夸克胶子等离子体中 J/ Ψ 的压低和重产生 J/ Ψ Suppression and Regeneration in Quark-Gluon Plasma

Pengfei ZHUANG Quark Matter 2006, Shanghai, China, Nov. 14 – 20, 2006 1

夸克胶子等离子体中夸克胶子等离子体中 J/J/ΨΨ的的压压低和重低和重产产生生 J/J/ΨΨ Suppression and Regeneration in Quark-Gluon Suppression and Regeneration in Quark-Gluon

PlasmaPlasmaPengfei ZHUANG ( 庄鹏飞 ) Tsinghua University, Beijing ( 清华大学，北京 )

1. 1. 引言引言 Motivation and Our Idea Motivation and Our Idea 2. 2. 论证论证 J/J/ΨΨ Transport in QGP Transport in QGP 3. 3. 结果结果 Comparison Comparison with RHIC Data with RHIC Data 4. 4. 总结总结 SummarySummarywith Li YAN ( 严力 ), Xianglei ZHU( 朱相雷 ) of Tsinghua and Nu XU ( 许怒 ) of

LBNL nucl-th/0608010 (PRL, accepted) PLB607,107(2005)


1. Motivation1. Motivation

J/J/ suppression: suppression: proposed as a smoking gun for detecting QGP (Matsui and Satz)

At SPS:At SPS: initial production, almost no regeneration, nuclear absorption and suppression in

QGP or hadron gas (many works) At At RHIC and LHC:RHIC and LHC: regeneration (Thews, Braun-Munzinger, Stachel, ,… )

supported by lattice calculation of spectral function (Karsch,

Hatsuda, …) Some Models:Some Models: statistic production at hadronization (Braun-Munzinger, Stachel, Gorenstein, Kostyuk, Stoecker, Greiner,

Grandchamp, Rapp,…), coalescence at hadronization (Greco, Ko, Rapp,…), kinetic formation inside QGP (Thews, Mangano, Grandchamp, Rapp, Brown, Polleri, Renk,

Schneider, Weise, …)

Questions:Questions: what iswhat is the ratio of regenerated to initially produced J/ the ratio of regenerated to initially produced J/ s ?s ? how to differentiate J/ how to differentiate J/ψψ regeneration regeneration mechanisms ?mechanisms ?


our treatmentour treatment

● both initial production and continuous regeneration in QGP

● suppression and regeneration via gluon dissociation and the inverse process

● transport equation for J/Ψ + hydrodynamic equation for QGP

● two limits for charm quark distribution: no interaction limit and thermalization limit

1. Motivation1. Motivation

0


● initial condition:

: continuous regeneration in QGP: suppression in QGP

c

2. J/2. J/ΨΨ Transport in QGP Transport in QGP

● transverse transport equation with loss and gain terms in central rapidity region:

p_t broadening due to Cronin effect

distribution function: assumption: 40% of final state J/Ψs is from the feed-down of

● analytic solution

first term: initial production, second term: continuous regeneration,

both suffer suppression in QGP


2. J/2. J/ΨΨ Transport in QGP Transport in QGP● loss and gain terms via gluon dissociation

thermal gluon distribution controlled by hydrodynamics

● two limits of charm quark distribution: weak interaction limit,

strong interaction limit,

● suppression and regeneration in hadron gas are neglected, since the hadron density is much lower than the gluon density

perturbative calculation with nonrelativistic Coulomb potential (Peskin, Bhanot …)

pQCD distribution (Thews,…)nuclear geometry

thermal distribution controlled by hydrodynamics

via detailed balance


● 1+2 dimensional ideal hydrodynamics of QGP

● EoS (Sollfrank,…) ideal QGP phase: u, d, s (150 MeV) quarks and gluons, ideal hadron phase: hadrons and resonances with mass up to 2 GeV, a first order deconfinement phase transition

● Initial condition:

are determined by (Kolb, Heinz, Rapp,…)

● Parameters at RHIC energy

2. J/2. J/ΨΨ Transport in QGP Transport in QGP

in thermal distributions


3. Comparison with RHIC Data3. Comparison with RHIC Data

initial production and regeneration are equally important in central collisions, initial production dominates the yield in semi-central collisions, not sensitive to the charm quark distribution. see also Rapp, Grandchamp, Brown, 2004, 2005

we can not describe the flat structure at in present calculation.

PHENIX data nucl-ex/0611020

hep-ex/0611020

● yield


regeneration is definitely important in central collisions, thermal scenario looks better to fit the data.

● transverse momentum


PHENIX data nucl-ex/0611020

hep-ex/0611020


0 1 2 3 4 5-2

0

2

4

6

8

10

12

14

16

18 whole temp range T=230MeV T=200MeV T=185MeV T=175MeV

V2(%

)

Pt(GeV)

1) initial V2 is small, V2 at SPS is really very small, see Gianluca Usai, this conference 2) regenerated V2 is large 3) total V2 is small due to dominance of initial production

*V2 can differentiate initial production from regeneration, V2 can differentiate initial production from regeneration, *V2 can answer the question if charm quarks are thermalized, V2 can answer the question if charm quarks are thermalized, *V2 can differentiate sudden from continuous regeneration V2 can differentiate sudden from continuous regeneration

● V2 at b=7.8 fm



● ratio of regenerated to initially produced J/Ψ’s at LHC

initially produced charmoniums are all eaten up by QGP, the regeneration dominates the charmonium behavior at any centrality,

at LHC are all controlled by the regeneration

● V2 can differentiate sudden regeneration from continuous regenerationV2 can differentiate sudden regeneration from continuous regeneration



● a J/Ψ transport equation with both initial production and continuous regeneration

● transverse momentum distributions, especially V2, are sensitive to

the production mechanisms at RHIC: ● significant regeneration in central collisions ● still important initial production in non-central collisions ● V2

can differentiate initial production from regeneration at LHC: ● initially produced J/Ψare eaten up by QGP, and any J/Ψ behavior is

dominated by the regeneration. ● V2 can differentiate sudden from continuous regeneration

4. Summary4. Summary

We thank R.Rapp. H.Stocker, R.Thews and R.Vogt for helpful discussions


Selected Topics on Heavy Flavor Productionin High-Energy Collision

Physics Department, Tsinghua University, Beijing, China

November 22 - 23, 2006

Local organizers:Nu Xu (Lawrence Berkeley National Laboratory)Pengfei Zhuang (Tsinghua University)

Topics: Open Heavy Flavor in High Energy Collisions Heavy Quarkonia in Medium Thermalization

http://qm.phys.tsinghua.edu.cn/thu-henp/hf/


5. Charm Quark Thermalazation5. Charm Quark Thermalazation

Question: Are charm quarks thermalized in QGP? Question: Are charm quarks thermalized in QGP? Idea: D mesons should be sensitive to the thermalazationIdea: D mesons should be sensitive to the thermalazation

● charm quark transport in QGP

mean field effect, neglecting inelastic interaction,

relaxation time approximation for elastic interaction

● analytic solution

● initial pQCD distribution



● thermal parameters in relaxation time approximation

energy and momentum conservation in collisions

● D meson production via coalescence on hadronization hypersurfaces

transport distribution at hadronization hydrodynamic distribution at hadronization

Ko,…


● charm quark pt distribution at b=7.2 fm in Au+Au


means complete thermalization, more low pt charm quarks in thermalization distribution



● charm quark V2 at b=7.2 fm in Au+Au

V2 at pt > 1 GeV is very sensitive to if charm quarks are thermalized.V2 at pt > 1 GeV is very sensitive to if charm quarks are thermalized.

numerical calculation on D meson is not yet finished.

Documents

夸克胶子等离子体中 J/ Ψ 的 压 低和重 产 生 J/ Ψ Suppression and Regeneration in Quark-Gluon Plasma

夸克胶子等离子体中 J/ Ψ 的压低和重产生 J/ Ψ Suppression and Regeneration in Quark-Gluon Plasma