Download - Identified particle transverse momentum distributions in 200 GeV Au+Au collisions at RHIC
Haidong Liu (USTC) 2
Main contribution Identified charged hadron spectra
PRL 97 (2006) 152301 (cited by 61 articles )
nucl-ex 0606003 (cited by 26 articles)
Light nuclei spectra and v2 J. Phys. G: Nucl. Part Phys. 34(2007) S1087-s1091 (cited by
3 articles ) International Journal of Modern Physics E , Vol: 16 Issue:
10 (2007) Page: 3280 - 3285 Anti-baryon phase space density study
nucl-ex/0610035 Submitted to PLB
Haidong Liu (USTC) 4
Heavy-ion collisions at RHIC
Time
initial state
pre-equilibrium(high Q2 interactions)
QGP andhydrodynamic expansion
hadronization
freeze-out
Physics: 1) Parton distributions in nuclei 2) Initial conditions of the collision 3) A new state of matter – Quark-Gluon Plasma and its properties 4) Hadronization and freeze-out
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Particles production
Charged hadron (pions and protons) production Low pT – hydrodynamic Intermediate pT – partonic
coalescence High pT – jet fragmentation
Haidong Liu (USTC) 6
pQCD: Color charge and flavor dependence of parton energy loss
dE/dx(c/b)<dE/dx(uds)< dE/dx(g)
S. Wicks et al., NPA 784(2007)426
Haidong Liu (USTC) 7
X.N. Wang: PRC58(2321)1998.
Study the PID spectra and pbar/p ratios can help to further understand how the g/q jets interact with the medium
Parton energy loss in HIJING
HIJING calculation
Haidong Liu (USTC) 8
Different mechanisms govern hadron formation in the different kinematic region
Different hadron species may have different sources
Those sources (g/q) may have different behavior when propagating the medium
To study those behaviors,PID in large pT range is required!
Haidong Liu (USTC) 9
STAR detectors: TPC & TOFr
A new technology (TOF) ----Multi-gap Resistive Plate Chamber
1. Good timing resolution (<100ps)2. Two trays (TOFr+TOFp) for run 4,
acceptance~0.01, 120 trays (TOFr) in the future
Time Projection Chamber
1. Tracking2. Ionization energy loss (dE/dx)
Haidong Liu (USTC) 10
PID – Hadrons
TPC
Relativistic rising of dE/dx
High pT
High performance of time resolution
Low & intermediate pT2.5<pT<3.0
PID up to 12 GeV/c
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Pion & proton spectra
PID up to 12 GeV/c
STAR Collaboration PRL 97 (2006) 152301PAs: H. Liu, O. Barannikova, L. Ruan and Z. Xu
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Nuclear Modification factor
In central Au+Au collisions:
At 1.5<pT<7 GeV/c, RCP(p+pbar) > RCP() , RCP(p+pbar) shows obvious decreasing trend.
At 4<pT<12 GeV/c, both and p are strongly suppressed. They approach to each other at about 0.3
Curve:I. Vitev, PLB 639 (2006) 38.pT
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Color charge and flavor dependence of parton energy loss
High pT Rcp measurements: , p(pbar), e, , 0
pT
Nucl-ex/0607012 PRL 96 (2006) 202301
Rcp(RAA)~0.2 for all these particles!
Haidong Liu (USTC) 14
Anti-particle to particle ratios
1. -/+ are consistent with flat at unity in all pT, no significant centrality dependence.
2. pbar/p ratio: no significant centrality dependence, parton energy loss underpredicts the ratios (X.N. Wang, PRC 58 (2321) 1998).
Haidong Liu (USTC) 15
Proton over pion ratios
1. The p(pbar)/ ratios in Au+Au collisions show strong centrality dependence.
2. In central Au+Au collisions, the p(pbar)/ ratios reach maximum value at pT~2-3 GeV/c, approach the corresponding ratios in p+p, d+Au collisions at pT>5 GeV/c.
3. In general, parton energy loss models underpredict p/ ratios. R.J. Fries, et al., Phys. Rev. Lett. 90 202303 (2003); R. C. Hwa, et al., Phys. Rev. C 70, 024905 (2004); DELPHI Collaboration, Eur. Phy. J. C 5, 585 (1998), Eur. Phy. J. C 17, 207 (2000).
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B/M enhancement at intermediate pT
1) The relative baryon enhancement is clearly observed in the p/pi ratios at
intermediate pT, the similar behavior can also be seen in the /Ks0
ratios. At the same pT region, the NQ scaling of v2 has also been observed. This can
be explained by the parton coalescence phenomena.2) In general, parton energy loss models underpredict p/ ratios. R.J. Fries, et al., Phys. Rev. Lett. 90 202303 (2003); R. C. Hwa, et al., Phys. Rev. C 70, 024905 (2004); DELPHI Collaboration, Eur. Phy. J. C 5, 585 (1998), Eur. Phy. J. C 17, 207 (2000).
STAR Nucl-ex/0601042
Haidong Liu (USTC) 17
Summary
First time to extend PID pt range up to 12 GeV/c for charged pion, kaon and (anti-)proton
First time to observe the similar suppressions for high pt mesons and baryons, which challenges the standard parton energy loss model
Further test the coalescence model in the intermediate pt range