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Overview of Physics from China’s STAR-TOF Group Yu-Gang Ma

Overview of Physics from China’s STAR-TOF Group Yu-Gang Ma Shanghai Institute of Applied Physics, CAS for the China-STAR Collaboration. Introduction Physics results: (1) PID spectra; (2)heavy quark; (3)Strange quark and Collectivity; (4) Simulation Summary.

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Overview of Physics from China’s STAR-TOF Group Yu-Gang Ma

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  1. Overview of Physics from China’s STAR-TOF Group Yu-Gang Ma Shanghai Institute of Applied Physics, CAS for the China-STAR Collaboration • Introduction • Physics results: • (1) PID spectra; (2)heavy quark; • (3)Strange quark and Collectivity; • (4) Simulation • Summary Workshop on RHIC-STAR full TOF and related Physics, Hangzhou, China; April 27-29, 2009

  2. High-energy Nuclear Collisions jets J/y, D W f X L p, K,K* D, p d, HBT partonic scatterings? early thermalization? Initial Condition - initial scatterings - baryon transfer - ET production - parton dof System Evolves - parton interaction - parton/hadron expansion Bulk Freeze-out - hadron dof - interactions stop Q2 TC Tch Tfo elliptic flow v2 time radial flow bT

  3. IntroductionWhy STAR-TOF ? TPC dE/dxfor low momentum range: π/K 0.6 GeV/c proton/meson 1.0GeV/c • Identified hadron spectra • freeze-out dynamics • hadronization mechanism • Heavy flavor • Identified particle correlations • Chemical and kinetic properties of in-medium jet associated spectra • Fluctuations and correlations • Heavy flavor • Lepton program • In-medium vector meson properties • Heavy flavor TOF will extend momentum range of PID !

  4. PID TPC alone TOF “alone” p k  TOF=110ps 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/c m2 m2

  5. TPC PID hadrons (TPC + TOF) Low & intermediate pT 2.5<pT<3.0 High performance of time resolution PID 0.15 - 4 GeV/c High pT Relativistic rising of dE/dx PID up to 12 GeV/c

  6. Electron identification Lepton decay from heavy quark Electorns mixed with pions if only dE/dx of TPC is used to identify particles Combined with TOF，electrons can be separated from pions cleanly X. Dong, Z.B. Xu, LJ Ruan, J Wu (USTC-BNL) et al

  7. pT PID hadron spectra STAR Collaboration PRL 97 (2006) 152301 At 1.5<pT<7 GeV/c, RCP(p) > RCP() , RCP(p) 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. Centrality dependence of , p pT spectra measured by TOF (red) and TPC-rdE/dx (black).

  8. particle ratios STAR Coll. PRL 97 (2006) 152301 -/+ are consistent with flat at unity in all pT, no significant centrality dependence. pbar/p ratio: no significant centrality dependence, no sign of stronger gluon energy loss [ X.N. Wang, Phys Rev C 58 (1998) 2321 ]. • The p(pbar)/ ratios in Au+Au collisions show strong centrality dependence. In central Au+Au collisions, the p(pbar)/ ratios show an enhancement at intermediate pT range 2-4GeV/c. • In general, parton energy loss models underpredict p/ ratios. No sign of stronger gluon energy loss. • 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).

  9. BW parameters:F. RetierePhys.Rev. C70 (2004) 044907 Light Nuclei The 1st observation of negative v2 at RHIC d 3He d v2 follows A scaling, 3He v2 shows some deviation, need more statistics => coalescence model in nucleonic DOF B2 & sqrt(B3) are consistent Strong centrality dependence

  10. Flow scaling in low energiesnucleonic coalescence Ca+Ca @ 25AMeV For v1,v2: C(A)=5/8(A+3/5) For v3,v4: C(A)=3(A=2/3) Yan, YGM et al., arXiv:0711.0127; Chin. Phys. Lett. 24 (2007)3488; Phys. Lett. B 638 (2006) 50 Directed flow follows A-scaling (C(A)=(A+1)/2): X. Zhang, Z. Xiao, H. Xu, preliminary analysis FOPI data (2009)

  11. Observation of and @ RHIC STAR Preliminary STAR Preliminary 256ps 180ps World data • 1st ever observation of an anti-hypernucleus in the world; • 1st new particle/state created by the RHIC facility. J. H. Chen, talk in QM2009; to be submitted to Sciences

  12. Open charm in p+p and d+Au • Charm semi-leptonic decay measured by TPC + TOF. • Cross section and spectra (prototype TOF) in Run3 p+p, d+Au Phys. Rev. Lett. 94 (2005) 062301

  13. p K TPC e  TPC+TOF |1-1/| < 0.03 Open charm in Au+Au Run 4 Au+Au collisions • D0 reconstructed through K, channel. • Heavy flavor semi-leptonic decay to electrons.

  14. Heavy flavor flow and energy loss D0 STAR Preliminary Tfo = 220 MeV (best fit) – freeze out earlier <t> = 0.23 (best fit), <0.42 (1-). favor moderate or small radial flow. -- dense medium, light flavor thermalization. At high pT, strong suppression ~ 0.3 (light hadron level), seems stagnant to flavor. See Y.F. Zhang’s talk for more details

  15. Final spectra and cross sections Freeze-out/flow parameters and cross-sections are extracted from the combined fit. Charm total cross section scales approximately with Nbin=> evidence of  charm production at initial stage. Full TOF improves (x5) charm hadronic reconstruction

  16. Study B and D Contributions to Non-photonic Electrons via Azimuthal Correlations between Non-Photonic Electrons and Charged Hadrons B D • Non-photonic electron and charged hadron correlations are sensitive to D and B contributions to non-photonic electrons.The preliminary data indicates at pT ~ 4-6 GeV/c the measured B contribution to non-photonic electrons is comparable to D contribution based on PYTHIA model. Our measurement of B/(B+D) provides a constraint to the FONLL prediction.

  17. K- K+ K+ The φ(s-sbar)is a clean probe from early time: K- • Small σ for interactions with non-strange particles • Relatively long-lived (41 fm/c) → decays outside the fireball • Previous measurements have ruled outK+K- coalescence as φ production mechanism → info not “diluted” by hadronic phase φ φ QGP The φ can provide info on particle production mechanisms / medium constituents: φ • The φ is a meson but as heavy as Λ,p baryons • Differentiate between mass-type or meson/baryon- • type dependencies The clean φ is a good probe to understand the strange quark properties, transverse momentum dis. or spin orientation… K- K+ Strange quark dynamics: Why the φ-meson ? The medium produced in HI collisions is very short-lived → we need probes which carry information from the early stage to find out about the medium constituents:

  18. “Since -mesons are made via coalescence of seemingly thermalized s quarks in central Au+Au collisions, the observations imply hot and dense matter with partonic collectivity has been formed at RHIC.” Phys. Rev. Lett. 99, 112301 (2007). Strange quark dynamics:φ-meson production and s-quark flow

  19. We argue that the constitute quark dis. reflects properties of the effective partonic degrees of freedom at hadronization; • Our data indicate that s-quarks have a transverse momentum distribution flatter than that of u/d quarks consistent with hydrodynamic expansion in partonic phase prior to hadronization; • The validity of our approach to explore quark transverse momentum dis. at hadronization has also been tested with independent particle ratios; • Our approach in complement with the consistent quark number scaling in elliptic flow provides a means to measure quantitative quark properties at hadronization of bulk partonic matter Phys. Rev. C 78, 034907 (2008) S-quark pT distribution

  20. S-quark polarization? • Our data are consistent with the un-polarized expectation of 1/3 and thus no evidence is found for the transfer of the orbital angular momentum of the colliding system to the vector meson spin; • Our measurements constrain the possible size of polarization phenomena in the production dynamics of vector mesons. • Phys. Rev. C 77, 061902R (2008) See X.Z. Cai’s talk for more detail; also Q. Xu’s talk

  21. Strange hadron v2 Phys Rev C 77, 054901 (2008) Left plot: larger v2/part indicates stronger flow in more central collisions. Right plot: smaller v2/part in Cu+Cu than in Au+Au; no thermalizatoin in Cu+Cu. See Yan Lv’s talk for more details

  22. near near STAR Preliminary Medium Medium away away Deflected jets Conical emission or deflected jets, need 3-particle correlation? Two component approach: • Correlated to trigger (jets..) • Uncorrelated to trigger (except via anisotropic flow) Bkg normalization 3-particle ZYAM Conical Emission Deflected jets Conical Emission Jet-medium interaction and hadron correlation Shock wave searches in AA collisions Deflected jets or conical emission?

  23. G. Ma et al.,: Phys Lett B 641, 362 (2006); Phys Lett B 647, 122 (2007); Phys. Rev. C 76, 014906 (2007); Nucl. Phys. A 783, 515 (2007) . See G.L. Ma’s talk for new progress in tommorow

  24. Physics results & Impacts • Charm Cross section and spectra in p+p, d+Au, Phys. Rev. Lett. 94 (2005) 062301 • Identified baryon and meson distributions at large transverse momenta from Au+Au collisions at 200 GeV, Phys. Rev. Lett. 97 (2006) 152301 • Partonic flow and -meson production in Au+Au collisions at √sNN = 200 GeV，B. I. Abelev et al. (STAR Collaboration)， 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 • Identified hadron spectra at large transverse momentum in p + p and d + Au collisions at √sNN = 200 GeV,Phys Lett B 637 (2006) 161 • Spin alignment measurements of the K*0(892) and phi(1020) vector mesons in heavy ion collisions at √sNN =200 GeV, Phys. Rev. C77 (2008) 061902(R) • Centrality dependence of charged hadron and strange hadron elliptic flow from √sNN = 200 GeV Au+Au collisions, Phys. Rev. C 77 (2008) 054901 • Mass，quark-number，and dependence of the second and fourth flow harmonics in ultrarelativistic nucleus-nucleus collisions, Phys. Rev. C75（2007）054906 • Energy and system size dependence of \phi meson production in Cu+Cu and Au+Au collisions , Phys. Lett. B 673 (2009) 183 • A few tens talks (plenary+parallel) presented in QM04, SQM04, QM05, SQM06, QM06, QM08, SQM08, QM09 >10 PhD theses, of those: 1 PhD (J.H. Fu/CCNU) won One Hundred Excellent PhD Thesis Award (2005); 1 PhD (X. Dong/USTC), won The Special Presidential Scholarship Award of CAS (2005) 3 PhD (G.L.Ma/SINAP, J. H. Chen/SINAP, Y. F. Zhang/USTC), won The Presidential Award of CAS (2006,2008)

  25. Some theoretical work • Three-Particle Correlations from Strong Partonic Cascade in the AMPT model，G. L. Ma, Y. G. Ma, S. Zhang, X. Z. Cai, J. H. Chen, Z. J. He, H. Z. Huang, J. L. Long, W. Q. Shen, X. H. Shi, C. Zhong, J. X. Zuo, Phys. Letts. B647（2007） 122 • Di-hadron azimuthal correlation and Mach-like cone structure in parton/hadron transport model，G. L. Ma, S. Zhang, Y. G. Ma, H. Z. Huang, X. Z. Cai, J. H. Chen, Z. J. He, J. L. Long, W. Q. Shen, X. H. Shi, J. X. Zuo， Phys Lett B 641 (2006) 62 • Extract charm cross section from its semileptonic decay at RHIC，H. D. Liu, Y.F. Zhang, C. Zhong, Z.B. Xu，Phys.Lett.B639 （2006）441 • Transverse momentum and pseudorapidity dependences of Mach-like correlations for central Au+Au collisions at √sNN = 200 GeV，S. Zhang, G. L. Ma, Y. G. Ma, et al.，PHYS REV C 76, 014904 (2007) • Elliptic flow of $\phi$ meson and strange quark collectivity at RHIC, J. H. Chen, Y. G. Ma, G. L. Ma, X. Z. Cai, Z. J. He, H. Z. Huang, J. L. Long, W. Q. Shen, C. Zhong, J. X. Zuo， Phys. Rev. C74 (2006) 064902 • Statistical interpretation of multiplicity distributions and forward-backward multiplicity correlations in relativistic heavy ion collisions, Jinghua Fu, PHYS REV C 77, 027902 (2008) • Hadron Azimuthal Correlations and Mach-like Structures in a Partonic/Hadronic Transport Model，G.L. Ma, S. Zhang, Y.G. Ma, X.Z. Cai, J.H. Chen, Z.J. He, H.Z. Huang, J.L. Long, W.Q. Shen, X.H. Shi, C. Zhong, J. X. Zuo,Nucl. Phys. A 783 (2007) 515 • Partonic effect on anisotropic flows of baryon for Au+Au at 62.4 and 200 GeV/c，J. X. Zuo et al., Euro. Phys. J. C55 (2008) 463 • Longitudinal broadening of near side jets due to parton cascade, G. L. Ma, S. Zhang, Y. G. Ma, X. Z. Cai, J. H. Chen, C. Zhong,Euro. Phys. J. C57 (2008) 589

  26. Summary • TOF has good performance to identify charged particles. Greatly enhance the PID pT range combining with rdE/dx method. • Since one TOF tray installed at STAR in Run3, many important physics have been measured. , proton spectra, RCP, particle ratios. Light nuclei spectra, v2 and coalescence parameter BA.  and electron from heavy flavor semi-leptonic decays. etc … • Other physics is also very exciting: strange quark dynamics hadron correlation and fluctuation.. • Much exciting physics results are calling once the full barrel TOF detector will be installed in fall of 2009. bright future…. Thanks NSFC, CAS, MoST & DOE for the supports of the TOF project.

  27. Physics results expectedPhysics with Full Barrel TOF - III

  28. MRPCStatus & Plans Status • MRPC Standard production procedure setup • Quality check measurements defined • Web Parameter Database installed

  29. Particle id

  30. The Npart normalized phi meson yields in nucleus-nucleus collisions are found to be enhanced relative to those from p+p collisions with a different trend compared to strange baryons. The enhancement observed in phi mesons ruled out, for the first time, the canonical suppression scenario for strangeness production in high energy nuclear collisions. System size and energy dependence of φ-meson production Phys. Letts. B 673, 183 (2009) See X.Z. Cai’s talk for more detail

  31. three-particle correlation • Strong parton cascade can produce Mach-like wave in central Au+Au collisions Parton cascade? two-particle correlation • Both partonic and hadronics dynamics contribute to the Mach-cone; • The parton cascade is essential to describe the experimental amplitude of Mach-cone structure G. Ma, Y. Ma (SINAP) et al., PLB 641, 362 (2006); PLB 647, 122 (2007)

  32. Heavy flavor physics

  33. Strange quark dynamics

  34. phenomenology • Conical emission

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