Physics with identified particles at STAR

1. Physics with identified particles at STAR LijuanRuan for the STAR Collaboration (Lawrence Berkeley National Laboratory) Outline: • STAR Detector configuration • Motivation • -- What has been observed at RHIC • -- What still needs to be addressed • Highlight results of identified particle physics from STAR • -- Low pT: bulk property • -- Intermediate pT: coalescence • -- High pT: parton energy loss • Summary QM2006, Shanghai, Nov. 14, 2006

2. The STAR Detector Large acceptance: 2 coverage at mid-rapidity Magnet Coils Central Trigger Barrel (CTB) ZCal Time Projection Chamber (TPC) Year 2000 Barrel EM Cal (BEMC) Silicon Vertex Tracker (SVT)Silicon Strip Detector (SSD) FTPCEndcap EM CalFPD TOFp, TOFr FPD Year 2001+ PMD Future upgrade: Time of Flight, DAQ1000, Heavy Flavor Tracker, Muon Telescope Detector QM2006, Shanghai, Nov. 14, 2006

3. What has been observed at RHIC The theory-experiment comparison suggests that central Au+Au collisions at RHIC produce dense, rapidly thermalizing matter characterized by • Initial energy densities above the critical values predicted by lattice QCD for establishment of a Quark-Gluon Plasma • Nearly ideal fluid flow, marked by constituent interactions of very short mean free path, established most probably at a stage preceding hadron formation • Opacity to jets STAR Collaboration, NPA 757,102 (2005) QM2006, Shanghai, Nov. 14, 2006

4. EOS and thermalization Freeze out properties v2 scaling and baryon enhancement: coalescence Jet quenching: parton energy loss Energy dependence: testing model prediction (coalescence and jet quenching) Heavy flavor yields and flow:color screening and partonic collectivity. Thermometers: dilepton, photon heavy quarkonium species. Jet fragments taggedby a hard direct photon, a heavy flavor forwardjet correlation: CGC What still needs to be addressed • Energy and system size dependence of v2, fluctuation • Three particle correlation •  K p at low pT, light nuclei production • Correlation and fluctuation • K*, , KS, Λ, , , , K, p v2 and RCP • Baryon/meson-charged hadron correlation • PID spectra at high pT • Pbar and pion: Casimir factor CA/CF=9/4 • Charm and bottom: dead cone • Energy dependence of identified particle production Topic in black color, see M. Calderon’s talk QM2006, Shanghai, Nov. 14, 2006

5. Elliptic flow and its fluctuation Consistent v2/ scaling for all energies and collision systems. • S. Voloshin’s talk(2.4) First measurement of v2 fluctuation. v2/<v2> ~36% observed. central peripheral • P. Sorensen’s talk(2.4) QM2006, Shanghai, Nov. 14, 2006

6. v1 measurement v1 depends on energy, not on system size. • G. Wang’s talk(3.4) v4/v22 measurement, see Y. Bai’s talk(2.4) QM2006, Shanghai, Nov. 14, 2006

7. STAR preliminary near Medium away mach cone near 0-12% 200 GeV Au+Au Medium away deflected jets Hard-soft correlations • Hard-soft: away-side spectra approaching the bulk. • Mach-cone shock waves: a fast thermalization mechanism through dispersing energy into collective modes of shock waves. • M. Horner’s talk(3.2) STAR Collaboration, PRL 95,152301 (2005) QM2006, Shanghai, Nov. 14, 2006

8. d+Au Δ2 0-12% Au+Au 0-12% Au+Au: jet v2=0 Δ2 off-diagonal projection Δ1 Δ1 Df=(Df1-Df2)/2 Three particle correlation • Two Analysis Approaches: • Cumulant Method • 1) Unambiguous evidence for three particle correlations. • Jet-Flowbackground Method • 1) Within a model dependent analysis, evidence for conical emission in central Au+Au collisions pTtrig=3-4 GeV/c pTassoc=1-2 GeV/c • C. Pruneau’s talk(1.3)  J. Ulery’s poster(44) QM2006, Shanghai, Nov. 14, 2006

9. EOS and thermalization Freeze out properties v2 scaling and baryon enhancement: coalescence Jet quenching: parton energy loss Energy dependence: testing model prediction (coalescence and jet quenching) What still needs to be addressed • Energy and system size dependence of v2, fluctuation • Three particle correlation •  K p at low pT, light nuclei production • Correlation and fluctuation • K*, , KS, Λ, , , , K, p v2 and RCP • Baryon/meson-charged hadron correlation • PID spectra at high pT • Pbar and pion: Casimir factor CA/CF=9/4 • Charm and bottom: dead cone • Energy dependence of identified particle production QM2006, Shanghai, Nov. 14, 2006

10. STAR preliminary Kp thermal fit STAR Preliminary Min-Bias 10% central 5% central Fluctuation and freeze-out dynamics at RHIC STAR preliminary K/ fluctuation: similar in 62 and 200 GeV Positive long range  correlation observed  B. Srivastava poster(101) • STAR Preliminary • S. Das’s poster(107) Tch (GeV) Energy scan to map out the critical point by measuring K/, p/ fluctuation and identified particle spectra in the future. μB (MeV) • A. Iordanova’s poster(04) QM2006, Shanghai, Nov. 14, 2006

11. STAR Preliminary STAR Preliminary Soft physics measurements vs dNch/d • A. Iordanova’s poster(04) Tkin,<pT>, HBT Radii are strongly correlated with (dNch/dη). nucl-ex/0505014 Lisa et al. • D. Das’s poster(21) QM2006, Shanghai, Nov. 14, 2006

12. Systematics!:s, mT, A+A, pair PID: consistent, detailed map of space-momentum substructure Rinv (fm) Cu+Cu peripheral STAR preliminary STAR preliminary Cu+Cu central mT (GeV/c) Exotic systems! Shifts from non-id! HBT measurement New direction imaging vs Abeam *(1530) mT scaling for space momentum correlation • D. Das’s poster(21) • P.Chaloupka’s poster(106) • R. Witt’s talk(3.1) QM2006, Shanghai, Nov. 14, 2006

13. EOS and thermalization Freeze out properties v2 scaling and baryon enhancement: coalescence Jet quenching: parton energy loss Energy dependence: testing model prediction (coalescence and jet quenching) What still need to be addressed • Energy and system size dependence of v2, fluctuation • Three particle correlation •  K p at low pT, light nuclei production • Correlation and fluctuation • K*, , KS, Λ, , , , K, p v2 and RCP • Baryon/meson-charged hadron correlation • PID spectra at high pT • Pbar and pion: Casimir factor CA/CF=9/4 • Charm and bottom: dead cone • Energy dependence of identified particle production QM2006, Shanghai, Nov. 14, 2006

14. 0-80% Au+Au STAR preliminary STAR preliminary v2 of strangeness hadrons and nuclei in 200 GeV Au+Au collisions Intermediate pT (0.7<pT/n<2GeV/c) • KS K*  Λ  v2: follow NQ scaling. • The centrality dependence of v2: similar to minbias. • Heavy particle: d follows A scaling, 3He follows A scaling at low pT, maybe deviate at higher pTneed more statistics. STAR preliminary  H. Liu’s talk(3.4) • Y. Bai’s talk (KSΛ)(2.4) • X. Dong’s poster (K*)(75) • S. Blyth’s talk ()(3.1) QM2006, Shanghai, Nov. 14, 2006

15. -h correlations _ ifΩ: sss (φss) at intermediate pT come mostly from TTT (TT) No near side correlation! Not consistent with data. • Same-side yield ≠0: • Omegas with pT less than 4.5 GeV/c contain non-thermal • s-quarks: made in jets? Λ - h correlations are similar R. C. Hwa et al., nucl-th/0602024. • J. Bielcikova’s talk(3.1) QM2006, Shanghai, Nov. 14, 2006

16. EOS and thermalization Freeze out properties v2 scaling and baryon enhancement: coalescence Jet quenching: parton energy loss Energy dependence: testing model prediction (coalescence and jet quenching) What still need to be addressed • Energy and system size dependence of v2, fluctuation • Three particle correlation •  K p at low pT, light nuclei production • Correlation and fluctuation • K*, , KS, Λ, , , , K, p v2 and RCP • Baryon/meson-charged hadron correlation • PID spectra at high pT • Pbar and pion: Casimir factor CA/CF=9/4 • Charm and bottom: dead cone • Energy dependence of identified particle production QM2006, Shanghai, Nov. 14, 2006

17. 200 GeV p+p Gluon contribution factor to hadrons • q jets or g jets gluon jet contribution to protons is significantly larger than to pions at high pT in p+p collisions at RHIC; pbar/ < 0.1 from quark jet fragmentation at low beam energy .STAR Collaboration, PLB 637, 161 (2006). • From Kretzer fragmentation function, the g/q jet contribution is similar to AKK. S. Kretzer, PRD 62, 054001 (2000). QM2006, Shanghai, Nov. 14, 2006

18. Particle ratios in 200 GeV Au+Au gluon jet quark jet quark jet At pT>5 GeV/c at RHIC at 200 GeV: p(pbar)/ are larger than the ratios from quark jet. Expectation: pbar/ (Au+Au) < pbar/ (d+Au, p+p). (X.N. Wang, PRC 58, 2321, (1998)) p(pbar)/ (Au+Au) ~ p(pbar)/ (d+Au, p+p). new experimental phenomena R.J. Fries et al., PRC 68, 044902 (2003); R.C. Hwa et al., PRC 70, 024905 (2004); DELPHI Collaboration, Eur. Phy. J. C 5, 585 (1998), Eur. Phy. J. C 17, 207 (2000); W. Liu et al., nucl-th/0607047. STAR Collaboration, PRL 97 (152301) 2006  B. Mohanty’s talk(2.2) QM2006, Shanghai, Nov. 14, 2006

19. Energy dependence of RAA (RCP) Steeper initial jet spectra ? Or Color charge dependence ? At same pT : ~ 3 difference in xT. Q. Wang and X.N. Wang, PRC 71, 014903 (2005) At 1.5< pT < 6 GeV/c:RCP(p+pbar) > RCP() At pT>6 GeV/c, RCP(p+pbar) ~ RCP() Similar to 200 GeV Au+Au collisions.  B. Mohanty’s talk(2.2) QM2006, Shanghai, Nov. 14, 2006

20. Energy dependence of particle composition STAR preliminary • In 62 and 200 GeV Au+Au collisions: • Λ/KS ratio: similar peak positions. • p(pbar)/ ratios: similar shapes at pT>2 GeV/c. system size dependence B. Mohanty’s talk(2.2) QM2006, Shanghai, Nov. 14, 2006

21. Discussion: recombination/coalescence model STAR preliminary • Differences between data and current models: • The p(pbar)/ ratios in energy dependence at pT>2 GeV/c. • R.J. Fries et al., PRC 68, 044902 (2003). • The Ω/Ф ratio at pT>4 GeV/c. • R. C. Hwa et al., nucl-th/0602024. • The Ω-h correlation with 2.5<pT(trigger)<4.5 GeV/c • and 1.5<pT(associate)<pT(trigger) GeV/c. R. C. Hwa et al., nucl-th/0602024.  B. Mohanty’s talk(2.2)  S. Blyth’s talk(3.1) • J. Bielcikova’s talk(3.1) QM2006, Shanghai, Nov. 14, 2006

22. EOS and thermalization: 1) Significant v2 fluctuation 2)3 particle jet correlation: evidence forconical emission. Coalescence 1) Similar shape of p(pbar)/ ratios at pT>2 GeV/c between 62 and 200 GeV 2) The / ratio peaks at pT~4 GeV/c 3) Significant -h correlation at intermediate pT. Jet quenching: parton energy loss The common suppression of pbar and pion  new experimental phenomena Summary • Energy and system size dependence of v2, fluctuation • Three particle correlation •  K p at low pT, light nuclei production • Correlation and fluctuation • K*, , KS, Λ, , , , K, p v2 and RCP • Baryon/meson-charged hadron correlation • PID spectra at high pT • Pbar and pion: Casimir factor CA/CF=9/4 • Charm and bottom: dead cone • Energy dependence of identified particle production Thanks to the STAR Collaboration! QM2006, Shanghai, Nov. 14, 2006

23. STAR QM2006 parallel talks • J.H. Chen --- Spin alignment of vector mesons (K*, ) in Au+Au and p+p collisions at 200 GeV. • H. Liu (3.4) --- Yields and elliptic flow of d(dbar) and 3He(anti-3He) in Au+Au collisions at 200 GeV. • G. Wang (3.4) --- Incident-energy and system-size dependence of directed flow. • Y. Bai (2.4) --- v2, v4 centrality, pT and particle-type dependence in Au+Au collisions at RHIC • I. Selyuzhenkov (3.4) --- Global polarization of Lambda hyperons in Au+Au collisions at RHIC • S. Voloshin (2.4) --- Energy and system size dependence of elliptic flow and v2/ε scaling • J. Putschke (1.3) --- Near-side  correlations of high-pT hadrons from STAR • B. Mohanty (2.2) --- Properties of particle production at large transverse momenta in Cu+Cu and Au+Au collisions at RHIC energies • M. Horner (3.2) --- Low and intermediate pT azimuthal di-hadron correlations from 200 GeV Au+Au collisions measured in STAR • J. Bielcikova (3.1) --- High pT azimuthal and pseudorapidity correlations with strange baryons and mesons at RHIC • X. Lin (2.2) --- Study B and D contributions via azimuthal correlations between non-photonic electrons and charged hadrons • C. Zhong (2.1) --- Scaling of charm integrated cross section and modification of its transverse momentum spectra in d+Au and Au+Au collisions at RHIC • R. Witt (3.1) --- 0(1530) production in heavy ion collisions and its implications for t(therm-chem) • S. Blyth (3.1) --- A measurement of the centrality dependence of the N()/N() ratio and  anisotropic flow • P. Djawotho (3.1) --- Quarkonium production at STAR • S. Chattopadhyay (3.2) --- Azimuthal -charged hadron correlations in d+Au and p+p collisions from STAR at 200 GeV • M. Russcher (3.3) --- Direct photon production in p+p and d+Au collisions at 200 GeV from STAR • P. Sorensen (2.4) --- First measurements of elliptic flow fluctuations • C. Pruneau (1.3) --- Is there a Mach-cone? – Three particle azimuthal correlations from STAR • L. Molnar (1.1) --- Probing small-x gluons and large-x quarks: jet-like correlations between forward and mid-rapidity in p+p, d+Au and Au+Au collisions at STAR • J. Wu (1.4) --- A barrel TOF for STAR at RHIC • A. Rose (1.4) --- A heavy flavor tracker for STAR QM2006, Shanghai, Nov. 14, 2006

24. STAR QM2006 posters • P. Chaloupka --- - correlations in d+Au and Au+Au collisions at STAR • S. Das --- Strangeness fluctuations at RHIC • T. Tarnowsky --- Energy and system size dependence study of percolation phase transition • R. Raniwala --- Elliptic flow of inclusive photons and charged particles in Cu+Cu collisions at 200 GeV • J. Ulery --- Are there Mach cones in heavy ion collisions? Three particle azimuthal correlations in STAR • J. Bouchet --- Performance studies of the silicon detectors in STAR towards microvertexing of rare decays. • M. Cosentino --- Upsilon measurement in STAR • A. Iordanova --- System size dependence of freeze-out properties at RHIC • D. Das --- Identical Meson Interferometry in STAR Experiment • X. Dong --- K* production in Au+Au collisions at RHIC • H. Gose --- Proton femtoscopy in STAR • A. Knospe --- Strangeness and heavy flavor production • G. Lin --- The inclusive photon and charged particle v2 at 200 GeV in Au+Au and Cu+Cu collisions. • R. Longacre ---  scaled correlation signals which increase with centrality of Au+Au collisions at 200 GeV • T. Nayak --- Net charge fluctuations using high order cumulants • P. Netrakanti --- Mechanism of particle production in p+p and d+Au collisions • M. Shao --- A study of the intrinsic time resolution of MRPC used in STAR-TOF • S. Monika --- Energy and system size dependence of photon production • B. Srivastava --- Understanding the particle production mechanism with correlation studies using long and short range correlations and the balance function • A. Timmins --- The centrality dependence of strange baryon and meson production in Cu+Cu and Au+Au relativistic heavy ion collisions with 200 GeV QM2006, Shanghai, Nov. 14, 2006

25. STAR Collaboration U.S. Labs: Argonne, Lawrence Berkeley, and Brookhaven National Labs U.S. Universities: UC Berkeley, UC Davis, UCLA, Caltech, Carnegie Mellon, Creighton, Illinois-Chicago, Indiana, Kent State, MIT, MSU, CCNY, Ohio State, Penn State, Purdue, Rice, Texas A&M, UT Austin, Washington, Wayne State, Valparaiso, Yale Brazil: Universidade de Sao Paolo China: IHEP - Beijing, IPP - Wuhan, USTC, Tsinghua, SINAP, IMP Lanzhou Croatia: Zagreb University Czech Republic: Nuclear Physics Institute England: University of Birmingham France: Institut de Recherches Subatomiques Strasbourg, SUBATECH - Nantes Germany: Max Planck Institute – Munich University of Frankfurt India: Bhubaneswar, Jammu, IIT-Mumbai, Panjab, Rajasthan, VECC Korea: Pusan Nat’l University Netherlands: NIKHEF Poland: Warsaw University of Technology Russia: MEPHI – Moscow, LPP/LHE JINR – Dubna, IHEP – Protvino Thanks! QM2006, Shanghai, Nov. 14, 2006