STAR Regional Meeting, Weihai, July, 2012STAR Regional Meeting, Weihai, July, 2012

J/J/ΨΨ TMD as a Sensitive Signature of QGP TMD as a Sensitive Signature of QGP Pengfei Zhuang (Tsinghua University, Beijing)Pengfei Zhuang (Tsinghua University, Beijing)

●● The J/The J/ψψ Puzzle Puzzle

● ● A Full Transport Approach A Full Transport Approach ● ● Running Dissociation Temperature Running Dissociation Temperature ●● Summary and OutlookSummary and Outlook

Collaborated with Dr. Nu Xu and Yunpeng Liu, Kai Zhou, and Xianglei ZhuCollaborated with Dr. Nu Xu and Yunpeng Liu, Kai Zhou, and Xianglei Zhu

62 GeV

J/J/ψψ Puzzle Puzzle

Result: Result: the yields at SPS, RHIC and the yields at SPS, RHIC and LHC have similar trend. LHC have similar trend. Question: Question: is J/ is J/ψψ still a sensitive still a sensitive signature of the QGP ?signature of the QGP ?

Result: Result: the yields at SPS, RHIC and the yields at SPS, RHIC and LHC have similar trend. LHC have similar trend. Question: Question: is J/ is J/ψψ still a sensitive still a sensitive signature of the QGP ?signature of the QGP ?

Transverse Momentum DistributionTransverse Momentum Distribution

Pt distribution is sensitive to the dynamics of the system Pt distribution is sensitive to the dynamics of the system and should tell us more about the nature of the medium ! and should tell us more about the nature of the medium !

Data and Our Model PredictionData and Our Model Prediction

+ equation of state + equation of state

A Full Transport Approach for Quarkonia in HICA Full Transport Approach for Quarkonia in HIC

● ● quarkoniumquarkonium transport equations transport equations

● ● initial production , including CNM. initial production , including CNM.

● ● QGPQGP hydrodynamics hydrodynamics

αα: suppression : suppression ββ: regeneration: regeneration

● ● analytic solution analytic solution

0, 0T n

Yunpeng Liu, Nu Xu, Kai Zhou, Xianglei Zhu, PZ, 2005-2012Yunpeng Liu, Nu Xu, Kai Zhou, Xianglei Zhu, PZ, 2005-2012

40( , , )f p x t

to study the J/to study the J/ψψ interaction with QGP, we need a interaction with QGP, we need a dynamic description for both J/dynamic description for both J/ψψ and QGP ! and QGP !

Dissociation Cross Section Dissociation Cross Section

( ) / J g Q Q

( , )gp p●● gluon dissociation cross section calculated by OPE gluon dissociation cross section calculated by OPE (Bhanot, Peskin,1999):(Bhanot, Peskin,1999):

●● at finite temperature, we use the classical relationat finite temperature, we use the classical relation2

2

( )( , , ) ( , )

(0)g g

r Tp p T p p

r is calculated through the is calculated through the

Schroedinger equationSchroedinger equation

2 ( )r T

●● regeneration rate is determined by the detailed balanceregeneration rate is determined by the detailed balance

●● J/J/ΨΨ dissociation rate dissociation rate

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Charm Quark DistributionCharm Quark Distribution

Due to interaction with the medium, charm quarks become soft in the Due to interaction with the medium, charm quarks become soft in the medium, and therefore the regeneration happens only in the low pt region. medium, and therefore the regeneration happens only in the low pt region.

From observed D-meson flow at RHIC, charm quarks seem to be thermalized, From observed D-meson flow at RHIC, charm quarks seem to be thermalized, we take thermal distribution for charm quarks in the medium. we take thermal distribution for charm quarks in the medium.

Initial fraction and regeneration fraction for J/Initial fraction and regeneration fraction for J/ΨΨ produced in central Pb+Pb produced in central Pb+Pb collisions at LHC energy, with thermal charm quark distribution.collisions at LHC energy, with thermal charm quark distribution.

Prediction at RHIC (1) Prediction at RHIC (1)

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Prediction at RHIC (2)Prediction at RHIC (2)

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Prediction at LHC (1)Prediction at LHC (1)

the talks by Kai Zhou and Baoyi Chen this evening

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Prediction at LHC (2)Prediction at LHC (2)

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Prediction at LHC (3)Prediction at LHC (3)

It is sensitive to the hot nuclear matter effect (thermalization It is sensitive to the hot nuclear matter effect (thermalization of charm quarks and regeneration in QGP), of charm quarks and regeneration in QGP), but it is almost but it is almost independent of the cold nuclear matter effect (shadowing) !independent of the cold nuclear matter effect (shadowing) !

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Moving Heavy Quark PotentialMoving Heavy Quark Potential

lattice calculated free energy for static heavy quarks

J/J/ψψs are not at rest in the QGP!s are not at rest in the QGP!what is the potential for moving what is the potential for moving heavy quarks ?heavy quarks ?

The screening effect is due to the rearrangement of the The screening effect is due to the rearrangement of the charged particles when a pair of heavy quarks (source) is charged particles when a pair of heavy quarks (source) is put into the medium. put into the medium. When the source moves in the medium, it costs some time When the source moves in the medium, it costs some time for the screening charges to catch up with the source. This for the screening charges to catch up with the source. This delay of response reduces the screening charges around the delay of response reduces the screening charges around the source and thus weakens the screening effect.source and thus weakens the screening effect.

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Running Dissociation Temperature Running Dissociation Temperature

color conductivity from lattice simulation color conductivity from lattice simulation

A non-equilibrium problem, the transport equation for the A non-equilibrium problem, the transport equation for the time dependent charge density , time dependent charge density ,

relaxation time relaxation time

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R_AA at High PtR_AA at High Pt

It seems no way to reach the large R_AA at high Pt, It seems no way to reach the large R_AA at high Pt, if the dissociation temperature does not run!if the dissociation temperature does not run!

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While the quarkonium yield behaves While the quarkonium yield behaves similarly at SPS, RHIC and LHC, the similarly at SPS, RHIC and LHC, the transverse momentum distribution is transverse momentum distribution is sensitive to the nature of the medium sensitive to the nature of the medium and can be used to signal the QGP and can be used to signal the QGP formation. formation.

ConclusionConclusion