-
H. Abramowicz,
I. Abt,
L. Adamczyk,
M. Adamus,
R. Aggarwal,
C. Alexa,
V. Andreev,
S. Antonelli,
P. Antonioli,
A. Antonov, [......],
W. Zeuner,
Z. Zhang,
B. O. Zhautykov,
N. Zhmak,
A. Zichichi,
R. Žlebčík,
H. Zohrabyan,
Z. Zolkapli,
F. Zomer,
D. S. Zotkin
[show abstract]
[hide abstract]
ABSTRACT: Measurements of open charm production cross sections in deep-inelastic ep
scattering at HERA from the H1 and ZEUS Collaborations are combined. Reduced
cross sections sigma_red^{c\bar{c}} for charm production are obtained in the
kinematic range of photon virtuality 2.5<Q2<2000 GeV2 and Bjorken scaling
variable 0.00003<x<0.05. The combination method accounts for the correlations
of the systematic uncertainties among the different data sets. The combined
charm data together with the combined inclusive deep-inelastic scattering cross
sections from HERA are used as input for a detailed NLO QCD analysis to study
the influence of different heavy flavour schemes on the parton distribution
functions. The optimal values of the charm mass as a parameter in these
different schemes are obtained. The implications on the NLO predictions for
W^{\pm} and Z production cross sections at the LHC are investigated. Using the
fixed flavour number scheme, the running mass of the charm quark is determined.
11/2012;
-
ZEUS collaboration,
H. Abramowicz,
I. Abt,
L. Adamczyk,
M. Adamus,
R. Aggarwal,
S. Antonelli,
P. Antonioli,
A. Antonov,
M. Arneodo, [......],
O. Zabiegalov,
A. F. Żarnecki,
L. Zawiejski,
O. Zenaiev,
W. Zeuner,
B. O. Zhautykov,
N. Zhmak,
A. Zichichi,
Z. Zolkapli,
D. S. Zotkin
[show abstract]
[hide abstract]
ABSTRACT: The production of Z0 bosons in the reaction ep -> eZ0p*, where p* stands for
a proton or a low-mass nucleon resonance, has been studied in ep collisions at
HERA using the ZEUS detector. The analysis is based on a data sample collected
between 1996 and 2007, amounting to 496 pb-1 of integrated luminosity. The Z0
was measured in the hadronic decay mode. The elasticity of the events was
ensured by a cut on eta_max < 3.0, where eta_max is the maximum pseudorapidity
of energy deposits in the calorimeter defined with respect to the proton beam
direction. A signal was observed at the Z0 mass. The cross section of the
reaction ep -> eZ0p* was measured to be sigma(ep -> eZ0p*) = 0.13 +/- 0.06
(stat.) +/- 0.01 (syst.) pb, in agreement with the Standard Model prediction of
0.16 pb. This is the first measurement of Z0 production in ep collisions.
10/2012;
-
ZEUS Collaboration,
H. Abramowicz,
I. Abt,
L. Adamczyk,
M. Adamus,
R. Aggarwal,
S. Antonelli,
P. Antonioli,
A. Antonov,
M. Arneodo, [......],
L. Zawiejski,
O. Zenaiev,
W. Zeuner,
B. O. Zhautykov,
N. Zhmak,
C. Zhou,
A. Zichichi,
Z. Zolkapli,
M. Zolko,
D. S. Zotkin
-
H. Abramowicz,
I. Abt,
L. Adamczyk,
M. Adamus,
R. Aggarwal,
S. Antonelli,
P. Antonioli,
A. Antonov,
M. Arneodo,
O. Arslan, [......],
A. F. Żarnecki,
L. Zawiejski,
O. Zenaiev,
W. Zeuner,
B. O. Zhautykov,
N. Zhmak,
C. Zhou,
A. Zichichi,
Z. Zolkapli,
D. S. Zotkin
[show abstract]
[hide abstract]
ABSTRACT: A search for first-generation leptoquarks was performed in electron-proton and positron-proton collisions recorded with the ZEUS detector at HERA in 2003–2007 using an integrated luminosity of 366 pb-1. Final states with an electron and jets or with missing transverse momentum and jets were analyzed, searching for resonances or other deviations from the standard model predictions. No evidence for any leptoquark signal was found. The data were combined with data previously taken at HERA, resulting in a total integrated luminosity of 498 pb-1. Limits on the Yukawa coupling, λ, of leptoquarks were set as a function of the leptoquark mass for different leptoquark types within the Buchmüller-Rückl-Wyler model. Leptoquarks with a coupling λ=0.3 are excluded for masses up to 699 GeV.
Phys. Rev. D. 07/2012; 86(1).
-
ZEUS Collaboration,
H. Abramowicz,
I. Abt,
L. Adamczyk,
M. Adamus,
R. Aggarwal,
S. Antonelli,
P. Antonioli,
A. Antonov,
M. Arneodo, [......],
A. F. Zarnecki,
L. Zawiejski,
O. Zenaiev,
W. Zeuner,
B. O. Zhautykov,
N. Zhmak,
C. Zhou,
A. Zichichi,
Z. Zolkapli,
D. S. Zotkin
[show abstract]
[hide abstract]
ABSTRACT: Inclusive-jet cross sections have been measured in the reaction ep->e+jet+X
for photon virtuality Q2 < 1 GeV2 and gamma-p centre-of-mass energies in the
region 142 < W(gamma-p) < 293 GeV with the ZEUS detector at HERA using an
integrated luminosity of 300 pb-1. Jets were identified using the kT, anti-kT
or SIScone jet algorithms in the laboratory frame. Single-differential cross
sections are presented as functions of the jet transverse energy, ETjet, and
pseudorapidity, etajet, for jets with ETjet > 17 GeV and -1 < etajet < 2.5. In
addition, measurements of double-differential inclusive-jet cross sections are
presented as functions of ETjet in different regions of etajet.
Next-to-leading-order QCD calculations give a good description of the
measurements, except for jets with low ETjet and high etajet. The influence of
non-perturbative effects not related to hadronisation was studied. Measurements
of the ratios of cross sections using different jet algorithms are also
presented; the measured ratios are well described by calculations including up
to O(alphas2) terms. Values of alphas(Mz) were extracted from the measurements
and the energy-scale dependence of the coupling was determined. The value of
alphas(Mz) extracted from the measurements based on the kT jet algorithm is
alphas(Mz) = 0.1206 +0.0023 -0.0022 (exp.) +0.0042 -0.0035 (th.); the results
from the anti-kT and SIScone algorithms are compatible with this value and have
a similar precision.
05/2012;
-
The ZEUS collaboration,
H. Abramowicz,
I. Abt,
L. Adamczyk,
M. Adamus,
R. Aggarwal,
S. Antonelli,
P. Antonioli,
A. Antonov,
M. Arneodo, [......],
L. Zawiejski,
O. Zenaiev,
W. Zeuner,
B. O. Zhautykov,
N. Zhmak,
C. Zhou,
A. Zichichi,
M. Zolko,
D. S. Zotkin,
Z. Zulkapli
[show abstract]
[hide abstract]
ABSTRACT: Measurements of the cross sections for charged current deep inelastic scattering in e
+
p collisions with a longitudinally polarised positron beam are presented. The measurements are based on a data sample with
an integrated luminosity of 132pb−1 collected with the ZEUS detector at HERA at a centre-of-mass energy of 318GeV. The total cross section is presented at positive
and negative values of the longitudinal polarisation of the positron beams. The single-differential cross-sections dσ/dQ
2, dσ/dx and dσ/dy are presented for Q
2>200GeV2. The reduced cross-section [(s)\tilde]\tilde{\sigma} is presented in the kinematic range 200<Q
2<60 000GeV2 and 0.006<x<0.562. The measurements agree well with the predictions of the Standard Model. The results are used to determine a lower
limit on the mass of a hypothetical right-handed W boson.
European Physical Journal C 04/2012; 70(4):945-963. · 3.63 Impact Factor
-
ZEUS Collaboration,
S. Chekanov,
M. Derrick,
S. Magill,
B. Musgrave,
D. Nicholass,
J. Repond,
R. Yoshida,
M. C. K. Mattingly,
P. Antonioli, [......],
E. Brownson,
D. D. Reeder,
A. A. Savin,
W. H. Smith,
H. Wolfe,
S. Bhadra,
C. D. Catterall,
G. Hartner,
U. Noor,
J. Whyte
[show abstract]
[hide abstract]
ABSTRACT: The proton-dissociative diffractive photoproduction of J/ψ mesons has been studied in ep collisions with the ZEUS detector at HERA using an integrated luminosity of 112 pb−1. The cross section is presented as a function of the photon-proton centre-of-mass energy and of the squared four-momentum
transfer at the proton vertex. The results are compared to perturbative QCD calculations.
KeywordsLepton-Nucleon Scattering
Journal of High Energy Physics 04/2012; 2010(5):1-36. · 5.83 Impact Factor
-
The ZEUS Collaboration,
H. Abramowicz,
I. Abt,
L. Adamczyk,
M. Adamus,
R. Aggarwal,
S. Antonelli,
P. Antonioli,
A. Antonov,
M. Arneodo, [......],
L. Zawiejski,
O. Zenaiev,
W. Zeuner,
B. O. Zhautykov,
N. Zhmak,
C. Zhou,
A. Zichichi,
M. Zolko,
D. S. Zotkin,
Z. Zulkapli
[show abstract]
[hide abstract]
ABSTRACT: Beauty production in deep inelastic scattering with events in which a muon and a jet are observed in the final state has been
measured with the ZEUS detector at HERA using an integrated luminosity of 114pb−1. The fraction of events with beauty quarks in the data was determined using the distribution of the transverse momentum of
the muon relative to the jet. The cross section for beauty production was measured in the kinematic range of photon virtuality,
Q
2>2GeV2, and inelasticity, 0.05<y<0.7, with the requirement of a muon and a jet. Total and differential cross sections are presented and compared to QCD predictions.
The beauty contribution to the structure function F
2 was extracted and is compared to theoretical predictions.
European Physical Journal C 04/2012; 69(3):347-360. · 3.63 Impact Factor
-
The ZEUS Collaboration,
H. Abramowicz,
I. Abt,
L. Adamczyk,
M. Adamus,
R. Aggarwal,
S. Antonelli,
P. Antonioli,
A. Antonov,
M. Arneodo, [......],
L. Zawiejski,
O. Zenaiev,
W. Zeuner,
B. O. Zhautykov,
N. Zhmak,
C. Zhou,
A. Zichichi,
M. Zolko,
D. S. Zotkin,
Z. Zulkapli
[show abstract]
[hide abstract]
ABSTRACT: Single- and double-differential inclusive dijet cross sections in neutral current deep inelastic ep scattering have been measured with the ZEUS detector using an integrated luminosity of 374pb−1. The measurement was performed at large values of the photon virtuality, Q
2, between 125 and 20 000GeV2. The jets were reconstructed with the k
T
cluster algorithm in the Breit reference frame and selected by requiring their transverse energies in the Breit frame, EjetT,BE^{\rm jet}_{T,{\rm B}}, to be larger than 8GeV. In addition, the invariant mass of the dijet system, MjjM_{\rm jj}, was required to be greater than 20GeV. The cross sections are described by the predictions of next-to-leading-order QCD.
European Physical Journal C 04/2012; 70(4):965-982. · 3.63 Impact Factor
-
ZEUS collaboration,
H. Abramowicz,
I. Abt,
L. Adamczyk,
M. Adamus,
R. Aggarwal,
S. Antonelli,
P. Antonioli,
A. Antonov,
M. Arneodo, [......],
L. Zawiejski,
O. Zenaiev,
W. Zeuner,
B. O. Zhautykov,
N. Zhmak,
C. Zhou,
A. Zichichi,
M. Zolko,
D. S. Zotkin,
Z. Zulkapli
[show abstract]
[hide abstract]
ABSTRACT: Charm production in deep inelastic scattering has been measured with the ZEUS detector at HERA using an integrated luminosity
of 120 pb−1. The hadronic decay channels D
+ → K
S
0
π
+, Λ
c
+ → pK
S
0 and Λ
c
+ → Λπ
+, and their charge conjugates, were reconstructed. The presence of a neutral strange hadron in the final state reduces the
combinatorial background and extends the measured sensitivity into the low transverse momentum region. The kinematic range
is 0 < p
T
(D
+, Λ
c
+) < 10 GeV, |η(D
+, Λ
c
+)| < 1.6, 1.5 < Q
2 < 1000 GeV2 and 0.02 < y < 0.7. Inclusive and differential cross sections for the production of D
+ mesons are compared to next-to-leading-order QCD predictions. The fraction of c quarks hadronising into Λ
c
+ baryons is extracted.
KeywordsLepton-Nucleon Scattering
Journal of High Energy Physics 04/2012; 2010(11):1-27. · 5.83 Impact Factor
-
The ZEUS Collaboration,
H. Abramowicz,
I. Abt,
L. Adamczyk,
M. Adamus,
R. Aggarwal,
S. Antonelli,
P. Antonioli,
A. Antonov,
M. Arneodo, [......],
L. Zawiejski,
O. Zenaiev,
W. Zeuner,
B. O. Zhautykov,
N. Zhmak,
C. Zhou,
A. Zichichi,
M. Zolko,
D. S. Zotkin,
Z. Zulkapli
[show abstract]
[hide abstract]
ABSTRACT: The production of beauty quarks in ep interactions has been studied with the ZEUS detector at HERA for exchanged four-momentum squared Q
2>10GeV2, using an integrated luminosity of 363 pb−1. The beauty events were identified using electrons from semileptonic b decays with a transverse momentum 0.9 < pTe < 80.9 < p_{T}^{e} < 8GeV and pseudorapidity |η
e
|<1.5. Cross sections for beauty production were measured and compared with next-to-leading-order QCD calculations. The beauty
contribution to the proton structure function F
2 was extracted from the double-differential cross section as a function of Bjorken-x and Q
2.
European Physical Journal C 04/2012; 71(2):1-15. · 3.63 Impact Factor
-
and ZEUS collaborations,
F. D. Aaron,
H. Abramowicz,
I. Abt,
L. Adamczyk,
M. Adamus,
M. Al-daya Martin,
C. Alexa,
V. Andreev,
S. Antonelli, [......],
Z. Zhang,
B. O. Zhautykov,
A. Zhokin,
C. Zhou,
A. Zichichi,
T. Zimmermann,
H. Zohrabyan,
M. Zolko,
F. Zomer,
D. S. Zotkin
[show abstract]
[hide abstract]
ABSTRACT: A combination is presented of the inclusive deep inelastic cross sections measured by the H1 and ZEUS Collaborations in neutral
and charged current unpolarised e
±
p scattering at HERA during the period 1994-2000. The data span six orders of magnitude in negative four-momentum-transfer
squared, Q
2, and in Bjorken x. The combination method used takes the correlations of systematic uncertainties into account, resulting in an improved accuracy.
The combined data are the sole input in a NLO QCD analysis which determines a new set of parton distributions, HERAPDF1.0,
with small experimental uncertainties. This set includes an estimate of the model and parametrisation uncertainties of the
fit result.
Journal of High Energy Physics 04/2012; 2010(1):1-63. · 5.83 Impact Factor
-
ZEUS collaboration,
H. Abramowicz,
I. Abt,
L. Adamczyk,
M. Adamus,
S. Antonelli,
P. Antonioli,
A. Antonov,
M. Arneodo,
V. Aushev, [......],
R. Yoshida,
C. Youngman,
A. F. Żarnecki,
O. Zenaiev,
B. O. Zhautykov,
N. Zhmak,
C. Zhou,
A. Zichichi,
M. Zolko,
D. S. Zotkin
[show abstract]
[hide abstract]
ABSTRACT: Charged particle production has been studied in neutral current deep inelastic ep scattering with the ZEUS detector at HERA using an integrated luminosity of 0.44 fb−1. Distributions of scaled momenta in the Breit frame are presented for particles in the current fragmentation region. The
evolution of these spectra with the photon virtuality, Q
2, is described in the kinematic region 10 < Q
2 < 41000Ge V2. Next-to-leading-order and modified leading-log-approximation QCD calculations as well as predictions from Monte Carlo models
are compared to the data. The results are also compared to e
+
e
− annihilation data. The dependences of the pseudorapidity distribution of the particles on Q
2 and on the energy in the γp system, W, are presented and interpreted in the context of the hypothesis of limiting fragmentation.
KeywordsLepton-Nucleon Scattering
Journal of High Energy Physics 04/2012; 2010(6):1-42. · 5.83 Impact Factor
-
The and ZEUS collaborations,
F. D. Aaron,
H. Abramowicz,
I. Abt,
L. Adamczyk,
M. Adamus,
M. Aldaya Martin,
C. Alexa,
V. Andreev,
S. Antonelli, [......],
B. O. Zhautykov,
A. Zhokin,
C. Zhou,
A. Zichichi,
T. Zimmermann,
H. Zohrabyan,
M. Zolko,
F. Zomer,
D. S. Zotkin,
R. Zus
[show abstract]
[hide abstract]
ABSTRACT: A search for events containing an isolated electron or muon and missing transverse momentum produced in e
±
p collisions is performed with the H1 and ZEUS detectors at HERA. The data were taken in the period 1994–2007 and correspond
to an integrated luminosity of 0.98 fb−1. The observed event yields are in good overall agreement with the Standard Model prediction, which is dominated by single
W production. In the e
+
p data, at large hadronic transverse momentum P
T
X
> 25GeV, a total of 23 events are observed compared to a prediction of 14.0 ± 1.9. The total single W boson production cross section is measured as 1.06 ± 0.16 (stat.) ± 0.07 (sys.) pb, in agreement with an Standard Model (SM)
expectation of 1.26 ± 0.19 pb.
KeywordsLepton-Nucleon Scattering
Journal of High Energy Physics 04/2012; 2010(3):1-19. · 5.83 Impact Factor
-
The ZEUS Collaboration,
S. Chekanov,
M. Derrick,
S. Magill,
B. Musgrave,
D. Nicholass,
J. Repond,
R. Yoshida,
M. C. K. Mattingly,
P. Antonioli, [......],
W. H. Smith,
H. Wolfe,
S. Bhadra,
C. D. Catterall,
Y. Cui,
G. Hartner,
S. Menary,
U. Noor,
J. Standage,
J. Whyte
[show abstract]
[hide abstract]
ABSTRACT: Measurements of the cross sections for charged current deep inelastic scattering in e
−
p collisions with longitudinally polarised electron beams are presented. The measurements are based on a data sample with an
integrated luminosity of 175 pb−1 collected with the ZEUS detector at HERA at a centre-of-mass energy of 318GeV. The total cross section is given for positively
and negatively polarised electron beams. The differential cross-sections d
σ/dQ
2, d
σ/dx and d
σ/dy are presented for Q
2>200 GeV2. The double-differential cross-section d
2
σ/dxdQ
2 is presented in the kinematic range 280<Q
2<30 000 GeV2 and 0.015<x<0.65. The measured cross sections are compared with the predictions of the Standard Model.
European Physical Journal C 04/2012; 61(2):223-235. · 3.63 Impact Factor
-
ZEUS Collaboration,
S. Chekanov,
M. Derrick,
S. Magill,
B. Musgrave,
D. Nicholass,
J. Repond,
R. Yoshida,
M. C. K. Mattingly,
P. Antonioli, [......],
W. H. Smith,
H. Wolfe,
S. Bhadra,
C. D. Catterall,
Y. Cui,
G. Hartner,
S. Menary,
U. Noor,
J. Standage,
J. Whyte
[show abstract]
[hide abstract]
ABSTRACT: The production of excited charm, D
1(2420)0 and D
2*(2460)0, and charm-strange, D
s1(2536)±, mesons in ep collisions was measured with the ZEUS detector at HERA using an integrated luminosity of 126pb−1. Masses, widths and helicity parameters were determined. The measured yields were converted to the rates of c quarks hadronising as a given excited charm meson and to the ratios of the dominant D
2*(2460)0 and D
s1(2536)± branching fractions. A search for the radially excited charm meson, D
*′(2640)±, was also performed. The results are compared with those measured previously and with theoretical expectations.
European Physical Journal C 04/2012; 60(1):25-45. · 3.63 Impact Factor
-
The ZEUS Collaboration,
S. Chekanov,
M. Derrick,
S. Magill,
B. Musgrave,
D. Nicholass,
J. Repond,
R. Yoshida,
M. C. K. Mattingly,
P. Antonioli, [......],
W. H. Smith,
H. Wolfe,
S. Bhadra,
C. D. Catterall,
Y. Cui,
G. Hartner,
S. Menary,
U. Noor,
J. Standage,
J. Whyte
[show abstract]
[hide abstract]
ABSTRACT: Measurements of the neutral current cross sections for deep inelastic scattering in e
−
p collisions at HERA with a longitudinally polarised electron beam are presented. The single-differential cross-sections d
σ/dQ
2, d
σ/dx and d
σ/dy and the double-differential cross sections in Q
2 and x are measured in the kinematic region y<0.9 and Q
2>185 GeV
2 for both positively and negatively polarised electron beams and for each polarisation state separately. The measurements
are based on an integrated luminosity of 169.9 pb
−1 taken with the ZEUS detector in 2005 and 2006 at a centre-of-mass energy of 318 GeV. The structure functions
x[(F3)\tilde]x\tilde{F_{3}}
and xF
3
γ
Z
are determined by combining the e
−
p results presented in this paper with previously measured e
+
p neutral current data. The asymmetry parameter A
− is used to demonstrate the parity violating effects of electroweak interactions at large spacelike photon virtuality. The
measurements agree well with the predictions of the Standard Model.
European Physical Journal C 04/2012; 62(4):625-658. · 3.63 Impact Factor
-
The ZEUS Collaboration,
S. Chekanov,
M. Derrick,
S. Magill,
B. Musgrave,
D. Nicholass,
J. Repond,
R. Yoshida,
M. C. K. Mattingly,
P. Antonioli, [......],
W. H. Smith,
H. Wolfe,
S. Bhadra,
C. D. Catterall,
Y. Cui,
G. Hartner,
S. Menary,
U. Noor,
J. Standage,
J. Whyte
[show abstract]
[hide abstract]
ABSTRACT: The production of D
±- and D
0-mesons has been measured with the ZEUS detector at HERA using an integrated luminosity of 133.6pb−1. The measurements cover the kinematic range 5<Q
2<1000 GeV2, 0.02<y<0.7, 1.5<p
T
D
<15 GeV and |η
D
|<1.6. Combinatorial background to the D-meson signals is reduced by using the ZEUS microvertex detector to reconstruct displaced secondary vertices. Production cross
sections are compared with the predictions of next-to-leading-order QCD, which is found to describe the data well. Measurements
are extrapolated to the full kinematic phase space in order to obtain the open-charm contribution,
F2c[`(c)]F_{2}^{c\bar{c}}
, to the proton structure function,F
2.
European Physical Journal C 04/2012; 63(2):171-188. · 3.63 Impact Factor
-
The ZEUS Collaboration,
S. Chekanov,
M. Derrick,
S. Magill,
B. Musgrave,
D. Nicholass,
J. Repond,
R. Yoshida,
M. C. K. Mattingly,
P. Antonioli, [......],
W. H. Smith,
H. Wolfe,
S. Bhadra,
C. D. Catterall,
Y. Cui,
G. Hartner,
S. Menary,
U. Noor,
J. Standage,
J. Whyte
[show abstract]
[hide abstract]
ABSTRACT: Subjet distributions were measured in neutral current deep inelastic ep scattering with the ZEUS detector at HERA using an integrated luminosity of 81.7pb−1. Jets were identified using the k
T
cluster algorithm in the laboratory frame. Subjets were defined as jet-like substructures identified by a reapplication of
the cluster algorithm at a smaller value of the resolution parameter ycuty_{\rm cut}. Measurements of subjet distributions for jets with exactly two subjets for ycut=0.05y_{\rm cut}=0.05 are presented as functions of observables sensitive to the pattern of parton radiation and to the colour coherence between
the initial and final states. Perturbative QCD predictions give an adequate description of the data.
European Physical Journal C 04/2012; 63(4):527-548. · 3.63 Impact Factor
-
H. Abramowicz,
I. Abt,
L. Adamczyk,
M. Adamus,
R. Aggarwal,
S. Antonelli,
P. Antonioli,
A. Antonov,
M. Arneodo,
V. Aushev, [......],
L. Zawiejski,
O. Zenaiev,
W. Zeuner,
B. O. Zhautykov,
N. Zhmak,
C. Zhou,
A. Zichichi,
Z. Zolkapli,
M. Zolko,
D. S. Zotkin
[show abstract]
[hide abstract]
ABSTRACT: Three-jet production in deep inelastic ep scattering and photoproduction was investigated with the ZEUS detector at HERA using an integrated luminosity of up to 127 pb-1. Measurements of differential cross sections are presented as functions of angular correlations between the three jets in the final state and the proton-beam direction. These correlations provide a stringent test of perturbative QCD and show sensitivity to the contributions from different color configurations. Fixed-order perturbative calculations assuming the values of the color factors CF, CA, and TF as derived from a variety of gauge groups were compared to the measurements to study the underlying gauge group symmetry. The measured angular correlations in the deep inelastic ep scattering and photoproduction regimes are consistent with the admixture of color configurations as predicted by SU(3) and disfavour other symmetry groups, such as SU(N) in the limit of large N.
Phys. Rev. D. 03/2012; 85(5).
