<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>J</mml:mi><mml:mo>/</mml:mo><mml:mi>Ψ</mml:mi></mml:math>suppression in colliding nuclei: Statistical model analysis

Prorok, Dariusz; Turko, L.

doi:10.1103/physrevc.64.044903

Cited by 7 publications

(26 citation statements)

References 45 publications

(91 reference statements)

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“…A thermalized system of this kind would stay in equilibrium until Γ falls below the expansion rate and the heavy-quark system freezes out. This resembles models of statistical hadronization [23]. However, unlike those, we do not force the heavy-quarkonia to freeze out at the same temperature as particles made with lighter quarks.…”

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confidence: 99%

Thermalization of quarkonia at energies available at the CERN Large Hadron Collider

Gupta

Sharma

2014

Phys. Rev. C

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We argue that the relative yields of Υ states observed at the LHC can be understood as bottomonium states coming to early thermal equilibrium and then freezing out. The bottomonium freezeout temperature is approximately 250 MeV. We examine its systematics as a function of centrality. We remark on the interesting differences seen by the CMS and ALICE experiments in the charmonium sector.PACS numbers: 12.38. Mh, 11.15.Ha, 12.38.Gc A thermal medium can disrupt the formation of a bound state of a heavy quark, Q and antiquark,Q [1]. This is a multi-scale problem, involving the temperature T and the quark mass M . The quark is heavy, i.e., M/T ≫ 1. For the charmonium this ratio is about 5-10 and for the bottomonium it is around 15-30; so both these flavours can be considered to be heavy in this sense. Also, M/Λ ≫ 1, where Λ ≃ m ρ /2 is the typical scale of QCD [27]. This second comparison implies that in theQQ bound state the quarks are slow, with velocity v 2 ≃ 0.23 for charm and v 2 ≃ 0.08 for bottom [2]. In NRQCD counting, the binding energy B ≃ M v 2 ≃ Λ in both cases [3]. For the temperature range of relevance, we find that B/T ≃ Λ/T ≃ 1. As a result, thermal effects can drastically modify the bound state.Since a thermal medium can be formed in PbPb collisions, but not in pp collisions, there should be certain systematic differences between the yields in these two cases [4]. Such effects were first seen at the SPS [5], but there were important backgrounds to the signal which came from the initial state via parton density effects [6] and the final state through comover interactions [7]. Furthermore, the observed effects switched on slowly with centrality and nuclear size, and so were difficult to interpret clearly [8].At the LHC the experimental situation has changed drastically. Initial state effects cannot be the explanation, since the relevant values of the Bjorken variable are almost equal for the three bottomonium states, and a different common value for the two charmonium states, implying that parton density effects would be the same. Final state comover interactions were invoked even at the LHC in order to explain the observed suppression of J/ψ [13]. The comoving material which is thermalized gives rise to the signal. The comovers responsible for the background are unthermalized and relatively cold spectators from the initial PbPb collision. However, the data are taken at central rapidity and separated from the spectator fragments by ∆y ≃ 6. So comover interactions cannot be the explanation for the observations. In this cleaner environment it would be interesting to check whether the data allow a thermal interpretation.We begin by noting that the equilibrium density of heavy quarkonia, with massis small. As a result, the mean distance between quarkonia in thermal equilibrium, λ, is large. In fact, we find that T λ = z −1/3 T /M exp(2M/3T ). For z = 1 this dimensionless number is over 100 for charmonia and over 10 million for bottomonia. So, for both the charm and bottom systems, the exponential dominate...

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mentioning

confidence: 99%

Thermalization of quarkonia at energies available at the CERN Large Hadron Collider

Gupta

Sharma

2014

Phys. Rev. C

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“…For the higher temperatures all curves excluding the pion case behave qualitatively in the same way. From T ≈ 70 MeV they decrease to their minima (for n B = 0.65 fm −3 at T ∼ = 219.6 MeV, for n B = 0.25 fm −3 at T ∼ = 202.5 Left panel: Energy density in units of T 4 versus scaled temperature T /T c for the present hadron resonance gas model [5] compared with the QCD Lattice data [22] and the Hagedorn resonance gas with scaled hadron masses to adapt for the case of unphysical quark masses in the Lattice simulation [23]. Right panel: Dependence of the sound velocity squared on temperature for n B = 0.65 fm −3 (short-dashed), n B = 0.25 fm −3 (dashed), n B = 0.05 fm −3 (solid) and n B = 0 (long-dashed).…”

Section: The Sound Velocity In the Mchgmentioning

confidence: 99%

“…(10), (13) and (15) but with g(p T , ǫ 0 ), σ J/ψN and M changed appropriately (for details see [5]). …”

Section: J/ψ Absorption In the Expanding Mchgmentioning

confidence: 99%

“…Then, the transverse expansion starts as a rarefaction wave moving inward S ef f at t 0 . From the considerations based on the relativistic kinetic equation (for details see [5,10]), the survival fraction of J/Ψ in the hadron gas as a function of the initial energy density ǫ 0 in the CRR is obtained:…”

Section: J/ψ Absorption In the Expanding Mchgmentioning

confidence: 99%

“…(10) and (13) include parts which depend on the impact parameter b and the left hand sides are functions of ǫ 0 only, the expression converting the first quantity to the second (or reverse) should be defined. This is done with the use of the dependence of ǫ 0 on the transverse energy E T extracted from NA50 data [2] (for details see [5]). To make the model as realistic as possible, one should keep in mind that only about 60% of the observed J/Ψ's are directly produced during the collision.…”

Section: J/ψ Absorption In the Expanding Mchgmentioning

confidence: 99%

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J∕ψ absorption in a multicomponent hadron gas

Prorok¹,

Turko²,

Blaschke³

et al. 2008

AIP Conference Proceedings

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Abstract.A model for anomalous J/Ψ suppression in high energy heavy ion collisions is presented. As the additional suppression mechanism beyond standard nuclear absorption inelastic J/Ψ scattering with hadronic matter is considered. Hadronic matter is modeled as an evolving multi-component gas of point-like non-interacting particles (MCHG). Estimates for the sound velocity of the MCHG are given and the equation of state is compared with Lattice QCD data in the vicinity of the deconfinement phase transition. The approximate cooling pattern caused by longitudinal expansion is presented. It is shown that under these conditions the resulting J/Ψ suppression pattern agrees well with NA38 and NA50 data.

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Charmonium suppression at RHIC and SPS: A hadronic baseline

2010

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A kinetic equation approach is applied to model anomalous J/ψ suppression at RHIC and SPS by absorption in a hadron resonance gas which successfully describes statistical hadron production in both experiments. The puzzling rapidity dependence of the PHENIX data is reproduced as a geometric effect due to a longer absorption path for J/ψ production at forward rapidity.Keywords: J/ψ suppression, heavy-ion collisions, hadron gas PACS: 14.40.Gx, 24.10.Pa, 25.75.-q IntroductionThe effect of J/ψ suppression [1] is one of the diagnostic tools to prove quark-gluon plasma (QGP) formation in heavy-ion collisions. After a rich phenomenology provided by the CERN-SPS experiments NA3, NA38, NA50 and NA60, which nevertheless could not unambiguously prove QGP formation, the situation became even more complex due to first results from RHIC experiments PHENIX and STAR. New experiments are planned at CERN-LHC and FAIR-CBM, for a recent review, see [2]. In order to make progress in the interpretation of experimental findings it is important to define benchmarks, such as a baseline from a statistical kinetic model provided in this communication, which is based on a purely hadronic description.Measurements of J/ψ suppression in Au-Au and Cu-Cu collisions by STAR and PHENIX experiments [3,4,5] brought up two unexpected re-

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J/Ψsuppression in colliding nuclei: Statistical model analysis

Cited by 7 publications

References 45 publications

Thermalization of quarkonia at energies available at the CERN Large Hadron Collider

Thermalization of quarkonia at energies available at the CERN Large Hadron Collider

J∕ψ absorption in a multicomponent hadron gas

Charmonium suppression at RHIC and SPS: A hadronic baseline

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