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Cold nuclear matter effects on J/psi production as constrained by deuteron-gold measurements at root S-NN=200 GeV
Abstract
We present a new analysis of J/ψ production yields in deuteron-gold collisions at √sNN=200 GeV using data taken from the PHENIX experiment in 2003 and previously published in S. S. Adler et al. [Phys. Rev. Lett 96, 012304 (2006)]. The high statistics proton-proton J/ψ data taken in 2005 are used to improve the baseline measurement and thus construct updated cold nuclear matter modification factors (RdAu). A suppression of J/ψ in cold nuclear matter is observed as one goes forward in rapidity (in the deuteron-going direction), corresponding to a region more sensitive to initial-state low-x gluons in the gold nucleus. The measured nuclear modification factors are compared to theoretical calculations of nuclear shadowing to which a J/ψ (or precursor) breakup cross section is added. Breakup cross sections of σbreakup=2.8-1.4+1.7 (2.2-1.5+1.6) mb are obtained by fitting these calculations to the data using two different models of nuclear shadowing. These breakup cross-section values are consistent within large uncertainties with the 4.2±0.5 mb determined at lower collision energies. Projecting this range of cold nuclear matter effects to copper-copper and gold-gold collisions reveals that the current constraints are not sufficient to firmly quantify the additional hot nuclear matter effect.
... However, the suppression of the J/ψ is consistent with nuclear absorption due to collisions with other nucleons inside the Au target. Previous publications have also noted the possibility of nuclear absorption [34][35][36][37][38][39][40], although it is possible that there could be a contribution from comovers as well. [33]. ...
Heavy-ion research at the Relativistic Heavy Ion Collider (RHIC) during the first decade of data collection, approximately during the years 2000–2010, was primarily focused on the study of Au+Au collisions. The search for evidence of quark-gluon plasma (QGP), a state of matter where quarks and gluons become unbound within a high energy density environment, which was at the forefront of research efforts. However, studies of the azimuthal anisotropy parameter v2 in p/d+Pb collisions from the Large Hadron Collider (LHC) yielded results consistent with the hydrodynamic flow, one of the signatures of quark-gluon plasma formation in heavy-ion collisions. Since the publication of these findings, the field of heavy-ion physics has made subsequent measurements in small system collisions to study cold nuclear matter effects as well as look for additional evidence of hot nuclear matter effects. Quarkonia, a bound state of a cc¯ or bb¯ pair, has often been used to probe a wide range of nuclear effects in both large and small collision systems. Here we will review recent quarkonia measurements in small system collisions at RHIC and LHC energies and summarize the experimental conclusions.
... The parameters a = 2b 2 (n − 1), b = Γ( 3 2 )Γ(n − 3 2 )/Γ(n − 1), n = 3.93, and p 2 T p = 3.05 GeV 2 are fitted to match the experimental data for p+p collisions [56,69,70]. The Cronin parameter, which describes the averaged charmonium transverse momentum square obtained from the gluon scattering with a unit of length of nucleons, is set as a gN = 0.1 GeV 2 /fm [41,56] in order to fit experimental data in p-A and lowenergy A-A collisions [71,72]. The mean trajectory length of the two gluons in the two nuclei before the cc formation has been estimated as ρ −1 0 ρ coll (x)/σ inel NN , where ρ 0 is the maximum nuclear density in Eq. (1). ...
The collective properties of final state hadrons produced in the high statistics $_{44}^{96}$Ru+$_{44}^{96}$Ru and $_{40}^{96}$Zr+$_{40}^{96}$Zr collisions at $\sqrt{s_\mathrm{NN}} = 200~\mathrm{GeV}$ are found to be significantly different. Such differences were argued to be precise probes of the difference in nucleon distribution in the isobar nuclei. We investigate the $J/\psi$ production in the isobar collision via a relativistic transport approach. By comparing the isobar systems according to equal centrality bin and equal multiplicity bin, we find that the yield ratio of $J/\psi$ is sensitive to the differences in both the number of binary collisions and the medium evolution. Besides, the elliptic flow $v_2$ of $J/\psi$ is qualitatively different from the light hadrons, and the ratio between Ru+Ru and Zr+Zr collisions is sensitive to the medium evolution. The charmonium production provides an independent probe to study the nucleon distribution in the isobar system.
... To extract the yield, a fit is made which includes the normalized combinatorial background (from above) plus an acceptance- modified [9] double-Gaussian line shape which represents the J /ψ signal, along with an acceptance-modified expo- nential term to account for the remaining correlated physical background. The double-Gaussian line shape is inspired by the line shape measured in p + p collisions [39]; only the yield and the J /ψ mass width are allowed to vary-the latter accounts for its degradation in the large background of heavy-ion collisions. The resultant mass width is found to 064908 Cu+Au Centrality 60-70% ...
We report on J/psi production from asymmetric Cu + Au heavy-ion collisions at root S-NN = 200 GeV at the Relativistic Heavy Ion Collider at both forward (Cu-going direction) and backward (Au-going direction) rapidities. The nuclear modification of J/psi yields in Cu + Au collisions in the Au-going direction is found to be comparable to that inAu + Au collisions when plotted as a function of the number of participating nucleons. In the Cu-going direction, J/psi production shows a stronger suppression. This difference is comparable in magnitude and has the same sign as the difference expected from shadowing effects due to stronger low-x gluon suppression in the larger Au nucleus.
The ALICE experiment was proposed in 1993, to study strongly-interacting matter at extreme energy densities and temperatures. This proposal entailed a comprehensive investigation of nuclear collisions at the LHC. Its physics programme initially focused on the determination of the properties of the quark–gluon plasma (QGP), a deconfined state of quarks and gluons, created in such collisions. The ALICE physics programme has been extended to cover a broader ensemble of observables related to Quantum Chromodynamics (QCD), the theory of strong interactions. The experiment has studied Pb–Pb, Xe–Xe, p–Pb and pp collisions in the multi-TeV centre of mass energy range, during the Run 1–2 data-taking periods at the LHC (2009–2018). The aim of this review is to summarise the key ALICE physics results in this endeavor, and to discuss their implications on the current understanding of the macroscopic and microscopic properties of strongly-interacting matter at the highest temperatures reached in the laboratory. It will review the latest findings on the properties of the QGP created by heavy-ion collisions at LHC energies, and describe the surprising QGP-like effects in pp and p–Pb collisions. Measurements of few-body QCD interactions, and their impact in unraveling the structure of hadrons and hadronic interactions, will be discussed. ALICE results relevant for physics topics outside the realm of QCD will also be touched upon. Finally, prospects for future measurements with the ALICE detector in the context of its planned upgrades will also be briefly described.
The collective properties of final state hadrons produced in the high statistics $$_{44}^{96}$$ 44 96 Ru + $$_{44}^{96}$$ 44 96 Ru and $$_{40}^{96}$$ 40 96 Zr + $$_{40}^{96}$$ 40 96 Zr collisions at $$\sqrt{s_\textrm{NN}} = 200~\textrm{GeV}$$ s NN = 200 GeV are found to be significantly different. Such differences were argued to be precise probes of the difference in nucleon distribution in the isobar nuclei. We investigate the $$J/\psi $$ J / ψ production in the isobar collision via a relativistic transport approach. By comparing the isobar systems according to equal centrality bin and equal multiplicity bin, we find that the yield ratio of $$J/\psi $$ J / ψ is sensitive to the differences in both the number of binary collisions and the medium evolution. Besides, the elliptic flow $$v_2$$ v 2 of $$J/\psi $$ J / ψ is qualitatively different from the light hadrons, and the ratio between Ru + Ru and Zr + Zr collisions is sensitive to the medium evolution. The charmonium production provides an independent probe to study the nucleon distribution in the isobar system.
Transverse momentum integrated and differential J/ψRAA are systematically studied in Au-Au collisions at energies selected for the beam energy scan at the BNL Relativistic Heavy Ion Collider using a transport approach, including cold and hot nuclear effects respectively in the initial conditions and the collision terms. With decreasing energy, while the temperature, lifetime, and size of the quark-gluon plasma (QGP) fireball decrease, the nuclear absorption of the initially produced charmonia is more and more strong, and the nuclear shadowing effect on charmonium regeneration goes to antishadowing first and then to shadowing again. As a competition between the cold and hot nuclear effects, the QGP phase is still important for charmonium production at sNN=200, 62.4, 54,4 and 39 GeV but becomes negligible at sNN=14.5 GeV.
In relativistic heavy ion collisions at RHIC and the LHC, a quark–gluon plasma (QGP) is created for a short duration of about 10 fm/c. Quarkonia (bound states of \(c\bar{c}\) and \(b\bar{b}\)) are sensitive probes of this phase on length scales comparable to the size of the bound states which are less than 1 fm. Observations of quarkonia in these collisions provide us with a lot of information about how the presence of a QGP affects various quarkonium states. This has motivated the development of the theory of heavy quarks and their bound states in a thermal medium, and its application to the phenomenology of quarkonia in heavy ion collisions. We review some of these developments here.
We report measurements of the inclusive J/ψ yield and average transverse momentum as a function of charged-particle pseudorapidity density dNch/dη in p–Pb collisions at sNN=5.02TeV with ALICE at the LHC. The observables are normalised to their corresponding averages in non-single diffractive events. An increase of the normalised J/ψ yield with normalised dNch/dη, measured at mid-rapidity, is observed at mid-rapidity and backward rapidity. At forward rapidity, a saturation of the relative yield is observed for high charged-particle multiplicities. The normalised average transverse momentum at forward and backward rapidities increases with multiplicity at low multiplicities and saturates beyond moderate multiplicities. In addition, the forward-to-backward nuclear modification factor ratio is also reported, showing an increasing suppression of J/ψ production at forward rapidity with respect to backward rapidity for increasing charged-particle multiplicity.
We describe production of heavy quarkonia in pA collisions within the dipole approach, assuming dominance of the perturbative color-singlet mechanism (CSM) in the $p_T$-integrated cross section. Although accounting for a nonzero heavy $Q$-$\bar Q$ separation is a higher twist correction, usually neglected, we found it to be the dominant source of nuclear effects, significantly exceeding the effects of leading twist gluon shadowing and energy loss. Moreover, this contribution turns out to be the most reliably predicted, relying on the precise measurements of the dipole cross section at HERA. The nuclear suppression of quarkonia has been anticipated to become stronger with energy, because the dipole cross section steeply rises. However, the measured nuclear effects remain essentially unchanged within the energy range from RHIC to the LHC. A novel production mechanism is proposed, which enhances the charmonium yield. Nuclear effects for the production of $J/\psi$, $\psi(2S)$, $\Upsilon(1S)$ and $\Upsilon(2S)$ are calculated, in agreement with data from RHIC and LHC. The dipole description offers a unique explanation for the observed significant nuclear suppression of $\psi(2S)$ to $J/\psi$ ratio, related to the nontrivial features of the $\psi(2S)$ wave function.
We report on the measurement of $\rm{J}/\psi$ production in the dielectron channel at mid-rapidity (|y|<1) in p+p and d+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV from the STAR experiment at the Relativistic Heavy Ion Collider. The transverse momentum $p_{T}$ spectra in p+p for $p_{T}$ < 4 GeV/c and d+Au collisions for $p_{T}$ < 3 GeV/c are presented. These measurements extend the STAR coverage for $\rm{J}/\psi$ production in p+p collisions to low $p_{T}$. The $<p_{T}^{2}>$ from the measured $\rm{J}/\psi$ invariant cross section in p+p and d+Au collisions are evaluated and compared to similar measurements at other collision energies. The nuclear modification factor for $\rm{J}/\psi$ is extracted as a function of $p_{T}$ and collision centrality in d+Au and compared to model calculations using the modified nuclear Parton Distribution Function and a final-state $\rm{J}/\psi$ nuclear absorption cross section.
Recent results from the ALICE experiment are presented with a particular emphasis on particle identification, the nuclear modification factor ($R_{AA}$) and azimuthal anisotropy ($v_2$). Comparison of lead-lead and proton-lead results reveals evidence of collectivity in small systems.
We present measurements of J/ψ and ψ (2S) production in proton-lead collisions at a centre of mass energy per nucleon-nucleon interaction of √sNN = 5.02 TeV and in proton- proton collisions at √s = 2.76 TeV, with integrated luminosities of 28.1 nb-1 and 4.0 pb-1, respectively. Both measurements are based on data recorded by the ATLAS detector in 2013 and are performed in the dimuon decay channel. Prompt components of J/ψ and ψ(2S) are separated from the nonprompt components resulting from b-hadron decays through an analysis of the distance between the J/ψ and ψ(2S) decay vertexes and the event primary vertex. The measurements of nuclear modification factors and self-normalized yields for the J/ψ and ψ(2S) are performed in the following ranges: 8.5 < pTµµ < 30 GeV in transverse momentum, -1.5 <y*µµ 1.5 in centre-of-mass rapidity and 0 — 90% in centrality. The differential cross section for production of nonprompt J/ψ is compared to a FONLL calculation which does not include nuclear effects for the ranges of 8 < pTµµ < 30 GeV in transverse momentum, and for |y*| µµ < 1.94 in centre-of-mass rapidity. Forward-backward production ratios are presented and compared to theoretical predictions.
We report on the J/ψ production in Pb-Pb collisions at =2.76 TeV recorded with ALICE during the 2010 and 2011 LHC runs. The J/ψ candidates are reconstructed using the e+e- and μ+μ - decay channels at mid- and forward rapidity, respectively. We show the J/ψ nuclear modification factor RAA as a function of centrality, transverse momentum and rapidity. Our results are compared to the lower energy measurements from PHENIX and to model calculations.
The charmonium transverse momentum distribution is more sensitive to the nature of the hot quantum chromodynamic matter created in high energy nuclear collisions compared with the yield. Taking a detailed transport approach for charmonium motion together with a hydrodynamic description for the medium evolution, the cancellation between the two hot nuclear matter effects, the dissociation and the regeneration, controls the charmonium transverse momentum distribution. In particular, the second moment of the distribution can be used to differentiate between the hot mediums produced at SPS, RHIC and LHC energies.
This contribution highlights recent results from the PHENIX Collaboration at RHIC with emphasis on those obtained through lepton and photon measurements in PHENIX.
Since quarkonia are produced dominantly by gluon-gluon fusion process, it is a good channel to explore the gluon distribution of the nucleon and its modification in nuclei. Contrasting with heavy ion collisions, d + A collisions are not expected to create a hot medium of nuclear matter. Therefore, we can study the quarkonia production in d + A collision and separate the cold nuclear matter effects from the pattern seen in the collisions of large nuclei. The PHENIX collaboration has measured interesting results for J/ψ, ψ' and χc at mid rapidity, |η| < 0.35, and J/ψ and at forward rapidity, 1.2 < η < 2.2 for = 200 GeV d + Au collisions [1–4]. Recently the Forward Silicon Vertex Detector (FVTX) has been installed to the PHENIX detector and much more precise open heavy flavor and vector meson measurements will be possible in the forward rapidity region of the PHENIX Muon Arms. In this talk we will show the aforementioned quarkonia measurements from PHENIX and report on the status of the FVTX detector and physics analyses that will use the FVTX detector in conjunction with the Muon Arms.
In this article we report on the results of quarkonia production in p+p, d+Au, and Au+Au collisions at midrapidity via the dielectron decay channel at √sNN = 200 GeV from STAR. Results from J/ production in p+p collisions for pT <14 GeV/c are presented to provide a baseline for studying suppression in heavy ion collisions and are also used to understand the quarkonium production mechanism. The nuclear modification factor for J/ in d+Au collisions for pT < 5 GeV/c and Au+Au collisions for pT < 10 GeV/c is reported, along with J/π elliptic flow v2 in Au+Au collisions. The results from υ(1S+2S+3S) production in p+p and Au+Au collisions are also provided, and the Upsilon nuclear modification factor in Au+Au collisions is presented.
We calculate open heavy-flavor (HF) production in Au+Au collisions at
$\sqrt{s_{\rm NN}}$=62.4 GeV utilizing a nonperturbative transport approach as
previously applied in nuclear collisions at top RHIC and LHC energies. The
effects of hot QCD matter are treated in a strong-coupling framework, by
implementing heavy-quark diffusion, hadronization and heavy-flavor meson
diffusion within a hydrodynamic background evolution. Since in our approach the
heavy-flavor coupling to the medium is strongest in the pseudo-critical region,
it is of interest to test its consequences at lower collision energies where
the sensitivity to this region should be enhanced relative to the hotter
(early) fireball temperatures reached at top RHIC and LHC energies. We find
that the suppression and flow pattern of the non-photonic electrons from
heavy-flavor decays at 62.4 GeV emerges from an intricate interplay of
thermalization and initial-state effects, in particular a Cronin enhancement
which is known to become more pronounced toward lower collision energies.
We use a Modified DKLMT model (called M-DKLMT model) to study the cold
nuclear matter (CNM) effects on the color singlet J/psi production in d-Au
collisions at RHIC. The cold nuclear effect of dipole-nucleus interactions has
been investigated by introducing a nuclear geometric effect function f({\xi})
to study the nuclear geometry distribution effect in relativistic heavy-ion
collisions. The dependencies of nuclear modification factors (RdA) on rapidity
and centrality are studied and compared to experimental data. It is found that
the M-DKLMT model can well describe the experimental results at both forward-
and mid-rapidity regions in d-Au collisions at RHIC.
The effect of parton energy loss in cold nuclear matter on the suppression of
quarkonia (J/psi, Upsilon) in heavy-ion collisions is investigated, by
extrapolating a model based on coherent radiative energy loss recently shown to
describe successfully J/psi and Upsilon suppression in proton-nucleus
collisions. Model predictions in heavy-ion collisions at RHIC (Au-Au, Cu-Cu,
and Cu-Au) and LHC (Pb-Pb) show a sizable suppression arising from the sole
effect of energy loss in cold matter. This effect should thus be considered in
order to get a reliable baseline for cold nuclear matter effects in quarkonium
suppression in heavy-ion collisions, in view of disentangling hot from cold
nuclear effects.
We review dynamical and thermal models for the collectivity and the suppression pattern of charmed mesons — produced in proton–nucleus and nucleus–nucleus collisions at SPS (~158 A GeV) and RHIC energies (~21 A TeV). In particular, we examine the charmonium "melting" and the "comover dissociation" scenarios — implemented in a microscopic transport approach — in comparison to the available data from the SPS and RHIC. The analysis shows that the dynamics of c and quarks. quarks at RHIC are dominated by partonic or "pre-hadronic" interactions in the strongly coupled plasma stage and can neither be modeled by "hadronic" interactions nor described appropriately by color screening alone. Both the "charmonium melting" and the hadronic "comover absorption and recreation model" are found, however, to be compatible with the experimental observation at SPS energies; the experimental ratio of Ψ′/J/Ψ versus centrality clearly favors the "hadronic comover" scenario. We find that the collective flow of charm in the purely hadronic Hadron-String Dynamics (HSD) transport appears compatible with the data at SPS energies, but the data at top RHIC energies are substantially underestimated. Thus, the large elliptic flow v2 of D-mesons and the low RAA(pT) of J/Ψ seen experimentally have to be attributed to early interactions of non-hadronic degrees of freedom. Simultaneously, we observe that non-hadronic interactions are mandatory in order to describe the narrowing of the J/Ψ rapidity distribution from pp to central Au + Au collisions at the top RHIC energy of . Additionally we demonstrate that the strong quenching of high-pTJ/Ψ's in central Au + Au collisions indicates that a large fraction of final J/Ψ mesons is created by a coalescence mechanism close to the phase boundary. Throughout this review we, furthermore, provide predictions for charm observables from Au + Au collisions at FAIR energies of 25–35 A GeV.
The inclusive J/ψnuclear modification factor (RAA) in Pb–Pb collisions at √sNN=2.76TeVhas been measured by ALICE as a function of centrality in the e+e−decay channel at mid-rapidity (|y| <0.8) and as a function of centrality, transverse momentum and rapidity in the μ+μ−decay channel at forward-rapidity (2.5 <y <4). The J/ψyields measured in Pb–Pb are suppressed compared to those in ppcollisions scaled by the number of binary collisions. The RAAintegrated over a centrality range corresponding to 90% of the inelastic Pb–Pb cross section is 0.72 ±0.06(stat.) ±0.10(syst.)at mid-rapidity and 0.58 ±0.01(stat.) ±0.09(syst.)at forward-rapidity. At low transverse momentum, significantly larger values of RAAare measured at forward-rapidity compared to measurements at lower energy. These features suggest that a contribution to the J/ψyield originates from charm quark (re)combination in the deconfined partonic medium.
This contribution aims at reviewing the experimental measurements of heavy flavours and quarkonia, prior to the new results presented at the Strange Quark Matter 2013 conference.
The measurement of J/ψ azimuthal anisotropy is presented as a function of transverse momentum for different centralities in Au+Au collisions at sqrt[s_{NN}]=200 GeV. The measured J/ψ elliptic flow is consistent with zero within errors for transverse momentum between 2 and 10 GeV/c. Our measurement suggests that J/ψ particles with relatively large transverse momenta are not dominantly produced by coalescence from thermalized charm quarks, when comparing to model calculations.
A review of experimental data on charmoniumproduction that were obtained
in fixed-target experiments at the SPS synchrotron and in proton-proton
collisions and in collisions of lead nuclei in beams of the Large Hadron
Collider (LHC) at CERN (Switzerland) is presented. A comparison with
data obtained at the Brookhaven National Laboratory (USA) from
experiments at the Relativistic Heavy Ion Collider (RHIC) is performed.
Measurement of the suppression of J/ψ-meson production as a possible
signal of the production of quark-gluon plasmawas proposed back in 1986
by T. Matsui and H. Satz. An anomalous suppression of J/ψ-meson
production was discovered by the NA50 Collaboration at SPS (CERN) in
central collisions of lead nuclei at the c.m. collision energy of 158
GeV per nucleon. Data obtained at the c.m. energy of 200 GeV per nucleon
in the PHENIX experiment at RHIC indicate that, depending on
multiplicity, the suppression of J/ψ-meson production at this energy
approximately corresponds to the suppression of J/ψ-meson production
in collisions of lead nuclei at the SPS accelerator. Theoretical models
that take into account the regeneration of J/ψ mesons describe
better RHIC experimental data. The measurement of charmonium production
in proton-proton collisions and in collisions of lead nuclei in LHC
beams revealed the importance of taking into account the regeneration
process. At the LHC energies, it is also necessary to take into account
the contribution of B-meson decays. Future measurements of charmonium
production at the LHC to a higher statistical precision and over an
extended energy region would be of importance for obtaining deeper
insight into the mechanism of charmonium production and for studying the
properties of matter at high energy density and temperature.
Using the two-component model that includes both initial production from
nucleon-nucleon hard scattering and regeneration from produced
quark-gluon plasma (QGP), we have studied the effect of medium
modifications of the binding energies and radii of quarkonia on their
production in heavy-ion collisions. We find that the inclusion of medium
effects is helpful for understanding the observed suppression of
quarkonia production in experiments carried out at the Super Proton
Synchrotron (SPS), the Relativistic Heavy Ion Collider (RHIC), and the
Large Hadron Collider (LHC).
We discuss the gluon saturation/color glass condensate effects on
J/ψ production in high energy pA and AA collisions. We report the
results of numerical calculations of the corresponding nuclear
modification factors. We found a good agreement between our calculations
and the experimental data on J/ψ production in pA collisions. We
also observe that cold nuclear modification effects alone cannot
describe the data on J/ψ production in AA collisions. Our numerical
calculations indicate that the discrepancy arises mostly from the higher
pT's. Additional final state suppression (at RHIC) and
enhancement (at LHC) mechanisms are required to explain the experimental
data.
Using the two-component model that includes both initial production from
nucleon-nucleon hard scattering and regeneration from produced
quark-gluon plasma (QGP), we have studied the effect of medium
modifications of the binding energies and radii of quarkonia on their
production in heavy-ion collisions. We find that the inclusion of medium
effects is helpful for understanding the observed suppression of
quarkonia production in experiments carried out at SPS, RHIC, and LHC.
With the Large Hadron Collider, nuclear collisions have reached the TeV
scale for the first time. This large jump in energy from its
predecessor, the Relativistic Heavy Ion Collider, indicates that a new
discovery regime is open in QCD at high temperatures and densities.
Indeed, the first data are already showing the potential of the LHC to
go far beyond our present knowledge in the field. In particular new
observables, reconstructed jets, are fully available and data have
already been published. These new tools promise to provide an
unprecedented characterization of the properties of the medium produced.
I will review all new opportunities at the LHC in the hard-QCD sector,
especially the case of jets, from a theoretical perspective. I will
comment on the latest developments, the relation of the present data
from RHIC and the LHC, the limitations of the present formalisms and how
these limitations are being overcome.
Transverse momentum distributions of final-state particles produced in soft process in proton-proton (pp) and nucleus-nucleus (AA) collisions at Relativistic Heavy Ion Collider (RHIC) and Large Hadron Collider (LHC) energies are studied by using a multisource thermal model. Each source in the model is treated as a relativistic and quantum ideal gas. Because the quantum effect can be neglected in investigation on the transverse momentum distribution in high energy collisions, we consider only the relativistic effect. The concerned distribution is finally described by the Boltzmann or two-component Boltzmann distribution. Our modeling results are in agreement with available experimental data.
We have developed a hydro+J/ψ model to study the sequential suppression of charmonia at RHIC energy. The (3+1)-dimensional relativistic ideal hydrodynamics is employed to describe the spacetime evolution of hot and dense matter, and charmonia are treated as impurity traversing through the matter. The observed J/ψ suppression at mid-rapidity in Au+Au collisions at RHIC is reproduced well by the sequential melting of χc, ψ' and J/ψ in the medium. The melting temperature of directly produced J/ψ is well determined to be ~2Tc. Azimuthal anisotropy of J/ψ (v2) is calculated with this model. Survival probability and azimuthal anisotropy in the 'hot-wind scenario' are also presented.
Quarkonia were predicted to be suppressed in the 'hot' deconfined matter known as the quark gluon plasma (QGP), but they were also seen to suffer from 'cold' nuclear matter effects (parton shadowing, nuclear absorption, etc.). Both at SPS and RHIC, suppression beyond nuclear effects was observed, but the rapidity dependence of the RHIC result is not easy to interpret. I review here the current status of these results, their possible interpretations and the new measurements that could provide insights on quarkonia suppression. Some of them were presented at this conference.
Using a unified description on multiplicity distributions of final-state particles, the transverse momentum distributions of identified particles produced in proton–proton (pp), proton– and deuteron–nucleus [p(d)A], and nucleus–nucleus (AA) collisions at high energies are studied in this paper. We assume that the transverse momentum distributions of identified particles measured in final state are contributed by a few energy sources which can be regarded as partons or quarks in the interacting system. The particle is contributed by each source with gluons which have transverse momentum distributions in an exponential form. The modelling results are compared and found to be in agreement with the experimental data at high energies.
We have carried out a wide study of shadowing and antishadowing effects on J/ψ production in dAu collisions at
${\sqrt{s_{N N}} = 200}$
GeV. We have studied the effects of three different gluon nPDF sets, using the exact kinematics for a 2 → 2 process, namely g + g → J/ψ + g as expected from LO pQCD. We have computed the rapidity dependence of R
CP and R
dAu for the different centrality classes of the PHENIX data. For mid rapidities, we have also computed the transverse-momentum dependence of the nuclear modification factor, which cannot be predicted with the usual 2 → 1 simplified kinematics. All these observables have been compared to the PHENIX data in dAu collisions.
The PHENIX experiment has measured open heavy-flavor production via
semileptonic decay muons over the transverse momentum range 1 < pT < 6 GeV/c at
forward and backward rapidity (1.4 < |y| < 2.0) in d+Au and p+p collisions at
?sNN = 200 GeV. In central d+Au collisions an enhancement (suppression) of
heavy-flavor muon production is observed at backward (forward) rapidity
relative to the yield in p+p collisions scaled by the number of binary
collisions. Modification of the gluon density distribution in the Au nucleus
contributes in terms of anti-shadowing enhancement and shadowing suppression;
however, the enhancement seen at backward rapidity exceeds expectations from
this effect alone. These results, implying an important role for additional
cold nuclear matter effects, serves as a key baseline for heavy-quark
measurements in A+A collisions and in constraining the magnitude of charmonia
breakup effects at the Relativistic Heavy Ion Collider and the Large Hadron
Collider.
We first determine c and c¯ shower parton distributions in jets induced by light and charm hard partons in the framework of the recombination model from relevant fragmentation functions. The shower parton distributions can be used to calculate other fragmentation functions and study charmed hadron production in other collisions. When the distributions are applied to reproduce the J/ψJ/ψ production in Au+AuAu+Au collisions at sNN=200 GeV, energy loss effect is taken into account for J/ψJ/ψ production due to its momentum loss in traversing the dense medium. We find that the contribution of thermal–shower parton recombination dominates over other mechanisms of hadronization in the region of 3.3<pT<5.8 GeV/c3.3<pT<5.8 GeV/c. The calculated J/ψJ/ψ transverse momentum spectrum is in good agreement with the experimental data.
In the present paper, J/ψJ/ψ production in heavy ion collisions is reviewed. A comparison of the results obtained at SPS and RHIC is discussed and the last results obtained by the PHENIX collaboration on the J/ψv2J/ψv2 measurement are presented in the framework of the regeneration mechanism. Finally, we discuss future measurements at both RHIC and LHC.
Based on a kinetic description of J/psi dissociation and production in an
expanding quark-gluon plasma that is described by a 2+1 dimensional ideal
hydrodynamics, we have studied the hot medium effects on J/psi production in
p+Pb collisions at sqrt{s_{NN}}=5.02 TeV. Including also the cold nuclear
matter effects, we are able to reproduce recent experimental results on the
nuclear modification factor R_{pPb}(J/psi) measured by the ALICE Collaboration.
We have also made predictions for the R_{pPb} of J/psi and the double ratio
R_{pPb}^{pro}(psi')/R_{pPb}^{pro}(J/psi) of prompt quarkonia produced in the
most central 10% p+Pb collisions. We find that different from the cold nuclear
matter effects, the R_{pPb}(J/psi) is slightly smaller than that in the minimum
bias collisions, and the double ratio is significantly less than one at
backward rapidity.
The saturation momentum seen in the nuclear infinite-momentum frame is directly related to transverse momentum broadening of partons propagating through the medium in the nuclear rest frame. Calculation of broadening within the color dipole approach, including the effects of saturation in the nucleus, gives rise to an equation which describes well the data on broadening in the Drell-Yan reaction and heavy quarkonium production.
Yields for J/ψ production in Cu+Cu collisions at sNN=200 GeV have been measured over the rapidity range |y|<2.2 and compared with results in p+p and Au+Au collisions at the same energy. The Cu+Cu data offer greatly improved precision over existing Au+Au data for J/ψ production in collisions with small to intermediate numbers of participants, in the range where the quark-gluon plasma transition threshold is predicted to lie. Cold nuclear matter estimates based on ad hoc fits to d+Au data describe the Cu+Cu data up to Npart∼50, corresponding to a Bjorken energy density of at least 1.5 GeV/fm3.
Charmonia suppression is one of the highly cited signatures of quark–gluon plasma (QGP) formation in relativistic heavy-ion collisions (Matsui and Satz 1986 Phys. Lett.178 416). PHENIX observed a large suppression of J/Ψ production in Au+Au collisions at GeV. This suppression is in fact similar to that observed at lower energies at CERN-SPS and there is currently no theoretical consensus explaining both data sets in terms of cold nuclear matter effects, hot nuclear matter suppression and possible regeneration or coalescence mechanisms. In order to separate these effects the PHENIX collaboration also measured J/Ψ production in d+Au collisions at GeV and Au+Au collisions at low energies ( and 39 GeV) to explore the energy dependence of the suppression in an attempt to disentangle the important contributions to the final yield.
Quarkonia suppression is considered to be one of the key probes of the Quark Gluon Plasma (QGP) created in heavy ion collisions. The PHENIX experiment has measured J/ psi production in a variety of colliding systems. Measurements made in p+p collisions show good agreement with pQCD predictions and serve as baseline for other systems at the same collision energy. The cold nuclear matter contribution to the suppression is constrained through measurements in d+Au collisions. In Au+Au, the suppression observed at mid rapidity is smaller than that at forward rapidity, a tendency opposite to what is expected from the higher gluon density at mid rapidity. The results will be presented and discussed in this article.
The measurement of charmonium suppression in relativistic heavy ion collisions is posited to be an unambiguous probe of the properties of the strongly interacting quark gluon plasma (sQGP). In hot and dense QCD matter Debye color screening prevents charm and anti-charm quark pairs from forming J/ psi mesons if the screening radius is smaller than the binding radius. However, one must have a clear understanding of the expected suppression in normal density QCD matter before interpreting any additional anomalous suppression. The PHENIX experiment has measured J/ psi production from colliding proton + proton and deuteron + gold beams at 200 GeV from the relativistic heavy ion collider (RHIC). The deuteron + gold data can be compared to the proton + proton baseline in order to establish the typical suppression in cold nuclear matter (CNM). For PHENIX, a suppression of J/ psi in cold nuclear matter is observed as one goes forward in rapidity (in the deuteron-going direction), corresponding to a region more sensitive to initial state low- x gluons in the gold nucleus. These results can be convoluted with the nuclear-environment-modified parton distribution functions, extracted from deep inelastic scattering (DIS) and Drell-Yan (DY) data, in order to estimate the J/ psi break up cross section in cold nuclear matter. One can also use a data driven method that does not rely on the assumption of the production mechanism, or PDF parameterization, to extrapolate to the heavy ion collision case. At this time both the predictions for CNM effect suppression in heavy ion collisions are somewhat ambiguous. Future results using the data acquired by the PHENIX experiment in run-6 (p + p) and run-8 (d + Au) will be vital for our understanding. These data, which are in the process of being analyzed, will provide a needed improvement in the statistical and systematic precision of constraints for CNM effects. These constraints must be improved in order to make firm conclusions concerning additional hot nuclear matter charmonium suppression in the sQGP.
By means of a Glauber Monte Carlo framework, the J/ψ production at RHIC energies is studied with the EKS98, EPS09 and HKN07 shadowing parameters. With a χ² analysis of the experimental data given by PHENIX, a significant dependence of the absorption cross-section, σabs, on the J/ψ-nucleon center-of-mass energy, $\sqrt{s_{J/\psi-N}}$, is revealed with the HKN07 shadowing, but an unconspicuous dependence is shown with the EKS98 and EPS09 shadowing. In this paper, the nuclear modification factor Rd Au vs y, pT and Ncoll are also calculated and the theoretical results are in good agreement with the experimental data.
We review the present status in the theoretical and phenomenological understanding of charmonium and bottomonium production in heavy-ion collisions. We start by recapitulating the basic notion of “anomalous quarkonium suppression” in heavy-ion collisions and its recent amendments involving regeneration reactions. We then survey in some detail concepts and ingredients needed for a comprehensive approach to utilize heavy quarkonia as a probe of hot and dense matter. The theoretical discussion encompasses recent lattice QCD computations of quarkonium properties in the Quark–Gluon Plasma, their interpretations using effective potential models, inelastic rate calculations and insights from analyses of electromagnetic plasmas. We illustrate the powerful techniques of thermodynamic Green functions (T-matrices) to provide a general framework for implementing microscopic properties of heavy quarkonia into a kinetic theory of suppression and regeneration reactions. The theoretical concepts are tested in applications to heavy-ion reactions at SPS, RHIC and LHC. We outline perspectives for future experiments on charmonium and bottomonium production in heavy-ion collisions over a large range of energies (FAIR, RHIC-II and LHC). These are expected to provide key insights into hadronic matter under extreme conditions using quarkonium observables.
This document is part of Volume 23 ‘Relativistic Heavy Ion Physics’ of Landolt-Börnstein - Group I ‘Elementary Particles, Nuclei and Atoms’. It contains the Section ‘6.1 Color Deconfinement and Charmonium Production in Nuclear Collisions’ of the Chapter ‘6 Selective Tracer Signals of the QCD Plasma State’ with the content: 6.1 Color Deconfinement and Charmonium Production in Nuclear Collisions 6.1.1 Introduction 6.1.2 Theory 6.1.2.1 Heavy Quarks and Quarkonia 6.1.2.2 Quarkonium Binding and Dissociation 6.1.2.3 Thermal Quarkonium Dissociation 6.1.2.3.1 Interaction Range and Color Screening 6.1.2.3.2 Potential Model Studies 6.1.2.3.3 Charmonium Correlators 6.1.2.4 Charmonium Production in Hadronic Collisions 6.1.2.4.1 Elementary Collisions 6.1.2.4.2 p − A Collisions 6.1.2.4.3 Nuclear Collisions 6.1.2.4.4 Suppression by Comover Collisions 6.1.2.4.5 Suppression by Color Screening 6.1.2.4.6 Enhancement through Regeneration 6.1.2.4.7 Transverse Momentum Behavior 6.1.2.5 Summary of the Theoretical Status 6.1.3 Experiment 6.1.3.1 Charmonium Experiments at the CERN-SPS 6.1.3.1.1 The Nuclear Dependence of Charmonium Production 6.1.3.1.2 Normal Charmonium Production 6.1.3.1.3 The First Hints of an Anomaly in Pb-Pb Collisions 6.1.3.1.4 Anomalous J/ψ Suppression in Pb-Pb Collisions 6.1.3.1.5 J/ψ suppression versus the centrality of the collision 6.1.3.1.6 The transverse momentum dependence of J/ψ 6.1.3.1.7 J/ψ survival pattern: from p-p to Pb-Pb 6.1.3.2 Features of ψ' Suppression at SPS Energies 6.1.3.3 More Results from SPS and RHIC 6.1.3.3.1 J/ψ Suppression in In-In Collisions at 158 GeV 6.1.3.3.2 J/ψ Suppression in A-A Collisions at √s = 200 GeV 6.1.3.4 Discussion and Evaluation 6.1.3.5 Summary of the Experimental Status 6.1.4 Outlook
One observes strong suppression effects for hard probes, e.g. the production of J/ψ or high-p
T
particles, in nucleus–nucleus (AA) collisions at RHIC. Surprisingly, the magnitude of the suppression is quite similar to that at SPS. In order to establish
whether these features arise due to the presence of a thermalized system of quarks and gluons formed in the course of the
collision, one should investigate the impact of suppression mechanisms which do not explicitly involve such a state. We calculate
shadowing for gluons in the Glauber–Gribov theory and propose a model invoking a rapidity-dependent absorptive mechanism motivated
by energy-momentum conservation effects. Furthermore, final-state suppression due to interaction with comoving matter (hadronic
or pre-hadronic) has been shown to describe the data at SPS. We extend this model by including the backward reaction channel,
i.e. recombination of open charm, which is estimated directly from pp data at RHIC. Strong suppression of charmonium both in pA and AA collisions at LHC is predicted. This is in stark contrast with the predictions of models assuming QGP formation and thermalization
of heavy quarks.
We have developed a hydrodynamic model to study sequential melting of charmonium states in an expanding quark–gluon plasma (QGP) medium. According to the initial fluid temperature profile, J/ψ's are randomly distributed in the transverse plane. As the fluid evolves in time, the free streaming J/ψ's are suppressed if the local fluid temperature exceeds a critical temperature. PHENIX data on the centrality dependence of J/ψ suppression in Au+Au collisions at mid-rapidity are explained by sequential melting of the charmonium states, χc, ψ′ and J/ψ, in the expanding medium. The critical temperatures TJ/ψ ≈ 2.09Tc and agree with lattice-motivated calculations. The feed-down fraction F depends on whether the cold nuclear matter effect is included or not. It changes from F = 0.3 with cold nuclear matter effect included to F = 0.5 when the effect is neglected. The model fails to reproduce the PHENIX data on the centrality dependence of J/ψ suppression in Cu+Cu collisions at mid-rapidity, indicating that the mechanism of J/ψ suppression is different in Au+Au and Cu+Cu collisions. We also use the model to predict for the centrality dependence of J/ψ suppression in Pb+Pb collisions at LHC energy, = 5500 GeV. In LHC energy, J/ψ's are more suppressed in mid central collisions than in Au+Au collisions at RHIC energy.
Experimental results have established that very dense partonic matter is formed in Au+Au collisions at RHIC. At such high density, it is believed that quarks and gluons are no longer confined in hadrons, but become constitutes of a quark-gluon plasma (QGP). To understand the properties of the dense matter, it is importnat to measure as many observables as possible and to relate them together to reconstruct the entire time evolution of the system. A large amount of data is now available on low p_T hadrons, high p_T suppression, modificaiton of jet correlation, heavy quarks, J/psi, lepton pairs and direct photons. Recent experimental data from RHIC on these measurements are reviewed.
Interpreting the J/ψ suppression reported in nucleus–nucleus collisions at SPS and RHIC requires a quantitative understanding of cold nuclear-matter effects, such as the inelastic rescattering of J/ψ states in nuclei or the nuclear modification of parton densities. With respect to our former Glauber analysis, we include in the present work the new PHENIX d–Au measurements, and we analyze as well all existing data using the EPS08 nuclear parton densities recently released. The largest suppression reported in the new PHENIX analysis leads in turn to an increase of σ
J/ψN from 3.5±0.3 to 5.4±2.5 mb using the PDF of the proton. The stronger x-dependence of the G
A
/G
p
ratio in EPS08 as compared to e.g. EKS98 shifts the cross section towards larger values at fixed-target energies (x
2∼0.1), while decreasing somehow the value extracted at RHIC (x
2∼10−2).
Yields for J/ψ production in Cu+Cu collisions at sNN=200 GeV have been measured over the rapidity range |y|<2.2 and compared with results in p+p and Au+Au collisions at the same energy. The Cu+Cu data offer greatly improved precision over existing Au+Au data for J/ψ production in collisions with small to intermediate numbers of participants, in the range where the quark-gluon plasma transition threshold is predicted to lie. Cold nuclear matter estimates based on ad hoc fits to d+Au data describe the Cu+Cu data up to Npart∼50, corresponding to a Bjorken energy density of at least 1.5 GeV/fm3.
We report a new measurement of J/ψ, ψ′ and Drell–Yan cross-sections, in the kinematical domain -0.425<ycm<0.575 and -0.5<cosθCS<0.5, performed at the CERN-SPS using 400GeV/c incident protons on Be, Al, Cu, Ag, W and Pb targets. The dependence of the charmonia production cross-sections on the size of the target nucleus allows to quantify the so-called normal nuclear absorption. In the framework of the Glauber model, this new measurement is combined with results previously obtained with the same apparatus, under different experimental conditions, and leads to a precise determination of the J/ψ and ψ′ absorption cross-sections in the surrounding nuclear matter.
The PHENIX experiment at the BNL Relativistic Heavy Ion Collider (RHIC) has measured J/psi production for rapidities -2.2<y<2.2 in Au+Au collisions at square root sNN=200 GeV. The J/psi invariant yield and nuclear modification factor RAA as a function of centrality, transverse momentum, and rapidity are reported. A suppression of J/psi relative to binary collision scaling of proton-proton reaction yields is observed. Models which describe the lower energy J/psi data at the CERN Super Proton Synchrotron invoking only J/psi destruction based on the local medium density predict a significantly larger suppression at RHIC and more suppression at midrapidity than at forward rapidity. Both trends are contradicted by our data.
The field of Diffraction Dissociation, which is the subject of this workshop, began 50 years ago with the analysis of deuteron stripping in low energy collisions with nuclei. We return to the subject in a modern context‐ deuteron dissociation in
s
NN
= 200
GeV
d‐Au collisions recorded during the 2003 RHIC run in the PHENIX experiment. At RHIC energy, d→n+p proceeds predominantly (90%) through Electromagnetic Dissociation and the remaining fraction via the hadronic shadowing described by Glauber. Since the dissociation cross section has a small theoretical error we adopt this process to normalize other cross sections measured in RHIC.
J/{psi} production in d+Au and p+p collisions at {radical}(s{sub NN})=200 GeV has been measured by the PHENIX experiment at rapidities -2.2<y<+2.4. The cross sections and nuclear dependence of J/{psi} production versus rapidity, transverse momentum, and centrality are obtained and compared to lower energy p+A results and to theoretical models. The observed nuclear dependence in d+Au collisions is found to be modest, suggesting that the absorption in the final state is weak and the shadowing of the gluon distributions is small and consistent with Dokshitzer-Gribov-Lipatov-Altarelli-Parisi-based parametrizations that fit deep-inelastic scattering and Drell-Yan data at lower energies.
The PHENIX detector is designed to perform a broad study of A–A, p–A, and p–p collisions to investigate nuclear matter under extreme conditions. A wide variety of probes, sensitive to all timescales, are used to study systematic variations with species and energy as well as to measure the spin structure of the nucleon. Designing for the needs of the heavy-ion and polarized-proton programs has produced a detector with unparalleled capabilities. PHENIX measures electron and muon pairs, photons, and hadrons with excellent energy and momentum resolution. The detector consists of a large number of subsystems that are discussed in other papers in this volume. The overall design parameters of the detector are presented.
We have studied how lepton pairs from decays of heavy-flavoured mesons produced in pA collisions can be used to determine the modifications of the gluon distribution in the nucleus. Since heavy-quark production is dominated by the gg channel, the ratio of correlated lepton pair cross sections from and decays in pA and pp collisions directly reflects the ratio RgA≡fgA/fgp. We have numerically calculated the lepton-pair cross sections from these decays in pp and pA collisions at SPS, RHIC and LHC energies. We find that ratio of the pA to pp cross sections agrees quite well with the input RgA. Thus, sufficiently accurate measurements could be used to determine the nuclear modification of the gluon distribution over a greater range of x and Q2 than presently available, putting strong constraints on models.
In my (“not a summary”) talk at the Hard Probes 2006 conference, I gave “a personal and surely biased view on only a few of the many open questions on quarkonium and electromagnetic probes”. Some of the points reported in that talk are exposed in this paper, having in mind the most important of all the open questions: do we have, today, from experimental data on electromagnetic probes and quarkonium production, convincing evidence that shows, beyond reasonable doubt, the existence of “new physics” in high-energy heavy-ion collisions?
We study the effect of spatially homogeneous and inhomogeneous shadowing on J/psi production in deuterium-nucleus collisions. We discuss how the shadowing and its spatial dependence can be measured by comparing central and peripheral dA collisions. These event classes may be selected by using gray protons from heavy ion breakup and events where the proton or neutron in the deuterium does not interact. We find that inhomogeneous shadowing has a significant effect on central dA collisions, larger than expected in central AA collisions. Results are presented for dAu collisions at sqrt[s(NN)]=200 GeV and dPb collisions at sqrt[s(NN)]=6.2 TeV.
J/psi production in p+p collisions at root s=200 GeV has been measured by the PHENIX experiment at the BNL Relativistic Heavy Ion Collider over a rapidity range of -2.2 < y < 2.2 and a transverse momentum range of 0 < p(T)< 9 GeV/c. The size of the present data set allows a detailed measurement of both the p(T) and the rapidity distributions and is sufficient to constrain production models. The total cross section times the branching ratio is B-ll sigma(J/psi)(pp)=178 +/- 3(stat)+/- 53(sys)+/- 18(norm) nb.
The PHENIX experiment has measured the suppression of semi-inclusive single high transverse momentum pi^0's in Au+Au collisions at sqrt(s_NN) = 200 GeV. The present understanding of this suppression is in terms of energy-loss of the parent (fragmenting) parton in a dense color-charge medium. We have performed a quantitative comparison between various parton energy-loss models and our experimental data. The statistical point-to-point uncorrelated as well as correlated systematic uncertainties are taken into account in the comparison. We detail this methodology and the resulting constraint on the model parameters, such as the initial color-charge density dN^g/dy, the medium transport coefficient <q^hat>, or the initial energy-loss parameter epsilon_0. We find that high transverse momentum pi^0 suppression in Au+Au collisions has sufficient precision to constrain these model dependent parameters at the +/1 20%-25% (one standard deviation) level. These constraints include only the experimental uncertainties, and further studies are needed to compute the corresponding theoretical uncertainties.
This is a review of the theoretical background, experimental techniques, and phenomenology of what is called the "Glauber Model" in relativistic heavy ion physics. This model is used to calculate "geometric" quantities, which are typically expressed as impact parameter (b), number of participating nucleons (N_part) and number of binary nucleon-nucleon collisions (N_coll). A brief history of the original Glauber model is presented, with emphasis on its development into the purely classical, geometric picture that is used for present-day data analyses. Distinctions are made between the "optical limit" and Monte Carlo approaches, which are often used interchangably but have some essential differences in particular contexts. The methods used by the four RHIC experiments are compared and contrasted, although the end results are reassuringly similar for the various geometric observables. Finally, several important RHIC measurements are highlighted that rely on geometric quantities, estimated from Glauber calculations, to draw insight from experimental observables. The status and future of Glauber modeling in the next generation of heavy ion physics studies is briefly discussed.
I present here a new Glauber-inspired approach to derive normal cold nuclear matter effects on $J/\psi$ production in Au-Au collisions. In an as much as possible model-independent way, it extrapolates the centrality dependent yields from d-Au to Au-Au collisions. I then compare to the new Au-Au measurements shown by the PHENIX experiment in this conference. In the most central collisions, $J/\psi$ survival probabilities beyond cold nuclear matter effects are found to be $44\pm23%$ at forward ($y=1.7$) and $25\pm12%$ at mid ($y=0$) rapidities.
We study medium modifications of J/psi production in cold nuclear media in deuterium-nucleus collisions. We discuss several parameterizations of the modifications of the parton densities in the nucleus, known as shadowing, an initial-state effect. We also include absorption of the produced J/psi by nucleons, a final-state effect. Both spatially homogeneous and inhomogeneous shadowing and absorption are considered. We use the number of binary nucleon-nucleon collisions as a centrality measure. Results are presented for d+Au collisions at sqrt{S_{NN}} = 200 GeV and for d+Pb collisions at sqrt{S_{NN}} = 6.2 TeV. To contrast the centrality dependence in pA and dA collisions, we also present pPb results at sqrt{S_{NN}} = 8.8 TeV. Comment: 22 pages, 11 figures, uses revtex
We perform a next to leading order QCD global analysis of nuclear deep inelastic scattering and Drell-Yan data using the convolution approach to parameterize nuclear parton densities. We find both a significant improvement in the agreement with data compared to previous extractions, and substantial differences in the scale dependence of nuclear effects compared to leading order analyses.
In this note we present a study of the radiative tails in the invariant mass spectra of muon or electron pairs from J/psi, psi(2S) and Upsilon(1S) decays which is due to an additional emission of a photon. An analytic formula for dilepton mass spectra in radiative decays is derived and a Monte Carlo simulation for realistic detector conditions is used to study effects on the spectra. A rather simple parameterisation is given, suitable for the treatment of real data.