zebo tang (for the star collaboration) university of science and technology of china (ustc)
DESCRIPTION
J/ y production and correlation in p+p and Au+Au collisions at STAR. Zebo Tang (for the STAR Collaboration) University of Science and Technology of China (USTC). Motivation. J/ y production in p+p collisions: Baseline for A+A - PowerPoint PPT PresentationTRANSCRIPT
QM2011 1Zebo Tang, USTC
Zebo Tang (for the STAR Collaboration)University of Science and Technology of China (USTC)
J/ production and correlation in p+p and Au+Au collisions at STAR
QM2011 2Zebo Tang, USTC
Motivation
J/ production in A+A collisions:• J/ only known probe to test deconfinement• Color screening in deconfined medium• Charm quark coalescence/recombination• Formation time effect at high-pT
Experimental measurements in different centralities:• Spectra and radial flow• Nuclear modification factor• Elliptic flow
J/ production in p+p collisions:• Baseline for A+A • Provide insight in production mechanism (Color-singlet vs. Color-octet)• Establish/Estimate feeddown Experimental measurements:• J/ spectra• J/-hadron correlation
QM2011 3Zebo Tang, USTC
Previous measurements at STAR
STAR, PRC80, 041902(R), 2009
Spectra harder than CSMLeave no room for feeddown in COM
First J/-hadron correlation in p+p at RHICFirst estimation of BJ/ feeddown
No suppression at high-pT in Cu+Cu collisions
QM2011 4Zebo Tang, USTC
STAR detector2 coverage at mid-rapidity (||<1)
TPC+BEMC+(MRPC-TOF)+(HLT) in this analysis
QM2011 5Zebo Tang, USTC
High-pT J/ signals
p+p, 2009
TPC+BEMC for spectraTPC+BEMC+TOF for correlation
TPC+BEMC+TOF
Significantly reduced material in 2009 p+p and 2010 Au+Au collisions Clear signal in both p+p and Au+Au collisionsHigh Signal/Background ratio in p+p allows correlation study
QM2011 6Zebo Tang, USTC
J/ spectra in 200GeV p+p collisionsConsistent with previous results
Good agreement between STAR and PHENIX
Color singlet model: direct NNLO still misses the high-pT part P. Artoisenet et al., Phys. Rev. Lett. 101, 152001 (2008),
and J.P. Lansberg private communication.
LO CS+CO: leave no room for feeddown at high pTG. C. Nayak, M. X. Liu, and F. Cooper, Phys. Rev. D68, 034003 (2003), and private communication.
Tsallis Blast-Wave model: ZBT et al., arXiv:1101.1912; JPG 37, 085104 (2010)
PHENIX: Phys. Rev. D 82, 012001 (2010)STAR: Phys. Rev. C80, 041902(R) (2009)
CEM can reasonably explain the spectra
PRC80, 041902(R), 2009
PLB370, 239, 1996PLB200, 380, 1988
PRD71, 032001, 2005EPJC71, 1575, 2011
QM2011 7Zebo Tang, USTC
(BJ/ / (inclusive J/
• Extracted from near side J/-h correlation• Consistent with previous results• No significant beam energy dependence• Can be used to constrain B production
Ramona Vogt
Workshop on Heavy Quark Production in Heavy-ion Collisions, Jan. 6, 2011, Purdue University
Based on decay kinematics etc in PYTHIA
QM2011 8Zebo Tang, USTC
Away side associated hadron pT spectra
Consistent with hadron-hadron correlation away-side seems to come from gluon/light quark fragmentation
STAR, PRL95, 152301 (2005)
QM2011 9Zebo Tang, USTC
J/ spectra in 200GeV Au+Au collisionsGood agreement between STAR and PHENIX
Significantly extend the pT range to 10 GeV/c
J/ spectra significantly softer than the prediction from light hadrons Much smaller radial flow? Regeneration at low pT?
Tsallis Blast-Wave model: ZBT et al., arXiv:1101.1912; JPG 37, 085104 (2010)
Phys. Rev. Lett. 98, 232301 (2007)
QM2011 10Zebo Tang, USTC
RAA vs. pT
Increase from low pT to high pT
Consistent with unity at high pT in (semi-) peripheral collisionsMore suppression in central than in peripheral even at high pT
STAR CuCu: PRC80, 014922(R)PHENIX: PRL98, 232301
Yunpeng Liu, Zhen Qu, Nu Xu and Pengfei Zhuang, PLB 678:72 (2009) and private comminication Xingbo Zhao and Ralf Rapp, PRC 82,064905(2010) and private communication
QM2011 11Zebo Tang, USTC
RAA vs. Npart
Systematically higher at high pT in all centralitiesSuppression in central collisions at high pT
System size dependent due to J/ formation time effect?Escaping at high pT (without jet quenching effect)?
Yunpeng Liu, Zhen Qu, Nu Xu and Pengfei Zhuang, PLB 678:72 (2009) and private comminication Xingbo Zhao and Ralf Rapp, PRC 82,064905(2010) and private communication
STAR Pion: Yichun Xu at QM2009
QM2011 12Zebo Tang, USTC
J/ elliptic flow v2
Poster session 2, board# 60, Hao Qiu (for the STAR Collaboration)
STAR Preliminary
Consistent with zeroDisfavor coalescence from thermalized charm quarks
[1] V. Greco, C.M. Ko, R. Rapp, PLB 595, 202.[2] L. Ravagli, R. Rapp, PLB 655, 126.[3] L. Yan, P. Zhuang, N. Xu, PRL 97, 232301.[4] X. Zhao, R. Rapp, 24th WWND, 2008.[5] Y. Liu, N. Xu, P. Zhuang, Nucl. Phy. A, 834, 317.[6] U. Heinz, C. Shen, priviate communication.
MB
7.8fm
7.8fm
MB
20-40%
20-60%7.8fm
QM2011 13Zebo Tang, USTC
Summary In p+p collisions
J/ spectra measurements are extended to high pT
Large S/B ratio allows correlation study B has sizeable (not dominant) contribution at high pT
High-pT J/ away side hadron production consistent with gluon / light quark fragmentation
In heavy-ion collisions Observation of no suppression for J/ at high pT (5-10 GeV/c) at STAR in 200GeV Cu+Cu and peripheral Au+Au collisions, And suppression at high pT in central Au+Au collisions J/ suppression at high pT less than that at low pT J/ v2 measurements are consistent with zero, disfavor coalescence from thermalized charm quarks J/ spectra and v2 are consistent with J/ not participating in bulk flow
QM2011 14Zebo Tang, USTC
82±136
J/ in Au+Au @ BES
Clear signals seen in both 39 GeV and 62 GeV Au+Au collisionsReference data available from Fermi Lab Experiments and ISR
62 GeV Au+AuEMC Trigger
39 GeV Au+AuEMC Trigger
39 GeV Au+AuMin. Bias Trigger
Thank you!
QM2011 15Zebo Tang, USTC
backup
QM2011 16Zebo Tang, USTC
Sequential dissociation?
Npart/2
• J/ spectra are modified in medium in Au+Au collisions• Spectra does not support scenario of large radial flow• RAA of high-pT J/ and Upsilon similar (poster: Rosi Reed for STAR)• J/ v2 consistent with zero, calescence from thermalized charm quarks unlikely