. Burns,139 M. Calderon De La Barca Sanchez,139 M. Chertok,139
J. Conway,139 R. Conway,139 P. T. Cox,139 R. Erbacher,139 C. Flores,139 G. Funk,139 W. Ko,139 O. Kukral,139 R. Lander,139
M. Mulhearn,139 D. Pellett,139 J. Pilot,139 S. Shalhout,139 M. Shi,139 D. Stolp,139 D. Taylor,139 K. Tos,139 M. Tripathi,139
Z. Wang,139 F. Zhang,139 M. Bachtis,140 C. Bravo,140 R. Cousins,140 A. Dasgupta,140 A. Florent,140 J. Hauser,140
M. Ignatenko,140 N. Mccoll,140 S. Regnard,140 D. Saltzberg,140 C. Schnaible,140 V. Val ue v , 140 E. Bouvier,141 K. Burt,141
R. Clare,141 J. W. Gary,141 S. M. A. Ghiasi Shirazi,141 G. Hanson,141 G. Karapostoli,141 E. Kennedy,141 F. Lacroix,141
O. R. Long,141 M. Olmedo Negrete,141 M. I. Paneva,141 W. S i,141 L. Wang,141 H. Wei,141 S. Wimpenny,141 B. R. Yates,141
J. G. Branson,142 P. Chang,142 S. Cittolin,142 M. Derdzinski,142 R. Gerosa,142 D. Gilbert,142 B. Hashemi,142 A. Holzner,142
D. Klein,142 G. Kole,142 V. Krutelyov,142 J. Letts,142 M. Masciovecchio,142 D. Olivito,142 S. Padhi,142 M. Pieri,142 M. Sani,142
V. Sharma,142 S. Simon,142 M. Tadel,142 A. Vartak,142 S. Wasserbaech,142,bo J. Wood,142 F. Würthwein,142 A. Yagil,142
G. Zevi Della Porta,142 N. Amin,143 R. Bhandari,143 J. Bradmiller-Feld,143 C. Campagnari,143 M. Citron,143 A. Dishaw,143
V. Dutta,143 M. Franco Sevilla,143 L. Gouskos,143 R. Heller,143 J. Incandela,143 A. Ovcharova,143 H. Qu,143 J. Richman,143
D. Stuart,143 I. Suarez,143 S. Wang,143 J. Yoo,143 D. Anderson,144 A. Bornheim,144 J. M. Lawhorn,144 H. B. Newman,144
T. Q. Nguyen,144 M. Spiropulu,144 J. R. Vlimant,144 R. Wilkinson,144 S. Xie,144 Z. Zhang,144 R. Y. Zhu,144 M. B. Andrews,145
T. Ferguson,145 T. Mudholkar,145 M. Paulini,145 M. Sun,145 I. Vorobiev,145 M. Weinberg,145 J. P. Cumalat,146 W. T. Fo r d,146
F. Jensen,146 A. Johnson,146 M. Krohn,146 E. MacDonald,146 T. Mulholland,146 R. Patel,146 A. Perloff,146 K. Stenson,146
K. A. Ulmer,146 S. R. Wagner,146 J. Alexander,147 J. Chaves,147 Y. Cheng,147 J. Chu,147 A. Datta,147 K. Mcdermott,147
N. Mirman,147 J. R. Patterson,147 D. Quach,147 A. Rinkevicius,147 A. Ryd,147 L. Skinnari,147 L. Sofﬁ,147 S. M. Tan,147 Z. Tao,147
J. Thom,147 J. Tucker,147 P. Wittich,147 M. Zientek,147 S. Abdullin,148 M. Albrow,148 M. Alyari,148 G. Apollinari,148
A. Apresyan,148 A. Apyan,148 S. Banerjee,148 L. A. T. Bauerdick,148 A. Beretvas,148 J. Berryhill,148 P. C. Bhat,148 K. Burkett,148
J. N. Butler,148 A. Canepa,148 G. B. Cerati,148 H. W. K. Cheung,148 F. Chlebana,148 M. Cremonesi,148 J. Duarte,148
V. D. E l v i ra ,148 J. Freeman,148 Z. Gecse,148 E. Gottschalk,148 L. Gray,148 D. Green,148 S. Grünendahl,148 O. Gutsche,148
J. Hanlon,148 R. M. Harris,148 S. Hasegawa,148 J. Hirschauer,148 Z. Hu,148 B. Jayatilaka,148 S. Jindariani,148 M. Johnson,148
U. Joshi,148 B. Klima,148 M. J. Kortelainen,148 B. Kreis,148 S. Lammel,148 D. Lincoln,148 R. Lipton,148 M. Liu,148 T. Liu,148
J. Lykken,148 K. Maeshima,148 J. M. Marrafﬁno,148 D. Mason,148 P. McBride,148 P. Me rke l, 148 S. Mrenna,148 S. Nahn,148
V. O’Dell,148 K. Pedro,148 C. Pena,148 O. Prokofyev,148 G. Rakness,148 L. Ristori,148 A. Savoy-Navarro,148,bp B. Schneider,148
E. Sexton-Kennedy,148 A. Soha,148 W. J. Spalding,148 L. Spiegel,148 S. Stoynev,148 J. Strait,148 N. Strobbe,148 L. Taylor,148
S. Tkaczyk,148 N. V. Tran,148 L. Uplegger,148 E. W. Vaandering,148 C. Vernieri,148 M. Verzocchi,148 R. Vidal,148 M. Wang,148
H. A. Weber,148 A. Whitbeck,148 D. Acosta,149 P. Avery,149 P. Bortignon,149 D. Bourilkov,149 A. Brinkerhoff,149
L. Cadamuro,149 A. Carnes,149 M. Carver,149 D. Curry,149 R. D. Field,149 S. V. Gleyzer,149 B. M. Joshi,149 J. Konigsberg,149
A. Korytov,149 K. H. Lo,149 P. Ma ,149 K. Matchev,149 H. Mei,149 G. Mitselmakher,149 D. Rosenzweig,149 K. Shi,149
D. Sperka,149 J. Wang,149 S. Wang,149 X. Zuo,149 Y. R. Joshi,150 S. Linn,150 A. Ackert,151 T. Adams,151 A. Askew,151
S. Hagopian,151 V. Hagopian,151 K. F. Johnson,151 T. Kolberg,151 G. Martinez,151 T. Perry,151 H. Prosper,151 A. Saha,151
C. Schiber,151 R. Yohay,151 M. M. Baarmand,152 V. Bhopatkar,152 S. Colafranceschi,152 M. Hohlmann,152 D. Noonan,152
M. Rahmani,152 T. Roy,152 F. Yumiceva,152 M. R. Adams,153 L. Apanasevich,153 D. Berry,153 R. R. Betts,153 R. Cavanaugh,153
X. Chen,153 S. Dittmer,153 O. Evdokimov,153 C. E. Gerber,153 D. A. Hangal,153 D. J. Hofman,153 K. Jung,153 J. Kamin,153
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C. Mills,153 I. D. Sandoval Gonzalez,153 M. B. Tonjes,153 H. Trauger,153 N. Varelas,153 H. Wang,153 X. Wang,153 Z. Wu,153
J. Zhang,153 M. Alhusseini,154 B. Bilki,154,bq W. Clarida,154 K. Dilsiz,154,br S. Durgut,154 R. P. Gandrajula,154
M. Haytmyradov,154 V. Khristenko,154 J.-P. Merlo,154 A. Mestvirishvili,154 A. Moeller,154 J. Nachtman,154 H. Ogul,154,bs
Y. Onel,154 F. Ozok,154,bt A. Penzo,154 C. Snyder,154 E. Tiras,154 J. Wetzel,154 B. Blumenfeld,155 A. Cocoros,155 N. Eminizer,155
D. Fehling,155 L. Feng,155 A. V. Gritsan,155 W. T. Hung,155 P. Maksimovic,155 J. Roskes,155 U. Sarica,155 M. Swartz,155
M. Xiao,155 C. You,155 A. Al-bataineh,156 P. Baringer,156 A. Bean,156 S. Boren,156 J. Bowen,156 A. Bylinkin,156 J. Castle,156
S. Khalil,156 A. Kropivnitskaya,156 D. Majumder,156 W. Mcbrayer,156 M. Murray,156 C. Rogan,156 S. Sanders,156 E. Schmitz,156
J. D. Tapia Takaki,156 Q. Wang,156 S. Duric,157 A. Ivanov,157 K. Kaadze,157 D. Kim,157 Y. Maravin,157 D. R. Mendis,157
T. Mitchell,157 A. Modak,157 A. Mohammadi,157 L. K. Saini,157 N. Skhirtladze,157 F. Rebassoo,158 D. Wright,158 A. Baden,159
O. Baron,159 A. Belloni,159 S. C. Eno,159 Y. Feng,159 C. Ferraioli,159 N. J. Hadley,159 S. Jabeen,159 G. Y. Jeng,159
R. G. Kellogg,159 J. Kunkle,159 A. C. Mignerey,159 S. Nabili,159 F. Ricci-Tam,159 Y. H. Shin,159 A. Skuja,159 S. C. Tonwar,159
K. Wong,159 D. Abercrombie,160 B. Allen,160 V. Azzolini,160 A. Baty,160 G. Bauer,160 R. Bi,160 S. Brandt,160 W. Busza,160
I. A. Cali,160 M. D’Alfonso,160 Z. Demiragli,160 G. Gomez Ceballos,160 M. Goncharov,160 P. Harris,160 D. Hsu,160 M. Hu,160
Y. Iiyama,160 G. M. Innocenti,160 M. Klute,160 D. Kovalskyi,160 Y.-J. Lee,160 P. D. Luckey,160 B. Maier,160 A. C. Marini,160
C. Mcginn,160 C. Mironov,160 S. Narayanan,160 X. Niu,160 C. Paus,160 C. Roland,160 G. Roland,160 G. S. F. Stephans,160
K. Sumorok,160 K. Tatar,160 D. Velicanu,160 J. Wang,160 T. W. Wang,160 B. Wyslouch,160 S. Zhaozhong,160
A. C. Benvenuti,161,bu R. M. Chatterjee,161 A. Evans,161 P. Hansen,161 Sh. Jain,161 S. Kalafut,161 Y. Kubota,161 Z. Lesko,161
J. Mans,161 N. Ruckstuhl,161 R. Rusack,161 J. Turkewitz,161 M. A. Wadud,161 J. G. Acosta,162 S. Oliveros,162 E. Avdeeva,163
K. Bloom,163 D. R. Claes,163 C. Fangmeier,163 F. Go l f , 163 R. Gonzalez Suarez,163 R. Kamalieddin,163 I. Kravchenko,163
J. Monroy,163 J. E. Siado,163 G. R. Snow,163 B. Stieger,163 A. Godshalk,164 C. Harrington,164 I. Iashvili,164 A. Kharchilava,164
C. Mclean,164 D. Nguyen,164 A. Parker,164 S. Rappoccio,164 B. Roozbahani,164 G. Alverson,165 E. Barberis,165 C. Freer,165
A. Hortiangtham,165 D. M. Morse,165 T. Orimoto,165 R. Teixeira De Lima,165 T. Wamorkar,165 B. Wang,165 A. Wisecarver,165
D. Wood,165 S. Bhattacharya,166 O. Charaf,166 K. A. Hahn,166 N. Mucia,166 N. Odell,166 M. H. Schmitt,166 K. Sung,166
M. Trovato,166 M. Velasco,166 R. Bucci,167 N. Dev,167 M. Hildreth,167 K. Hurtado Anampa,167 C. Jessop,167 D. J. Karmgard,167
N. Kellams,167 K. Lannon,167 W. Li ,167 N. Loukas,167 N. Marinelli,167 F. Meng,167 C. Mueller,167 Y. Musienko,167,bv
M. Planer,167 A. Reinsvold,167 R. Ruchti,167 P. Siddireddy,167 G. Smith,167 S. Taroni,167 M. Wayne,167 A. Wightman,167
M. Wolf,167 A. Woodard,167 J. Alimena,168 L. Antonelli,168 B. Bylsma,168 L. S. Durkin,168 S. Flowers,168 B. Francis,168
A. Hart,168 C. Hill,168 W. Ji,168 T. Y. Ling,168 W. Luo,168 B. L. Winer,168 S. Cooperstein,169 P. El m er , 169 J. Hardenbrook,169
S. Higginbotham,169 A. Kalogeropoulos,169 D. Lange,169 M. T. Lucchini,169 J. Luo,169 D. Marlow,169 K. Mei,169 I. Ojalvo,169
J. Olsen,169 C. Palmer,169 P. Piroué,169 J. Salfeld-Nebgen,169 D. Stickland,169 C. Tully,169 S. Malik,170 S. Norberg,170
A. Barker,171 V. E. Barnes,171 S. Das,171 L. Gutay,171 M. Jones,171 A. W. Jung,171 A. Khatiwada,171 B. Mahakud,171
D. H. Miller,171 N. Neumeister,171 C. C. Peng,171 S. Piperov,171 H. Qiu,171 J. F. Schulte,171 J. Sun,171 F. Wang,171 R. Xiao,171
W. Xie,171 T. Cheng,172 J. Dolen,172 N. Parashar,172 Z. Chen,173 K. M. Ecklund,173 S. Freed,173 F. J. M. Geurts,173
M. Kilpatrick,173 W. Li,173 B. P. Padley,173 R. Redjimi,173 J. Roberts,173 J. Rorie,173 W. Shi,173 Z. Tu,173 J. Zabel,173
A. Zhang,173 A. Bodek,174 P. de Barbaro,174 R. Demina,174 Y. t. Duh,174 J. L. Dulemba,174 C. Fallon,174 T. Ferbel,174
M. Galanti,174 A. Garcia-Bellido,174 J. Han,174 O. Hindrichs,174 A. Khukhunaishvili,174 P. Tan,174 R. Taus,174 A. Agapitos,175
J. P. Chou,175 Y. Gershtein,175 E. Halkiadakis,175 M. Heindl,175 E. Hughes,175 S. Kaplan,175 R. Kunnawalkam Elayavalli,175
S. Kyriacou,175 A. Lath,175 R. Montalvo,175 K. Nash,175 M. Osherson,175 H. Saka,175 S. Salur,175 S. Schnetzer,175
D. Shefﬁeld,175 S. Somalwar,175 R. Stone,175 S. Thomas,175 P. Thomassen,175 M. Walker,175 A. G. Delannoy,176 J. Heideman,176
G. Riley,176 S. Spanier,176 O. Bouhali,177,bw A. Celik,177 M. Dalchenko,177 M. De Mattia,177 A. Delgado,177 S. Dildick,177
R. Eusebi,177 J. Gilmore,177 T. Huang,177 T. Kamon,177,bx S. Luo,177 R. Mueller,177 D. Overton,177 L. Perniè,177 D. Rathjens,177
A. Safonov,177 N. Akchurin,178 J. Damgov,178 F. De Guio,178 P. R. Dudero,178 S. Kunori,178 K. Lamichhane,178 S. W. Lee,178
T. Mengke,178 S. Muthumuni,178 T. Peltola,178 S. Undleeb,178 I. Volobouev,178 Z. Wang,178 S. Greene,179 A. Gurrola,179
R. Janjam,179 W. Johns,179 C. Maguire,179 A. Melo,179 H. Ni,179 K. Padeken,179 J. D. Ruiz Alvarez,179 P. Sheldon,179 S. Tuo,179
J. Velkovska,179 M. Verweij,179 Q. Xu,179 M. W. Arenton,180 P. Ba rr i a, 180 B. Cox,180 R. Hirosky,180 M. Joyce,180
A. Ledovskoy,180 H. Li,180 C. Neu,180 T. Sinthuprasith,180 Y. Wang,180 E. Wolfe,180 F. Xia,180 R. Harr,181 P. E. Karchin,181
N. Poudyal,181 J. Sturdy,181 P. Thapa,181 S. Zaleski,181 M. Brodski,182 J. Buchanan,182 C. Caillol,182 D. Carlsmith,182
S. Dasu,182 L. Dodd,182 B. Gomber,182 M. Grothe,182 M. Herndon,182 A. Hervé,182 U. Hussain,182 P. Klabbers,182 A. Lanaro,182
K. Long,182 R. Loveless,182 T. Ruggles,182 A. Savin,182 V. Sharma,182 N. Smith,182 W. H. Smith,182 and N. Woods182
(CMS Collaboration)
1Yerevan Physics Institute, Yerevan, Armenia
2Institut für Hochenergiephysik, Wien, Austria
3Institute for Nuclear Problems, Minsk, Belarus
4Universiteit Antwerpen, Antwerpen, Belgium
5Vrije Universiteit Brussel, Brussel, Belgium
6Université Libre de Bruxelles, Bruxelles, Belgium
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A. M. SIRUNYAN et al. PHYSICAL REVIEW C 100, 044902 (2019)

7Ghent University, Ghent, Belgium

8Université Catholique de Louvain, Louvain-la-Neuve, Belgium

9Centro Brasileiro de Pesquisas Fisicas, Rio de Janeiro, Brazil

10Universidade do Estado do Rio de Janeiro, Rio de Janeiro, Brazil

11aUniversidade Estadual Paulista, São Paulo, Brazil

11b Universidade Federal do ABC, São Paulo, Brazil

12Institute for Nuclear Research and Nuclear Energy, Bulgarian Academy of Sciences, Soﬁa, Bulgaria

13University of Soﬁa, Soﬁa, Bulgaria

14Beihang University, Beijing, China

15Institute of High Energy Physics, Beijing, China

16State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing, China

17Tsinghua University, Beijing, China

18Universidad de Los Andes, Bogota, Colombia

19University of Split, Faculty of Electrical Engineering, Mechanical Engineering and Naval Architecture, Split, Croatia

20University of Split, Faculty of Science, Split, Croatia

21Institute Rudjer Boskovic, Zagreb, Croatia

22University of Cyprus, Nicosia, Cyprus

23Charles University, Prague, Czech Republic

24Escuela Politecnica Nacional, Quito, Ecuador

25Universidad San Francisco de Quito, Quito, Ecuador

26Academy of Scientiﬁc Research and Technology of the Arab Republic of Egypt, Egyptian Network of High Energy Physics, Cairo, Egypt

27National Institute of Chemical Physics and Biophysics, Tallinn, Estonia

28Department of Physics, University of Helsinki, Helsinki, Finland

29Helsinki Institute of Physics, Helsinki, Finland

30Lappeenranta University of Technology, Lappeenranta, Finland

31IRFU, CEA, Université Paris-Saclay, Gif-sur-Yvette, France

32Laboratoire Leprince-Ringuet, Ecole polytechnique, CNRS/IN2P3, Université Paris-Saclay, Palaiseau, France

33Université de Strasbourg, CNRS, IPHC UMR 7178, Strasbourg, France

34Centre de Calcul de l’Institut National de Physique Nucleaire et de Physique des Particules, CNRS/IN2P3, Villeurbanne, France

35Université de Lyon, Université Claude Bernard Lyon 1, CNRS-IN2P3, Institut de Physique Nucléaire de Lyon, Villeurbanne, France

36Georgian Technical University, Tbilisi, Georgia

37Tbilisi State University, Tbilisi, Georgia

38RWTH Aachen University, I. Physikalisches Institut, Aachen, Germany

39RWTH Aachen University, III. Physikalisches Institut A, Aachen, Germany

40RWTH Aachen University, III. Physikalisches Institut B, Aachen, Germany

41Deutsches Elektronen-Synchrotron, Hamburg, Germany

42University of Hamburg, Hamburg, Germany

43Karlsruher Institut fuer Technologie, Karlsruhe, Germany

44Institute of Nuclear and Particle Physics (INPP), NCSR Demokritos, Aghia Paraskevi, Greece

45National and Kapodistrian University of Athens, Athens, Greece

46National Technical University of Athens, Athens, Greece

47University of Ioánnina, Ioánnina, Greece

48MTA-ELTE Lendület CMS Particle and Nuclear Physics Group, Eötvös Loránd University, Budapest, Hungary

49Wigner Research Centre for Physics, Budapest, Hungary

50Institute of Nuclear Research ATOMKI, Debrecen, Hungary

51Institute of Physics, University of Debrecen, Debrecen, Hungary

52Indian Institute of Science (IISc), Bangalore, India

53National Institute of Science Education and Research, HBNI, Bhubaneswar, India

54Panjab University, Chandigarh, India

55University of Delhi, Delhi, India

56Saha Institute of Nuclear Physics, HBNI, Kolkata, India

57Indian Institute of Technology Madras, Madras, India

58Bhabha Atomic Research Centre, Mumbai, India

59Tata Institute of Fundamental Research-A, Mumbai, India

60Tata Institute of Fundamental Research-B, Mumbai, India

61Indian Institute of Science Education and Research (IISER), Pune, India

62Institute for Research in Fundamental Sciences (IPM), Tehran, Iran

63University College Dublin, Dublin, Ireland

64aINFN Sezione di Bari, Bari, Italy

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64bUniversità di Bari, Bari, Italy

64cPolitecnico di Bari, Bari, Italy

65aINFN Sezione di Bologna, Bologna, Italy

65bUniversità di Bologna, Bologna, Italy

66aINFN Sezione di Catania, Catania, Italy

66bUniversità di Cataniab, Catania, Italy

67aINFN Sezione di Firenze, Firenze, Italy

67bUniversità di Firenze, Firenze, Italy

68INFN Laboratori Nazionali di Frascati, Frascati, Italy

69aINFN Sezione di Genova, Genova, Italy

69bUniversità di Genova, Genova, Italy

70aINFN Sezione di Milano-Bicocca, Milano, Italy

70bUniversità di Milano-Bicocca, Milano, Italy

71aINFN Sezione di Napoli, Napoli, Italy

71bUniversità di Napoli ‘Federico II’, Napoli, Italy

71cUniversità della Basilicata, Potenza, Italy

71dUniversità G. Marconi, Roma, Italy

72aINFN Sezione di Padova, Padova, Italy

72bUniversità di Padova, Padova, Italy

72cUniversità di Trento, Trento, Italy

73aINFN Sezione di Pavia, Pavia, Italy

73bUniversità di Pavia, Pavia, Italy

74aINFN Sezione di Perugia, Perugia, Italy

74bUniversità di Perugia, Perugia, Italy

75aINFN Sezione di Pisa, Pisa, Italy

75bUniversità di Pisa, Pisa, Italy

75cScuola Normale Superiore di Pisa, Pisa, Italy

76aINFN Sezione di Roma, Rome, Italy

76bSapienza Università di Roma, Rome, Italy

77aINFN Sezione di Torino, Torino, Italy

77bUniversità di Torino, Torino, Italy

77cUniversità del Piemonte Orientale, Novara, Italy

78aINFN Sezione di Trieste, Trieste, Italy

78bUniversità di Trieste, Trieste, Italy

79Kyungpook National University, Daegu, Korea

80Chonnam National University, Institute for Universe and Elementary Particles, Kwangju, Korea

81Hanyang University, Seoul, Korea

82Korea University, Seoul, Korea

83Sejong University, Seoul, Korea

84Seoul National University, Seoul, Korea

85University of Seoul, Seoul, Korea

86Sungkyunkwan University, Suwon, Korea

87Vilnius University, Vilnius, Lithuania

88National Centre for Particle Physics, Universiti Malaya, Kuala Lumpur, Malaysia

89Universidad de Sonora (UNISON), Hermosillo, Mexico

90Centro de Investigacion y de Estudios Avanzados del IPN, Mexico City, Mexico

91Universidad Iberoamericana, Mexico City, Mexico

92Benemerita Universidad Autonoma de Puebla, Puebla, Mexico

93Universidad Autónoma de San Luis Potosí, San Luis Potosí, Mexico

94University of Auckland, Auckland, New Zealand

95University of Canterbury, Christchurch, New Zealand

96National Centre for Physics, Quaid-I-Azam University, Islamabad, Pakistan

97National Centre for Nuclear Research, Swierk, Poland

98Institute of Experimental Physics, Faculty of Physics, University of Warsaw, Warsaw, Poland

99Laboratório de Instrumentação e Física Experimental de Partículas, Lisboa, Portugal

100Joint Institute for Nuclear Research, Dubna, Russia

101Petersburg Nuclear Physics Institute, Gatchina (St. Petersburg), Russia

102Institute for Nuclear Research, Moscow, Russia

103Institute for Theoretical and Experimental Physics, Moscow, Russia

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104Moscow Institute of Physics and Technology, Moscow, Russia

105National Research Nuclear University ’Moscow Engineering Physics Institute’ (MEPhI), Moscow, Russia

106P. N. Lebedev Physical Institute, Moscow, Russia

107Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, Moscow, Russia

108Novosibirsk State University (NSU), Novosibirsk, Russia

109Institute for High Energy Physics of National Research Centre ’Kurchatov Institute’, Protvino, Russia

110National Research Tomsk Polytechnic University, Tomsk, Russia

111University of Belgrade, Faculty of Physics and Vinca Institute of Nuclear Sciences, Belgrade, Serbia

112Centro de Investigaciones Energéticas Medioambientales y Tecnológicas (CIEMAT), Madrid, Spain

113Universidad Autónoma de Madrid, Madrid, Spain

114Universidad de Oviedo, Oviedo, Spain

115Instituto de Física de Cantabria (IFCA), CSIC-Universidad de Cantabria, Santander, Spain

116University of Ruhuna, Department of Physics, Matara, Sri Lanka

117CERN, European Organization for Nuclear Research, Geneva, Switzerland

118Paul Scherrer Institut, Villigen, Switzerland

119ETH Zurich - Institute for Particle Physics and Astrophysics (IPA), Zurich, Switzerland

120Universität Zürich, Zurich, Switzerland

121National Central University, Chung-Li, Taiwan

122National Taiwan University (NTU), Taipei, Taiwan

123Chulalongkorn University, Faculty of Science, Department of Physics, Bangkok, Thailand

124Çukurova University, Physics Department, Science and Art Faculty, Adana, Turkey

125Middle East Technical University, Physics Department, Ankara, Turkey

126Bogazici University, Istanbul, Turkey

127Istanbul Technical University, Istanbul, Turkey

128Institute for Scintillation Materials of National Academy of Science of Ukraine, Kharkov, Ukraine

129National Scientiﬁc Center, Kharkov Institute of Physics and Technology, Kharkov, Ukraine

130University of Bristol, Bristol, United Kingdom

131Rutherford Appleton Laboratory, Didcot, United Kingdom

132Imperial College, London, United Kingdom

133Brunel University, Uxbridge, United Kingdom

134Baylor University, Waco, Texas, USA

135Catholic University of America, Washington, DC, USA

136The University of Alabama, Tuscaloosa, Alabama, USA

137Boston University, Boston, Massachusetts, USA

138Brown University, Providence, Rhode Island, USA

139University of California, Davis, Davis, California, USA

140University of California, Los Angeles, California, USA

141University of California, Riverside, Riverside, California, USA

142University of California, San Diego, La Jolla, California, USA

143Department of Physics, University of California, Santa Barbara, Santa Barbara, California, USA

144California Institute of Technology, Pasadena, California, USA

145Carnegie Mellon University, Pittsburgh, Pennsylvania, USA

146University of Colorado Boulder, Boulder, Colorado, USA

147Cornell University, Ithaca, New York, USA

148Fermi National Accelerator Laboratory, Batavia, Illinois, USA

149University of Florida, Gainesville, Florida, USA

150Florida International University, Miami, Florida, USA

151Florida State University, Tallahassee, Florida, USA

152Florida Institute of Technology, Melbourne, Florida, USA

153University of Illinois at Chicago (UIC), Chicago, Illinois, USA

154The University of Iowa, Iowa City, Iowa, USA

155Johns Hopkins University, Baltimore, Maryland, USA

156The University of Kansas, Lawrence, Kansas, USA

157Kansas State University, Manhattan, Kansas, USA

158Lawrence Livermore National Laboratory, Livermore, California, USA

159University of Maryland, College Park, Maryland, USA

160Massachusetts Institute of Technology, Cambridge, Massachusetts, USA

161University of Minnesota, Minneapolis, Minnesota, USA

162University of Mississippi, Oxford, Mississippi, USA

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163University of Nebraska-Lincoln, Lincoln, Nebraska, USA

164State University of New York at Buffalo, Buffalo, New York, USA

165Northeastern University, Boston, Massachusetts, USA

166Northwestern University, Evanston, Illinois, USA

167University of Notre Dame, Notre Dame, Indiana, USA

168The Ohio State University, Columbus, Ohio, USA

169Princeton University, Princeton, New Jersey, USA

170University of Puerto Rico, Mayaguez, Puerto Rico, USA

171Purdue University, West Lafayette, Indiana, USA

172Purdue University Northwest, Hammond, Indiana, USA

173Rice University, Houston, Texas, USA

174University of Rochester, Rochester, New York, USA

175Rutgers, The State University of New Jersey, Piscataway, New Jersey, USA

176University of Tennessee, Knoxville, Tennessee, USA

177Texas A&M University, College Station, Texas, USA

178Texas Tech University, Lubbock, Texas, USA

179Vanderbilt University, Nashville, Tennessee, USA

180University of Virginia, Charlottesville, Virginia, USA

181Wayne State University, Detroit, Michigan, USA

182University of Wisconsin - Madison, Madison, Wisconsin, USA

aAlso at Vienna University of Technology, Vienna, Austria.

bAlso at Vienna University of Technology, Vienna, Austria.

cAlso at IRFU, CEA, Université Paris-Saclay, Gif-sur-Yvette, France.

dAlso at Universidade Estadual de Campinas, Campinas, Brazil.

eAlso at Federal University of Rio Grande do Sul, Porto Alegre, Brazil.

fAlso at Université Libre de Bruxelles, Bruxelles, Belgium.

gAlso at University of Chinese Academy of Sciences, Beijing, China.

hAlso at Institute for Theoretical and Experimental Physics, Moscow, Russia.

iAlso at Joint Institute for Nuclear Research, Dubna, Russia.

jNow at Cairo University, Cairo, Egypt.

kNow at Fayoum University, El-Fayoum, Egypt, Cairo, Egypt; Now at British University in Egypt, Cairo, Egypt.

lNow at Fayoum University, El-Fayoum, Egypt.

mAlso at Department of Physics, King Abdulaziz University, Jeddah, Saudi Arabia.

nAlso at Université de Haute Alsace, Mulhouse, France.

oAlso at Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, Moscow, Russia.

pAlso at CERN, European Organization for Nuclear Research, Geneva, Switzerland.

qAlso at RWTH Aachen University, III. Physikalisches Institut A, Aachen, Germany.

rAlso at University of Hamburg, Hamburg, Germany.

sAlso at Brandenburg University of Technology, Cottbus, Germany.

tAlso at MTA-ELTE Lendület CMS Particle and Nuclear Physics Group, Eötvös Loránd University, Budapest, Hungary.

uAlso at Institute of Nuclear Research ATOMKI, Debrecen, Hungary.

vAlso at MTA-ELTE Lendület CMS Particle and Nuclear Physics Group, Eötvös Loránd University, Budapest, Hungary; Deceased.

wAlso at Institute of Physics, University of Debrecen, Debrecen, Hungary.

xAlso at Indian Institute of Technology Bhubaneswar, Bhubaneswar, India.

yAlso at Institute of Physics, Bhubaneswar, India.

zAlso at Shoolini University, Solan, India.

aaAlso at University of Visva-Bharati, Santiniketan, India.

abAlso at Isfahan University of Technology, Isfahan, Iran.

acAlso at Plasma Physics Research Center, Science and Research Branch, Islamic Azad University, Tehran, Iran.

adAlso at Università degli Studi di Siena, Siena, Italy.

aeAlso at Kyunghee University, Seoul, Korea.

afAlso at International Islamic University of Malaysia, Kuala Lumpur, Malaysia.

agAlso at Malaysian Nuclear Agency, MOSTI, Kajang, Malaysia.

ahAlso at Consejo Nacional de Ciencia y Tecnología, Mexico City, Mexico.

aiAlso at Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland.

ajAlso at Institute for Nuclear Research, Moscow, Russia; Now at National Research Nuclear University ’Moscow Engineering Physics

Institute’ (MEPhI), Moscow, Russia.

akAlso at St. Petersburg State Polytechnical University, St. Petersburg, Russia.

alAlso at University of Florida, Gainesville, USA.

044902-21

A. M. SIRUNYAN et al. PHYSICAL REVIEW C 100, 044902 (2019)

amAlso at P. N. Lebedev Physical Institute, Moscow, Russia.

anAlso at National Research Nuclear University ’Moscow Engineering Physics Institute’ (MEPhI), Moscow, Russia.

aoAlso at INFN Sezione di Padova, Padova, Italy; Università di Padova, Padova, Italy; Università di Trento (Trento), Padova, Italy.

apAlso at Budker Institute of Nuclear Physics, Novosibirsk, Russia.

aqAlso at Faculty of Physics, University of Belgrade, Belgrade, Serbia.

arAlso at INFN Sezione di Pavia, Pavia, Italy; Università di Pavia, Pavia, Italy.

asAlso at University of Belgrade, Faculty of Physics and Vinca Institute of Nuclear Sciences, Belgrade, Serbia.

atAlso at Scuola Normale e Sezione dell’INFN, Pisa, Italy.

auAlso at National and Kapodistrian University of Athens, Athens, Greece.

avAlso at Riga Technical University, Riga, Latvia.

awAlso at Universität Zürich, Zurich, Switzerland.

axAlso at Stefan Meyer Institute for Subatomic Physics (SMI), Vienna, Austria.

ayAlso at Istanbul Aydin University, Istanbul, Turkey.

azAlso at Mersin University, Mersin, Turkey.

baAlso at Piri Reis University, Istanbul, Turkey.

bbAlso at Adiyaman University, Adiyaman, Turkey.

bcAlso at Ozyegin University, Istanbul, Turkey.

bdAlso at Izmir Institute of Technology, Izmir, Turkey.

beAlso at Marmara University, Istanbul, Turkey.

bfAlso at Kafkas University, Kars, Turkey.

bgAlso at Istanbul University, Faculty of Science, Istanbul, Turkey.

bhAlso at Istanbul Bilgi University, Istanbul, Turkey.

biAlso at Hacettepe University, Ankara, Turkey.

bjAlso at Rutherford Appleton Laboratory, Didcot, United Kingdom.

bkAlso at School of Physics and Astronomy, University of Southampton, Southampton, United Kingdom.

blAlso at Monash University, Faculty of Science, Clayton, Australia.

bmAlso at Bethel University, St. Paul, USA.

bnAlso at Karamano ˘

glu Mehmetbey University, Karaman, Turkey.

boAlso at Utah Valley University, Orem, USA.

bpAlso at Purdue University, West Lafayette, USA.

bqAlso at Beykent University, Istanbul, Turkey.

brAlso at Bingol University, Bingol, Turkey.

bsAlso at Sinop University, Sinop, Turkey.

btAlso at Mimar Sinan University, Istanbul, Istanbul, Turkey.

buDeceased.

bvAlso at Institute for Nuclear Research, Moscow, Russia.

bwAlso at Texas A&M University at Qatar, Doha, Qatar.

bxAlso at Kyungpook National University, Daegu, Korea.

044902-22

Higher-order anisotropic flow correlations in Xe-Xe collisions at $\mathrm{\sqrt{s_{NN}}= 5.44 TeV}

Preprint

May 2025

By employing the Monte Carlo HYDJET++ model (HYDrodynamics plus JETs), we produce anisotropic harmonic flow coefficients

v_n

(

n = 4

-7) in deformed Xe-Xe collisions at

\sqrt{s_{NN}} = 5.44~\mathrm{TeV}

. These harmonics are measured with respect to a plane constructed using the lower-order Fourier harmonics

v_2

and

v_3

, produced using the reaction plane method. The cross-talk between elliptic and triangular flows in the model generates both even and odd higher-order harmonics. By combining analyses of higher harmonics with those of

v_2

and

v_3

, one can eliminate uncertainties in modeling anisotropic flow from initial conditions and define quantities that involve only nonlinear hydrodynamic response coefficients. In this context, we study the individual response of higher-order flow coefficients to the lower-order ones through a power-law scaling technique of the form

v_n / v_m^m

, as a function of collision centrality. We report that the higher-order flow coefficients

v_n

(

n = 4

-7) exhibit strong centrality dependence and are significantly correlated with the elliptic and triangular flow. The results are compared with data from recent ALICE, ATLAS, and CMS experiments at the LHC.

Angular structure of many-body correlations in atomic nuclei: From nuclear deformations to diffractive vector meson production in

\gamma A

collisions

Preprint

Apr 2025

There is growing evidence that high-energy scattering processes involving nuclei can offer unique insights into the many-body correlations present in nuclear ground states, in particular those of deformed nuclei. These processes involve, for instance, the collective anisotropic flows in heavy-ion collisions, or the diffractive production of vector mesons in photo-nuclear (

\gamma A

) interactions. In this paper, we use a classical approximation and simple analytical models in order to exhibit characteristic and universal features of ground-state correlation functions that result from the presence of a deformed intrinsic state. In the case of a small axial quadrupole deformation, we show that the random rotation of the intrinsic density of the nucleus leads to a specific quadrupole modulation of the lab-frame two-body density as a function of the relative azimuthal angle. As a phenomenological, albeit academic application, we analyze the diffractive production of vector mesons in high-energy

\gamma+^8

Be collisions. This demonstrates with the simplest deformed nucleus how the two-body correlations impact the

|t|

dependence of the incoherent cross sections.

Revealing the harmonic structure of nuclear two-body correlations in high-energy heavy-ion collisions

Preprint

Apr 2025

Smashing nuclei at ultrarelativistic speeds and analyzing the momentum distribution of outgoing debris provides a powerful method to probe the many-body properties of the incoming nuclear ground states. Within a perturbative description of initial-state fluctuations in the quark-gluon plasma, we express the measurement of anisotropic flow in ultra-central heavy-ion collisions as the quantum-mechanical average of a specific set of operators measuring the harmonic structure of the two-body azimuthal correlations among nucleons in the colliding states. These observables shed a new light on spatial correlations in atomic nuclei, while enabling us to test the complementary pictures of nuclear structure delivered by low- and high-energy experiments on the basis of state-of-the-art theoretical approaches rooted in quantum chromodynamics.

Benchmarking nuclear matrix elements of

0\nu\beta\beta

decay with high-energy nuclear collisions

Preprint

Feb 2025

Reducing uncertainties in the nuclear matrix element (NME) remains a critical challenge in designing and interpreting experiments aimed at discovering neutrinoless double beta (

0\nu\beta\beta

) decay. Here, we identify a class of observables, distinct from those employed in low-energy nuclear structure applications, that are strongly correlated with the NME: momentum correlations among hadrons produced in high-energy nuclear collisions. Focusing on the

^{150}

\rightarrow

^{150}

Sm transition, we combine a Bayesian analysis of the structure of

^{150}

Nd with simulations of high-energy

^{150}

Nd+

^{150}

Nd collisions. We reveal prominent correlations between the NME and features of the quark-gluon plasma (QGP) formed in these processes, such as spatial gradients and anisotropies, which are accessible via collective flow measurements. Our findings demonstrate collider experiments involving

0\nu\beta\beta

decay candidates as a platform for benchmarking theoretical predictions of the NME.

Role of clustered nuclear geometry in particle production through p–C and p–O collisions at the Large Hadron Collider

Article

Jun 2025
EUR PHYS J A

Long-range multi-particle correlations in heavy-ion collisions have shown conclusive evidence of the hydrodynamic behavior of strongly interacting matter and are associated with the final-state azimuthal momentum anisotropy. In small collision systems, azimuthal anisotropy can be influenced by the hadronization mechanism and residual jet-like correlations. Thus, one of the motives of the planned p–O and O–O collisions at the LHC and RHIC is to understand the origin of small system collectivity. As the anisotropic flow coefficients (

v_n

) are sensitive to the initial-state effects including nuclear shape, deformation, and charge density profiles, studies involving

^{12}

C and

^{16}

O nuclei are transpiring due to the presence of exotic

\alpha

(

^{4}

He) clusters in such nuclei. In this study, for the first time, we investigate the effects of nuclear

\alpha

–clusters on the azimuthal anisotropy of the final-state hadrons in p–C and p–O collisions at

\sqrt{s_\textrm{NN}}= 9.9

TeV within a multi-phase transport model framework. We report the transverse momentum (

p_\textrm{T}

) and pseudorapidity (

\eta

) spectra, participant eccentricity (

\epsilon _2

) and triangularity (

\epsilon _3

), and estimate the elliptic flow (

v_2

) and triangular flow (

v_3

) of the final-state hadrons using the two-particle cumulant method. These results are compared with a model-independent Sum of Gaussians (SOG) type nuclear density profile for

^{12}

C and

^{16}

O nuclei.

Study of the hottest droplet of fluid through correlations and fluctuations of collective variables

Preprint

Full-text available

May 2025

Rupam Samanta

In this thesis, we focus on the fluctuations and correlations of the collective observables such as the mean transverse momentum per particle (

[p_T]

) and harmonic flow coefficients (

v_n

) of particles produced in the ultrarelativistic heavy-ion collisions at RHIC and the LHC. Specifically, we show that the fluctuations of harmonic flow can be probed by the factorization-breaking coefficients between flow vectors in different

p_T

-bins. Experimental difficulty can be reduced by taking one of the flow vectors momentum averaged. Fluctuations cause a decorrelation between the flow vectors, which can be attributed to equal contributions from the flow magnitude and flow angle decorrelation. We study fluctuations of mean transverse momentum per particle (

[p_T]

) in ultra-central collisions and show that our model can explain the steep fall of its variance observed by the ATLAS collaboration. We also present robust predictions for the skewness and kurtosis, and highlight the role of impact parameter fluctuations in ultracentral collisions. We study the Pearson correlation coefficients between

[p_T]

and

v_n^2

, which can map the initial state correlations between the shape and size of the fireball. We show that higher order normalized and symmetric cumulants between these observables can be constructed, which put useful additional constraints on the initial state properties. Furthermore, we study the momentum dependent Pearson correlation between

[p_T]

and the transverse momentum dependent flow. It shows sensitivity to the Gaussian width of the nucleon at the initial state. Finally, we show that such correlations and fluctuations of collective observables can be used to study nuclear deformation and put robust constraints on their deformation parameters through high energy nuclear collisions.

Azimuthal Anisotropy in Xe–Xe and Pb–Pb Collisions with the Monte Carlo Model HYDJET++ and the CMS Detector at the Energies of the LHC

Article

Feb 2025
Moscow Univ Phys Bull

Latest Results on Heavy-Ion Physics with the CMS Detector

Article

Feb 2025
Moscow Univ Phys Bull

S. V. Petrushanko

Impact of the pre-equilibrium stage for the determination of nuclear geometry in high-energy isobar collisions

Article

Dec 2024

Imaging shapes of atomic nuclei in high-energy nuclear collisions

Article

Full-text available

Nov 2024
NATURE

Atomic nuclei are self-organized, many-body quantum systems bound by strong nuclear forces within femtometre-scale space. These complex systems manifest a variety of shapes 1–3 , traditionally explored using non-invasive spectroscopic techniques at low energies 4,5 . However, at these energies, their instantaneous shapes are obscured by long-timescale quantum fluctuations, making direct observation challenging. Here we introduce the collective-flow-assisted nuclear shape-imaging method, which images the nuclear global shape by colliding them at ultrarelativistic speeds and analysing the collective response of outgoing debris. This technique captures a collision-specific snapshot of the spatial matter distribution within the nuclei, which, through the hydrodynamic expansion, imprints patterns on the particle momentum distribution observed in detectors 6,7 . We benchmark this method in collisions of ground-state uranium-238 nuclei, known for their elongated, axial-symmetric shape. Our findings show a large deformation with a slight deviation from axial symmetry in the nuclear ground state, aligning broadly with previous low-energy experiments. This approach offers a new method for imaging nuclear shapes, enhances our understanding of the initial conditions in high-energy collisions and addresses the important issue of nuclear structure evolution across energy scales.

Pseudorapidity and transverse momentum dependence of flow harmonics in p Pb and PbPb collisions

Article

Full-text available

Oct 2018

Measurements of azimuthal angular correlations are presented for high-multiplicity pPb collisions at sNN=5.02TeV and peripheral PbPb collisions at sNN=2.76TeV. The data used in this work were collected with the Compact Muon Solenoid (CMS) detector at the European Organization for Nuclear Research (CERN) Large Hadron Collider (LHC). Fourier coefficients as functions of transverse momentum and pseudorapidity are studied using the scalar product method; four-, six-, and eight-particle cumulants; and the Lee-Yang zero technique. The influence of event plane decorrelation is evaluated using the scalar product method and found to account for most of the observed pseudorapidity dependence.

Energy dependence and fluctuations of anisotropic flow in Pb-Pb collisions at s N N = 5.02

\sqrt{s_{\mathrm{NN}}}=5.02

and 2.76 TeV

Article

Full-text available

Jul 2018
J HIGH ENERGY PHYS

A bstract Measurements of anisotropic flow coefficients with two- and multi-particle cumulants for inclusive charged particles in Pb-Pb collisions at

\sqrt{s_{\mathrm{NN}}}=5.02

s N N = 5.02 and 2.76 TeV are reported in the pseudorapidity range | η | < 0.8 and transverse momentum 0.2 < p T < 50 GeV/ c . The full data sample collected by the ALICE detector in 2015 (2010), corresponding to an integrated luminosity of 12.7 (2.0) μ b ⁻¹ in the centrality range 0-80%, is analysed. Flow coefficients up to the sixth flow harmonic ( v 6 ) are reported and a detailed comparison among results at the two energies is carried out. The p T dependence of anisotropic flow coefficients and its evolution with respect to centrality and harmonic number n are investigated. An approximate power-law scaling of the form v n ( p T ) ∼ p T n /3 is observed for all flow harmonics at low p T (0.2 < p T < 3 GeV/ c ). At the same time, the ratios v n / v m n / m are observed to be essentially independent of p T for most centralities up to about p T = 10 GeV/ c . Analysing the differences among higher-order cumulants of elliptic flow ( v 2 ), which have different sensitivities to flow fluctuations, a measurement of the standardised skewness of the event-by-event v 2 distribution P ( v 2 ) is reported and constraints on its higher moments are provided. The Elliptic Power distribution is used to parametrise P ( v 2 ), extracting its parameters from fits to cumulants. The measurements are compared to different model predictions in order to discriminate among initial-state models and to constrain the temperature dependence of the shear viscosity to entropy-density ratio.

Anisotropic flow in Xe–Xe collisions at s NN = 5.44 TeV

Article

Full-text available

Jun 2018
PHYS LETT B

The first measurements of anisotropic flow coefficients vn for mid-rapidity charged particles in Xe–Xe collisions at sNN=5.44 TeV are presented. Comparing these measurements to those from Pb–Pb collisions at sNN=5.02 TeV, v2 is found to be suppressed for mid-central collisions at the same centrality, and enhanced for central collisions. The values of v3 are generally larger in Xe–Xe than in Pb–Pb at a given centrality. These observations are consistent with expectations from hydrodynamic predictions. When both v2 and v3 are divided by their corresponding eccentricities for a variety of initial state models, they generally scale with transverse density when comparing Xe–Xe and Pb–Pb, with some deviations observed in central Xe–Xe and Pb–Pb collisions. These results assist in placing strong constraints on both the initial state geometry and medium response for relativistic heavy-ion collisions.

Measurement of longitudinal flow decorrelations in Pb+Pb collisions at

\sqrt{s_{\text {NN}}}=2.76

sNN=2.76 and 5.02 TeV with the ATLAS detector

Article

Full-text available

Feb 2018

Measurements of longitudinal flow correlations are presented for charged particles in the pseudorapidity range

|\eta |<2.4

using 7 and 470 \upmu \hbox {b}^{-1} of Pb+Pb collisions at

\sqrt{s_{\text {NN}}}=2.76

and 5.02 TeV, respectively, recorded by the ATLAS detector at the LHC. It is found that the correlation between the harmonic flow coefficients

v_n

measured in two separated

\eta

intervals does not factorise into the product of single-particle coefficients, and this breaking of factorisation, or flow decorrelation, increases linearly with the

\eta

separation between the intervals. The flow decorrelation is stronger at 2.76 TeV than at 5.02 TeV. Higher-order moments of the correlations are also measured, and the corresponding linear coefficients for the

k{\text {th}}

-moment of the

v_n

are found to be proportional to k for

v_3

, but not for

v_2

. The decorrelation effect is separated into contributions from the magnitude of

v_n

and the event-plane orientation, each as a function of

\eta

. These two contributions are found to be comparable. The longitudinal flow correlations are also measured between

v_n

of different order in n. The decorrelations of

v_2

and

v_3

are found to be independent of each other, while the decorrelations of

v_4

and

v_5

are found to be driven by the nonlinear contribution from

v_2^2

and

v_2v_3

, respectively.

Measurement of long-range multiparticle azimuthal correlations with the subevent cumulant method in p p and p +Pb collisions with the ATLAS detector at the CERN Large Hadron Collider

Article

Full-text available

Feb 2018

A detailed study of multiparticle azimuthal correlations is presented using pp data at s=5.02 and 13 TeV, and p+Pb data at sNN=5.02 TeV, recorded with the ATLAS detector at the CERN Large Hadron Collider. The azimuthal correlations are probed using four-particle cumulants cn{4} and flow coefficients vn{4}=(−cn{4})1/4 for n=2 and 3, with the goal of extracting long-range multiparticle azimuthal correlation signals and suppressing the short-range correlations. The values of cn{4} are obtained as a function of the average number of charged particles per event, Nch, using the recently proposed two-subevent and three-subevent cumulant methods, and compared with results obtained with the standard cumulant method. The standard method is found to be strongly biased by short-range correlations, which originate mostly from jets with a positive contribution to cn{4}. The three-subevent method, on the other hand, is found to be least sensitive to short-range correlations. The three-subevent method gives a negative c2{4}, and therefore a well-defined v2{4}, nearly independent of Nch, which implies that the long-range multiparticle azimuthal correlations persist to events with low multiplicity. Furthermore, v2{4} is found to be smaller than the v2{2} measured using the two-particle correlation method, as expected for long-range collective behavior. Finally, the measured values of v2{4} and v2{2} are used to estimate the number of sources relevant for the initial eccentricity in the collision geometry. The results based on the subevent cumulant technique provide direct evidence, in small collision systems, for a long-range collectivity involving many particles distributed across a broad rapidity interval.

Hydrodynamic predictions for 5.44 TeV Xe+Xe collisions

Article

Full-text available

Nov 2017

We argue that relativistic hydrodynamics is able to make robust predictions for soft particle production in Xe+Xe collisions at the CERN Large Hadron Collider (LHC). The change of system size from Pb+Pb to Xe+Xe provides a unique opportunity to test the scaling laws inherent to fluid dynamics. Using event-by-event hydrodynamic simulations, we make quantitative predictions for several observables: Mean transverse momentum, anisotropic flow coefficients, and their fluctuations. Results are shown as function of collision centrality.

Relative flow fluctuations as a probe of initial state fluctuations

Article

Full-text available

Feb 2017

Elliptic flow,

v_2

, and triangular flow,

v_3

, are to a good approximation linearly proportional to the corresponding spatial anisotropies of the initial density profile,

\varepsilon_2

and

\varepsilon_3

. Using event-by-event hydrodynamic simulations, we point out when deviations from this linear scaling are to be expected. When these deviations are negligible, relative

v_n

fluctuations are equal to relative

\varepsilon_n

fluctuations, and one can directly probe models of initial conditions using ratios of cumulants, for instance

v_n\{4\}/v_n\{2\}

. We argue that existing models of initial conditions tend to overestimate flow fluctuations in central Pb+Pb collisions, and to underestimate them in peripheral collisions. We make predictions for

v_3\{6\}

in noncentral Pb+Pb collisions, and for

v_3\{4\}

and

v_3\{6\}

in high-multiplicity p+Pb collisions.

Evidence for collectivity in pp collisions at the LHC

Article

Full-text available

Dec 2016
PHYS LETT B

Measurements of two- and multi-particle angular correlations in pp collisions at s=5,7, and 13TeV are presented as a function of charged-particle multiplicity. The data, corresponding to integrated luminosities of 1.0pb−1 (5 TeV), 6.2pb−1 (7 TeV), and 0.7pb−1 (13 TeV), were collected using the CMS detector at the LHC. The second-order (v2) and third-order (v3) azimuthal anisotropy harmonics of unidentified charged particles, as well as v2 of KS0 and Λ/Λ‾ particles, are extracted from long-range two-particle correlations as functions of particle multiplicity and transverse momentum. For high-multiplicity pp events, a mass ordering is observed for the v2 values of charged hadrons (mostly pions), KS0, and Λ/Λ‾, with lighter particle species exhibiting a stronger azimuthal anisotropy signal below pT≈2GeV/c. For 13 TeV data, the v2 signals are also extracted from four- and six-particle correlations for the first time in pp collisions, with comparable magnitude to those from two-particle correlations. These observations are similar to those seen in pPb and PbPb collisions, and support the interpretation of a collective origin for the observed long-range correlations in high-multiplicity pp collisions.

3-D Glasma initial state for relativistic heavy ion collisions

Article

May 2016

We extend the impact parameter dependent Glasma model (IP-Glasma) to three dimensions using explicit small x evolution of the two incoming nuclear gluon distributions. We compute rapidity distributions of produced gluons and the early time energy momentum tensor as a function of space-time rapidity and transverse coordinates. We study rapidity correlations and fluctuations of the initial geometry and multiplicity distributions and compare to existing models for the three dimensional initial state.

Alternative ansatz to wounded nucleon and binary collision scaling in high-energy nuclear collisions

Article

Jul 2015

We introduce a new parametric initial-condition model for high-energy nuclear collisions based on eikonal entropy deposition via a "reduced-thickness" function. The model simultaneously describes experimental proton-proton, proton-nucleus, and nucleus-nucleus multiplicity distributions and generates nucleus-nucleus eccentricity harmonics consistent with experimental flow constraints. In addition, the model is compatible with ultracentral uranium-uranium data unlike existing models that include binary collision terms.

Charged-particle angular correlations in XeXe collisions at s N N = 5.44 TeV

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