Round Table Workshop on NICA Physics Dubna,September 9-12,20091 J/Ψ Production in Heavy Ion Collisions J/Ψ Production in Heavy Ion Collisions Pengfei ZHUANG

Round Table Workshop on NICA Physics Dubna,September 9-12,2009 1

J/J/ΨΨ Production in Production in Heavy Ion CollisionsHeavy Ion Collisions

Pengfei ZHUANG Pengfei ZHUANG

Tsinghua University, BeijingTsinghua University, Beijing

IntroductionIntroduction

J/J/ΨΨ at SPS at SPS

J/J/ΨΨ at RHIC at RHIC

J/J/ΨΨ at NICA at NICA


●● produced only in the initial impact, and no extra production in the lproduced only in the initial impact, and no extra production in the later evolutionater evolution a probe of early thermalization and a probe of QGP a probe of early thermalization and a probe of QGP

●●produced via hard processproduced via hard process rrather solid groundather solid ground

importance of heavy quarksimportance of heavy quarks

B.Mueller, nucl-th/0404015B.Mueller, nucl-th/0404015

Matsui and Satz 1986: Matsui and Satz 1986: J/J/ΨΨ suppression as a signature of QGP formation in HI suppression as a signature of QGP formation in HI


● ● both both initial production and regeneration initial production and regeneration ● ● both normal suppression and anomalous suppressionboth normal suppression and anomalous suppression

J/J/ΨΨ motion in heavy ion collision motion in heavy ion collision

hot nuclear matter effectshot nuclear matter effects

cold nuclear matter effectscold nuclear matter effects


J/J/ΨΨ at SPS: normal suppression at SPS: normal suppression

mechanism: multi-scattering between J/mechanism: multi-scattering between J/ΨΨ and spectator nucleons and spectator nucleons R.Vogt, Phys.Rept.310, 197(1999) R.Vogt, Phys.Rept.310, 197(1999) C.Gerschel, J.Hufner, Annu.Rev.Nucl.Part.Sci. 49, 225(1999)C.Gerschel, J.Hufner, Annu.Rev.Nucl.Part.Sci. 49, 225(1999)

6.5 1.0 mbabs conclusion:conclusion: nuclenuclear absorption can well explain the J/ar absorption can well explain the J/ΨΨ yield in p-A and light nuclear col yield in p-A and light nuclear collisions at SPS energy !lisions at SPS energy !

NA38NA38


model 1: Debye screeningmodel 1: Debye screening (Matsui & Satz, 1986) (Matsui & Satz, 1986)

NA38NA38 at T=0at T=0

at Tat T≠ 0≠ 0

J/J/ΨΨ at SPS: anomalous suppression at SPS: anomalous suppression

model 2: threshold model model 2: threshold model (Blaizot, Dinh, Ollitrault, 2000)(Blaizot, Dinh, Ollitrault, 2000)

model 3: comover interaction model 3: comover interaction Capella, Feireiro, Kaidalov, 200Capella, Feireiro, Kaidalov, 2000)0) /J meson D D


J/J/ΨΨ at RHIC: at RHIC: regenerationregeneration

there are about 10 pairs of c quarks in a central Au-Au collision at RHIC energy and more there are about 10 pairs of c quarks in a central Au-Au collision at RHIC energy and more than 100 pairs at LHC energythan 100 pairs at LHC energy important J/important J/ΨΨ regeneration at high energies: regeneration at high energies:in QGP in hadron gasin QGP in hadron gas

the competition between J/\psi suppression and regeneration leads to the question:the competition between J/\psi suppression and regeneration leads to the question: J/ J/ ΨΨ suppression or enhancement at suppression or enhancement at high energies?high energies?

model 1: statistical production at Tc, model 1: statistical production at Tc, no initial production no initial production Andronic, PBM, Redlich, Stachel, 2007 Andronic, PBM, Redlich, Stachel, 2007

mesons/c c J g

model 2: continuous production inside QGP model 2: continuous production inside QGP with anomalous suppression, no initial production with anomalous suppression, no initial production Thews, Mangano, 2006 Thews, Mangano, 2006

model 3: two-component model, initial production + model 3: two-component model, initial production + regeneration regeneration Grandchamp, Rapp, Brown, 2004Grandchamp, Rapp, Brown, 2004

regeneration in hadron gas is important tooregeneration in hadron gas is important too Bratkovs Bratkovskaya, Cassing, Stoecker, 2003 kaya, Cassing, Stoecker, 2003

the competition between suppression the competition between suppression

and regeneration explains well the dataand regeneration explains well the data


J/J/ΨΨ at RHIC: is at RHIC: is regeneration necessary ? I regeneration necessary ? I

J/J/ΨΨ puzzle 1: puzzle 1: almost the same suppression at almost the same suppression at SPS and SPS and RHIC ! RHIC !

Kaczmarek et al., 2003Kaczmarek et al., 2003

explanation without regeneration:explanation without regeneration: Schroedi Schroedinger equation for c cbar with lattice potentinger equation for c cbar with lattice potential gives the charmonium dissociation tempal gives the charmonium dissociation temperature:erature:

Karsch, Kharzeev, Satz, 2006Karsch, Kharzeev, Satz, 2006

if Tif TSPSSPS<< T TRHICRHIC<T<TJ/J/ΨΨ , the suppression at SPS , the suppression at SPS and RHIC will be the same and it explains thand RHIC will be the same and it explains the puzzle 1. it looks not necessary to introde puzzle 1. it looks not necessary to introduce the regeneration .uce the regeneration .

explanation with regeneration: explanation with regeneration: at RHIC, at RHIC, stronger suppression and stronger stronger suppression and stronger regenerationregeneration


J/J/ΨΨ at RHIC: is at RHIC: is regeneration necessary ? II regeneration necessary ? II

J/J/ΨΨ puzzle 2: puzzle 2: strstronger suppression at forward rapidity onger suppression at forward rapidity ! !

explanation with regenerationexplanation with regeneration: : stronger regeneration at mistronger regeneration at mid rapidity d rapidity Liu, Xu, Zhuang, 2009Liu, Xu, Zhuang, 2009

mid-rapiditymid-rapidity forward rapidityforward rapidity

explanation without hot nuclear matter effectsexplanation without hot nuclear matter effects:: different J/different J/ΨΨ produ production in pA and AA from pp ction in pA and AA from pp Kharzeev, Levin, NaKharzeev, Levin, Na

rdi, Tuchin, 2009rdi, Tuchin, 2009

strong J/Ψ suppression even at T=0 !


transport model transport model (Hufner, Zhuang, 2003; Zhu, Xu, Zhuang, 2005): (Hufner, Zhuang, 2003; Zhu, Xu, Zhuang, 2005): transport equation for Jtransport equation for JΨΨ and hydrodynamics for QGP and hydrodynamics for QGP

for J/for J/ΨΨ yield, almost all the models – with and without the assumption of Q yield, almost all the models – with and without the assumption of QGP and with and without regeneration mechanism – describe the observeGP and with and without regeneration mechanism – describe the observed suppression, after at least one parameter is adjusted.d suppression, after at least one parameter is adjusted.

the transverse momentum distribution which depends more directly on ththe transverse momentum distribution which depends more directly on the production and suppression mechanisms contains more information on e production and suppression mechanisms contains more information on the nature of the medium and J/the nature of the medium and J/ΨΨ and may help to distinguish between dif and may help to distinguish between different scenarios.ferent scenarios.

J/J/ΨΨ at SPS: at SPS: transverse momentum transverse momentum

suppression regeneration

no regeneration at SPSno regeneration at SPS

very important leakage effect !very important leakage effect !

pt enhancement at SPSpt enhancement at SPS


J/J/ΨΨ at RHIC: at RHIC: transverse momentumtransverse momentum

Yan, Xu, Zhuang, 2006; LiYan, Xu, Zhuang, 2006; Liu, Xu, Zhuang, 2009u, Xu, Zhuang, 2009

low pt is controlled by both initial production low pt is controlled by both initial production and regenerationand regeneration

high pt enhancement is induced by Cronin high pt enhancement is induced by Cronin effect in initial production effect in initial production

initial production + regeneration explain initial production + regeneration explain both the yield and transverse momentum both the yield and transverse momentum distributiondistribution

pt broadeningpt broadening

pt suppressionpt suppression

strong strong pt suppressionpt suppression


● ● LHC: almost only regeneration, sensitive to hot nuclear matterLHC: almost only regeneration, sensitive to hot nuclear matter RHIC:RHIC: both initial production and regeneration both initial production and regeneration

the calculation needs a quite accurate fine-tuning between the calculation needs a quite accurate fine-tuning between the two production mechanismsthe two production mechanisms

SPS:SPS: almost only initial productionalmost only initial production NICA: only initial production, sensitive to cold nuclear matterNICA: only initial production, sensitive to cold nuclear matter

J/J/ΨΨ at NICA: cold nuclear matter effects at NICA: cold nuclear matter effects

● ● is the rapidity dependence at NICA similar to that at RHIC? is the rapidity dependence at NICA similar to that at RHIC? 2 gluon fusion mechanism: no2 gluon fusion mechanism: no 3 gluon fusion mechanism: yes 3 gluon fusion mechanism: yes (Kharzeev et al., 2009)(Kharzeev et al., 2009)

the rapidity dependence can distinguish from the initial production the rapidity dependence can distinguish from the initial production mechanismsmechanisms

● ● normal vs anomalous suppression at NICA normal vs anomalous suppression at NICA longer collision time (~1 fm), important (dominant) nuclear absorption,longer collision time (~1 fm), important (dominant) nuclear absorption, shorter life time of hot matter, weaker anomalous suppressionshorter life time of hot matter, weaker anomalous suppression


● ● pt distribution at NICApt distribution at NICA LHC: strong pt suppression due to thermalized regenerationLHC: strong pt suppression due to thermalized regeneration

NICA: strong pt enhancement due to Cronin effect ( gluon multi NICA: strong pt enhancement due to Cronin effect ( gluon multi scattering ) and leakage effect ( high momentum particles can scattering ) and leakage effect ( high momentum particles can escape the hot medium ).escape the hot medium ). the life time of hot matter is short at NICA but long at RHIC and the life time of hot matter is short at NICA but long at RHIC and

LHC, the leakage effect is therefore more important at NICA. LHC, the leakage effect is therefore more important at NICA.

J/J/ΨΨ at NICA: others at NICA: others

● ● mixed phase at NICA mixed phase at NICA the phase transition at NICA may be of first order the phase transition at NICA may be of first order life time of mixed phase fraction of anomalous suppression life time of mixed phase fraction of anomalous suppression RHIC 4.5 fm 7% RHIC 4.5 fm 7%SPS 5 fm 30%SPS 5 fm 30%

long life time of mixed phase and short life time of quark matter long life time of mixed phase and short life time of quark matter the suppression in the mixed phase becomes more the suppression in the mixed phase becomes more important at NICA !important at NICA !


conclusionconclusion

cold and hot nuclear mater effects on J/cold and hot nuclear mater effects on J/ΨΨ in high energy nu in high energy nuclear collisions are still not clearclear collisions are still not clear

at NICA:at NICA:

1)1) Transverse momentum and rapidity distributions can distinTransverse momentum and rapidity distributions can distinguish from J/guish from J/ΨΨ production mechanisms: production mechanisms: * pt enhancement due to Cronin effect and strong leaka* pt enhancement due to Cronin effect and strong leakage effect ge effect * stronger suppression at forward rapidity (3 gluon fusio * stronger suppression at forward rapidity (3 gluon fusion) or at mid rapidity (2 gluon fusion)?n) or at mid rapidity (2 gluon fusion)?

2) Nuclear absorption dominates the J/2) Nuclear absorption dominates the J/ΨΨ suppression and ansuppression and anomalous suppression happens mainly in the mixed phaseomalous suppression happens mainly in the mixed phase

3) non-thermalized J/3) non-thermalized J/ΨΨ has small (zero) elliptic flow. has small (zero) elliptic flow.


thanks for your attentionthanks for your attention


centrality dependence at SPScentrality dependence at SPS

Zhu, Zhuang, PRC67, 067901(2003)Zhu, Zhuang, PRC67, 067901(2003)

J/psi R_AA and <p_t^2> at SPS energy as functions of cenJ/psi R_AA and <p_t^2> at SPS energy as functions of centrality and p_t can be well described by nuclear and meditrality and p_t can be well described by nuclear and medium absorption, without regeneration. um absorption, without regeneration.


dominant regeneration at LHCdominant regeneration at LHC

while initial production and regeneration are equally important at RHIC, the J/psi yield while initial production and regeneration are equally important at RHIC, the J/psi yield at LHC is characterized by the regeneration only!at LHC is characterized by the regeneration only!

* J/psi is controlled by reg* J/psi is controlled by regeneration eneration * J/psi yield at LHC incr * J/psi yield at LHC increases with centralityeases with centrality

Liu, Xu, Zhuang, Liu, Xu, Zhuang, PLB, 2009 and QM20 PLB, 2009 and QM200909


initial production & nuclear absorption are included in initial conditioninitial production & nuclear absorption are included in initial condition

)),,(),,((10

22BtBAtAgNpptt zbxTzxTnapp


near side correlation in sQGPnear side correlation in sQGPDD

we take drag coefficient to we take drag coefficient to be a parameter charactering be a parameter charactering the coupling strength the coupling strength

* c quark motion in QGP:* c quark motion in QGP:

* QGP evolution: * QGP evolution: ideal hydrodynamicsideal hydrodynamics

for strongly interacting quark-gluon plasma: for strongly interacting quark-gluon plasma: ● ● at RHIC, the back-to-back correlation is washed out.at RHIC, the back-to-back correlation is washed out.● ● at LHC, c quarks are fast thermalized, the strong float LHC, c quarks are fast thermalized, the strong flow push the D and Dbar to the near side!w push the D and Dbar to the near side!

Zhu, Xu, Zhuang, PRL100, 152301(2008)Zhu, Xu, Zhuang, PRL100, 152301(2008)

large drag parameter is confirmed by R_AA and v_2 of large drag parameter is confirmed by R_AA and v_2 of non-photonic electrons non-photonic electrons (PHENEX, 200(PHENEX, 2007; Moore and Teaney, 2005; Horowitz, Gyulassy, 2007).7; Moore and Teaney, 2005; Horowitz, Gyulassy, 2007).

Documents

Round Table Workshop on NICA Physics Dubna,September 9-12,20091 J/Ψ Production in Heavy Ion Collisions J/Ψ Production in Heavy Ion Collisions Pengfei ZHUANG