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J/ Ψ TMD as a Sensitive Signature of QGP Pengfei Zhuang (Tsinghua University, Beijing) ● The J/ ψ Puzzle ● A Full Transport Approach ● Running Dissociation Temperature ● Summary and Outlook
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J/Ψ TMD as a Sensitive Signature of QGP Pengfei Zhuang (Tsinghua University, Beijing) ● The J/ψ Puzzle ● A Full Transport Approach ● Running Dissociation Temperature ● Summary and Outlook Collaborated with Dr. Nu Xu and Yunpeng Liu, Kai Zhou, and Xianglei Zhu STAR Regional Meeting, Weihai, July, 2012
J/ψ Puzzle Result: the yields at SPS, RHIC and LHC have similar trend. Question: is J/ψ still a sensitive signature of the QGP ? • 62 GeV
Transverse Momentum Distribution Pt distribution is sensitive to the dynamics of the system and should tell us more about the nature of the medium ! Data and Our Model Prediction
A Full Transport Approach for Quarkonia in HIC Yunpeng Liu, Nu Xu, Kai Zhou, Xianglei Zhu, PZ, 2005-2012 to study the J/ψ interaction with QGP, we need a dynamic description for both J/ψ and QGP ! ● QGPhydrodynamics + equation of state ● quarkoniumtransport equations α: suppression β: regeneration ● analytic solution ● initial production , including CNM.
Dissociation Cross Section ●gluon dissociation cross section calculated by OPE (Bhanot, Peskin,1999): ●at finite temperature, we use the classical relation is calculated through the Schroedinger equation ● J/Ψdissociation rate ●regeneration rate is determined by the detailed balance
Charm Quark Distribution Due to interaction with the medium, charm quarks become soft in the 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, we take thermal distribution for charm quarks in the medium. Initial fraction and regeneration fraction for J/Ψ produced in central Pb+Pb collisions at LHC energy, with thermal charm quark distribution.
Prediction at LHC (1) the talks by Kai Zhou and Baoyi Chen this evening
Prediction at LHC (3) It is sensitive to the hot nuclear matter effect (thermalization of charm quarks and regeneration in QGP), but it is almost independent of the cold nuclear matter effect (shadowing) !
Moving Heavy Quark Potential lattice calculated free energy for static heavy quarks J/ψs are not at rest in the QGP! what is the potential for moving heavy quarks ? The screening effect is due to the rearrangement of the charged particles when a pair of heavy quarks (source) is put into the medium. When the source moves in the medium, it costs some time for the screening charges to catch up with the source. This delay of response reduces the screening charges around the source and thus weakens the screening effect.
Running Dissociation Temperature A non-equilibrium problem, the transport equation for the time dependent charge density , relaxation time color conductivity from lattice simulation
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!
Conclusion While the quarkonium yield behaves similarly at SPS, RHIC and LHC, the transverse momentum distribution is sensitive to the nature of the medium and can be used to signal the QGP formation. 15