马余刚On behalf of China-STAR Group

Shanghai Institute of Applied Physics (SINAP)Central China Normal University, Wuhan (CCNU)

University of Science and Technology of China (USTC) Tsinghua University (TU)

Institute of Modern Physics, Lanzhou (IMP) Institute of High Energy Physics, Beijing (IHEP)

Shandong University (SDU)

十三届全国中高能核物理大会暨第七届全国中高能核物理专题研讨会

合肥， 11 月 5-7 号， 2009

RHIC-STAR 中国组物理研究进展

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报告内容

About STAR-China group & previous physics results based on the TOF trays and STAR detectors;

Recent progress: Discovery of anti-hypertriton V2 scaling & violation, thermalization Strangeness Heavy flavor and Eloss Energy scan and critical point search Longitudinal spin transferSummary & Outlook

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What have we learned? STAR NPA 757 (2005) 102 Strongly interacting, hot, dense matter with partonic collectivityWhat do we do next? Investigate the medium properties: - thermalization degree / EoS

- search for chiral symmetry restoration Search for QCD critical point and phase boundary …

N. Xu

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The STAR Detector - 2 Coverage at Midrapidity

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Typical PID for TPC-alone and TOF alone

TPC alone PID range: pi/k ~0.6 GeV/c,

(pi,k)/p ~1.6GeV/c;

TOF “alone” PID range: pi/k ~1.6GeV/c,

(pi,k)/p ~ 3.0GeV/cm2 m2

TOF=110ps k

p

TPC alone TOF “alone”

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Scope of joint effort supported by NNSFC, CAS and MoST: Six institutions in China are collaborating on the STAR physics program, and on the construction of a 23,000 channel multi-gap resistive plate chamber Time of Flight barrel for STAR

STARSTAR

University of Science and Technology of China (USTC)Tsinghua University Shanghai Institute of Applied Physics (SINAP)Central China Normal University (CCNU)Institute of Modern Physics (IMP)Institute of High Energy Physics (IHEP)

Group Leaders for China-TOF project:

Yu-Gang Ma (SINAP); Hong-Fang Chen (USTC); Jian-Ping Cheng (Tsinghua)

Project Scope: $4.7M from US $2.3M from China (in-kind)

STAR TOF MRPC modules: production completed in China on schedule!所有 MRPC 探测器都已在 STAR 上安装，可以马上采集相关数据！！

1/2 3/4 5/6 7/8 11/129/10 1/2 3/4 5/6 7/8 11/129/10 1/2 3/4 5/6 7/8

2006 2007 2008

Prod Start

132 MRPCs

768 MRPCs

1856 MRPCs

2944 MRPCs

4032 MRPCs

Plan(Finished)

MRPC mass production

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作为 STAR 主要作者已发表的代表性论文 Open Charm Yields in d +Au Collisions at sNN p 200 GeV, Phys. Rev. Lett. 94, 062301 (2005) Identified baryon and meson distributions at large transverse momenta from Au+Au collisions at sqrt(sNN)=200 , Phys.

Rev. Lett. 97, 152301 (2006) Partonic flow and -meson production in Au+Au collisions at √sNN = 200 GeV ， Phys. Rev. Lett. 99 (2007) 112301 Pion, kaon, proton and anti-proton transverse momentum distributions from p +p and d +Au collisions at √sNN = 200

GeV, Phys. Lett. B 616 (2005) 8 Energy and system size dependence of meson production in Cu+Cu and Au+Au collisions, Phys. Lett. B 673 (2009) 183 Spin alignment of K*0(892) and phi(1020) mesons in Au+Au and p+p collisions at sqrt(s_NN) = 200 GeV, Phys. Rev. C 77

(2008) 061902 (R) Mass, quark-number, and √sNN dependence of the second and fourth flow harmonics in ultrarelativistic nucleus-nucleus

collisions ， Phys. Rev. C 75 (2007) 054906 Centrality dependence of charged hadron and strange hadron elliptic flow from √sNN = 200 GeV Au+Au collisions, Phys.

Rev. C 77, 054901 (2008) Measurements of phi meson production in relativistic heavy ion collisions at RHIC, Phys. Rev. C 79, 064903 (2009) J/ψ production at high transverse momenta in p + p and Cu + Cu collisions at √sNN = 200 GeV, Phys. Rev. C 80, 041902(R)

(2009)

Distinguished PhD Students:

中国合作组有许多优秀的学生，例如： 付菁华（华中）， 2005 年度“全国百篇优秀博士论文”奖； 马国亮（上海应物所） , 张一飞 ( 中科大 ) 获得了 2006,2007 年度“中国科学院院长奖学金优秀奖”； 陈金辉（上海应物所） 2008 年度“中国科学院院长奖学金优秀奖”和“ 2009 年中科院 50 篇优秀博士论文”。 朱相雷（清华）， 2008 年度“全国百篇优秀博士论文”奖 李娜（华中师大）， 2009 “Gertrude Scharff-Goldhaber Prize”

董忻（中科大 -LBNL ）， 2005 年度“中国科学院院长奖学金特别奖”；阮丽娟（ ustc-BNL),Goldhaber fellow

。。。。。。

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The 1st ever-observation of an antihypernucleus: 70 ± 17 ;

The consistent check from hypertriton analysis from the same data set supports the signal: 157 ± 30.

J. H. Chen (SINAP), Z.B. Xu (BNL), refer to Z.Xu’s talk, submitted to Science.

The antihypernucleus observation

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3-D nucleus chart

Extend the 3-D chart of nuclides into the anti-matter sector with strangeness degree of freedom.

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S.S. Shi, IOPP, paper under discussion

System size and energy dependence of PID elliptic flow

STAR: preliminary

v2 measurement from Cu + Cu collisions

Glauber eccentricity Similar in the case of CGC eccentricity

NCQ scaling– De-confinement at RHIC– Partonic collectivity

Stronger collective flow in larger system

x

y

x

y

z

x

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At low pT, hydrodynamic mass ordering; At intermediate pT, B/M grouping behavior; Hadrons with u-, d-, s-quarks show similar collectivity

Final word on partonic collectivity at RHIC!S.S. Shi, IOPP, paper under discussion ；

J. H. Chen et al., PRL 99 (2007) 112301

Partonic collectivity

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Breaking of NCQ scaling at high pT

NCQ scaling works at (mT-m)/nq < 1.0 GeV/c2: coalescence region;

A divergence at (mT-m)/nq > 1.0 GeV/c2: hard process becomes to dominate? N. Li, IOPP, paper in prepare

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Ideal hydro fails to reproduce the data. Fluctuation of v2 ,4 plays dominant role! partial thermalization play a slight role ? Viscosity ?

Ideal hydro limit ?

Borghini & Ollitrault, PLB 642 227 (2006)

Ideal hydro: P. Huovinen, private communication

S.S. Shi and N. Li, IOPP

Gombeaud & Ollitrault, 0910.0392

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Centrality Dependence

Au+Au and Cu+Cu at 200 GeV:NcQ scaling for each centrality bin => partonic collectivityCollectivity: Driven by number of participants, NOT by eccentricity.

Larger v2/part indicates stronger flow in more central collisions. Right: The system created in collisions at RHIC is not fully thermalized.

STAR: preliminary

STAR Au + Au 200 GeV : PRC77, 054901 (2008)

S. Voloshin, A. Poskanzer, PL B474, 27(00).D. Teaney, et. al., nucl-th/0110037

STAR preliminary

Hydro limit

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STAR preliminary STAR preliminary

Collapses of proton v1 ?

First measurement of antiproton direct flow;

Collapses of proton v1

Kaon, less shadowing due to the smaller X-section; Negative v1 slope for Kaon, consistent with the ‘anti-flow’ pictureJ. Y. Chen, IOPP, paper in preparation; see her talk this afternoon!

Anti-flow/3rd flow component, with QGP v1 flat at middle rapidity.

Brachmann, Soff, Dumitru, et. al. , PRC 61 (2000) 024909.L.P. Csernai, D. Roehrich ,PLB 458, 454 (1999). M.Bleicher and H.Stocker, PLB 526,309(2002).

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The bulk strangeness production & nuclear modification factor in d+Au

The strangeness enhancement from central d+Au lies in a trend with peripheral Cu+Cu and Au+Au X. Zhu, Tsinghua U.

•K0 agree with charged K at low pT,Λ agrees with proton at intermediate pT (2 – 4GeV/c).• Particle type (baryon/meson) dependence of

RdAu for pT from 2 to 4 GeV/c;

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Extend Kaon measurement up to 15 GeV

STAR preliminary

Charged and neutral kaons are extended up to 15 GeV/c in p+p collisions

The data can provide constraint for pQCD calculation

Y. Xu, USTC, paper under discussion

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pT (GeV/c)

STAR preliminary

RAA(proton)>RAA(pion) at high pT

Which is in contrast to the prediction of color charge dependence of Energy Loss.

how the gluon jet/quark jet interact with the medium created in Au+Au collisions.

RAA(K) ~ 0.4 at high pT > 5.0 GeV/c

consistent with the prediction of jet conversion by interaction with the medium in Au+Au.

RAA() ~ RAA() at high pT: ;

Not a mass effect

Understand energy loss

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Heavy flavor measurement

F. Jin, SINAP; Z.B. Tang, USTC

Non-photonic electron spectra from a low material run (ToF run8)

J/Psi measurement in p+p and Cu+Cu collisions

J/Psi

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Heavy flavor energy loss

Z.B. Tang, USTC, Phys. Rev. C 80 (2009) 041902 (R)

No suppression of J/Psi RAA at higher Pt, contrast to open charm measurement.

No significant near side J/Psi-hadron azimuthal angle correlation, data show low B contribution: (13 5) % .

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The Energy scan program: fluctuation

Particle fluctuation is a possible signal for QCD critical point:

interesting evolution of K/p fluctuations from lowest SPS energies to RHIC energy;

non-monotonic dependence of K/p fluctuation signal.

J. Tian, SINAP, paper in preparation

•No strong non-monotonic dependence with √sNN observed. • The data may provide constraint on the location of QGP phase: μB > 200 MeV • The future RHIC beam energy scan program will provide data of μB 100 - 550 MeV

X.F. Luo, USTC, paper in preparation

Net proton kurtosis analysisK/p fluctuation

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Onset of deconfinement: hypertriton vs.√sNN

Baryon-strangeness correlation via hypernuclei: a viable experimental signal to search for the onset of deconfinement.

S. Zhang, SINAP : arXiv:0908.3357

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Longitudinal spin transfer to

The longitudinal spin transfer is sensitive to the polarized parton distribution and polarized fragmentation functions, has been measured:

The present results don’t provide conclusive evidence for a spin transfer signal due to the limited statistics.

03.008.012.0)(D

04.013.003.0)(D

LL

LL

Q. H. Xu, Shandong U. arXiv: 0910.1428

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Summary

Comprehensive data from STAR-China Collaboration, provide direct insight to the QCD matter created at RHIC;

STAR-full TOF will extend STAR physics capability

More precise data, more new ideals, more knowledge ….

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Turn-off major sQGP signatures already established at top RHIC energies, see what happens: NCQ scaling? Hadron suppression? Pair correlations in ∆φ&∆η ? hypertriton vs. √sNN ?

1st-order Phase Tran. / Critical Point Elliptic & directed flow Fluctuations & correlations

- Kurtosis analysis on net protons

Search for QCD Critical point the run-10 BES plan:

7.0 GeV       -   1 week 11.5             -   2.5 weeks

17.3             -   2.527.0             -   3.539.0             -   1.5

STAR Collaboration is planning for initial beam energy scan in Run 10 (fall 2009) Primary tool: search for anomalously large particle identified fluctuations with comprehensive particle identification for charged particles provided by TPC + TOFTPC + TOF Fully China’s TOF complete in time for run 10 (fall 2009)

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R&D for New Projects of MRPC

A Muon Telescope Detector (MTD) for STAR:Long strip MRPC

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Many thanks for the STAR collaboration, especially for the Chinese teams.

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ID capability of TOF DetectorsTPC(TPX)- tracking

MRPC TOF (TOFr) – stop time measurement

pVPD/upVPD - start time measurement

Particle momentum;

dE/dx

~8% resolution

/K separation to ~0.6GeV/c

k/p separation to ~1.0GeV/c

Aim at 100ps time resolution TOF system

/K separation to ~1.6GeV/c & k/p separation to ~3.0GeV/c