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Strange quark dynamics on hot dense matter under the extreme condition

Strange quark dynamics on hot dense matter under the extreme condition. Yu-Gang Ma ( 马余刚 ). (SINAP) Main collaborators: Jin-Hui Chen, Guo-Liang Ma. The 5-th International Conference on Quarks and Nuclear Physics – QNP09, IHEP@Beijing, September 21– 26, 2009. Outline.

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Strange quark dynamics on hot dense matter under the extreme condition

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  1. Strange quark dynamics on hot dense matter under the extreme condition Yu-Gang Ma (马余刚) (SINAP) Main collaborators: Jin-Hui Chen, Guo-Liang Ma The 5-th International Conference on Quarks and Nuclear Physics – QNP09, IHEP@Beijing, September 21– 26, 2009

  2. Outline • Hot dense matter under the extreme condition • Strange -quark dynamics from -meson and W- baryon • s-quark thermalization: production and W/f (PT) • s-quark collectivity: grouping behavior of elliptic flow • s-quark enhancement: f-meson enhancement • s-quark un-polarization: f-meson spin un-alignment • s-quark transverse momentum distribution: W/f (PT/n) • Constraints on the system evolution dynamics • Summary/outlook

  3. Hot Dense Matter under the extreme condition @RHIC: (1) Away-side peak vanishes in Au-Au central collision Trigger particle Associated particles on away side: 4 >pT(assoc) > 2 GeV/c Hard associated particles → suppression (partonic energy loss)‏ 4 < pT(trig) < 6 GeV/c Energy loss leads to re-distribution of Soft associated particles → enhancement (strong jet-medium interaction)‏ 4 >pT(assoc) > 0.15 GeV/c STAR coll, PRL 95 (2005)152301

  4. leading particle hadrons q q ? Hot Dense Matter under the extreme condition: (2) Strong suppression of the High pTparticles Nuclear Modification Factor: nucleon-nucleon cross section <Nbinary>/sinelp+p AA If R = 1 here, nothing new going on

  5. K- K+ K+ Thef-meson is a clean probefrom early time: K- • Smallsfor interactions with non-strange particles[1] • Relatively long-lived (41 fm/c) →decays outside the fireball • Previous RHIC measurements have ruled outK+K- coalescence asfproduction mechanism[2] φ φ QGP φ The f can provide info on particle production mechanisms/medium constituents: K- • The f is a meson but as heavy asL,p baryons (mass vs. particle type?) K+ Why f-meson ? Hot Dense Matter [1] A. Shor, Phys. Rev. Lett. 54 (1985) 1122 [2] J. Adams et al., Phys. Lett. B 612 (2005) 181

  6. STAR TPC used to identify KaonviadE/dx in TPC gas STAR Detector • We used the high-statistics 200 GeV and 62.4 GeV Au+Au and Cu+Cu data to measure the -meson production at STAR The STAR experiment • Event-mixing method used to estimate combinatorial background from uncorrelated K+K- pairs; • Final subtracted minv distribution fitted with Breit-Wigner + straight line.

  7. <pT> f/K- N()/N(K-), ruled out the K+K-coalescence (red dashed line: UrQMD assumes K+K- coalescence mechanism for phi . -meson production at RHIC <pT>: -meson decoupled early UrQMD Evolution in the centrality dependence: Clear change in spectral shape -- Exponential (~thermal) for central collisions -- Power law type (~ hard process) at high pT in peripheral collisions STAR Col. Phys. Lett. B 612, (2005) 181, Phys. Rev. Lett. 99, (2007) 112301

  8. f-meson RCP RCP • mid-central collisions: • RCP of f meson is more consistent with that of K0 rather than L, supporting the baryon/meson grouping behavior. • The observable favors the prediction based on quark Coal/Recom model (s-sbarphi). • peripheral collisions: • The binary scaled f production is very similar to that in p+p and d+Au collisions where strangeness production may be canonically suppressed. • Therefore a baryon-meson scaling behavior of RCP is not expected. SINAP & LBL et al. (for STAR), PRL 99 (2007)112301

  9. At intermediate pT,W(sss)and f(ss)should be dominated by bulk thermal quark coalescence – no jet contribution (Hwa and Yang PRC 75, 054904 (2007)) It appears that thermal quark coalescences dominate the particle production below pT~4 GeV/c in centralAu+Aucollisions Thermalization: f’sare mostly from bulk thermal s quarks SINAP & LBL et al. (for STAR), PRL 99 (2007)112301

  10. Collectivity of quarks: Partonic Collectivity of multi-strange particles py y px x STAR data (S. Shi et al) PHENIX π and p: nucl-ex/0604011v1 NCQ inspired fit: X. Dong et al. Phy. Let. B 597 (2004) 328 Partonic transport model (AMPT Model) calculations: 1. NCQ scaling works well for phi/Omega: strange quark collectivity; 2. Larger v2 reveals in comparison with AMPT default and RQMD case. Partonic interaction is essential to reproduce larger v2 as the data! J. H. Chen, YGM et al., PRC74, 064902(2006); J. X. Zuo, J.Y.Chen, X. Cai, YGM, F. Liu et al., EPJC 55,463(2008)

  11. Strangeness enhancement We do observe strangeness enhancement: yield relative to p+p BUT -meson enhancement: -- Enhancement between net Strangeness = 1 (L, K) and 2 (X) particles -- 200 GeV data > 62.4 GeV The above observations clearly suggest that, at these collision energies, the source of enhancement of strange hadrons is related to the formation of a dense partonic medium in high energy nucleus–nucleus collisions and cannot be alone due to canonical suppression of their production in smaller systems. SINAP & LBL et al. (for STAR), PLB 673 (2009)183

  12. x -Ly in unit of 105 z b/RA • gradient in pz-distribution along • the x-direction • local orbital angular momentum • of the created parton • quark polarized via spin-orbit? • final state hadron polarization? • hyperon polarization • vector meson spin alignment impact parameter Global orbital angular momentum Huge orbital angular momentum of the collisions system may lead to global quark polarization of the system Z.T. Liang (Shandong), X.N. Wang et al., PRL 94, 102301(2005); PLB 629, 20 (2005); arXiv0710.2943[nucl-th].

  13. Vector meson spin alignment： Deviation of ρ00 from 1/3 manifests the alignment of vector mesons; No evidence is found for the transfer of the orbital angular momentum of the colliding system to the vector meson spins. What happen in Experiment? Lambda un-polarization |PL|<0.02 Voloshin et al (STAR Col.) PRC 76, 024915 (2007) J.H. Chen (SINAP), Z. Tang (USTC), I. Selyuzhenkov (STAR), PRC77, 061902(R) (2008) Un-polarization signal of s-quark might imply that the system created at RHIC is isotropic to the extent that, locally, there is no longer a preferred direction. It favors the QGP scenario.

  14. Strange quark PT distributions at Hadronization SINAP, PRC 78 (2008)034907 Can we extract the strange quark pT distribution from multi-strange hadron data? If baryons at pT are mostly formed from coalescence of partons at pT/3 and mesons at pT are mostly formed from coalescence of partons at pT/2, then we could extract quark PT information: • and f particles have no decay feed-down contribution! These particles will freeze-out earlier from the system and have small hadronic rescattering cross sections.

  15. Strange and light quark distribution • The constitute quark pT distributions have been extracted from the multi-strange data; • The s-quark shows a flatter pTdistribution than the d-quark. • The s-quark and d-quark have a similar KET distribution: partons have undergone a partonic evolution possibly described by hydrodynamics.

  16. s/d quark ratio from primordial hyperon • Consistent s/d ratio derived from primordial hyperon data • Sfeed-down: • S(1385)[2]: 26%+-5.9%; • S0: no data available yet • THERMUS[3]: 36% • String frag[4]: 25% [2] B.I. Abelev et al., Phys. Rev. Lett. 97, 132301 (2006); [3] S. Wheaton and J. Cleymans, J. Phys. G 31, S1069 (2005); [4] M. Bleicher et al., J. Phys. G 25, 1859 (1999); H.J. Drescher et al., Phys. Rep. 350, 93 (2001). • s/d ratio from hyperonX0(1530) feed-down[1]: 46%+-14% [1] R. Witt, J. Phys. G 34, S921 (2007);

  17. s/d ratio compared with Reco. model calculation  Good agreement with the data; Large exp. uncertainty; • Quark Reco. model predicted a consistent shape between s/d ratio and the hyperon ratio.

  18. Fit parameter of constituent quark mass Can we put constrains on the constitute quark mass parameter ?

  19. Constraints on the system evolution dynamics • Theoretical model for particle production at RHIC typically involve initial conditions, partonic evolutions, hadronization and hadronic evolutions. • Theoretical uncertainties due to hadronization scheme and hadronic evolution are major issues for quantitative description of properties of QCD medium created at RHIC. eg., the hadronic evolution process have been added to the hydrodynamic models as an afterburner and have been shown to significantly alter the spectra shapes of ordinary hadrons[1].[1] T. Hirano et al., Phys. Rev. C 77, 044909 (2008) Can our derived quark distributions, representing a cumulative effect from initial conditions through partonic evolution, be used to determine the final-state hadron momentum distribution?

  20. Dynamical model calculation (1) • Original version failed to reproduce the spectra data: • Insufficiency parton cascading cross sections in the ZPC model where only pQCD processes have been included? • Wrong choice of hadronization scheme? • A Multi-Phase Transport model[1] • Initial condition: HIJING • Partonic evolution: ZPC • Hadronization: coalescence • Hadronic evolution: ART [1] Z.W. Lin et al., Phys. Rev. C 72, 064901 (2005)

  21. Dynamical model calculation (2) It can faithfully reproduce the data at intermediate pT. • Modified version: • Tuned the initial parton pT distribution inherited from HIJING string melting empirically, (vT0,Tth0); • Requirement: the tuned distributions after parton cascade match our derived s/d quark dis; • Coalescence scheme: two nearest (in coordinate space) quarks  meson while three nearest quarks  baryon. An essential ingredient in Reco./Coa. model calculation: the distribution of effective constituent quarks that readily turn into hadron.

  22. 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. Summary • N(f)/N(K) vs. Npart rules out the K+K- coalescence as a dominant channel for f production at RHIC; • N(W)/N(f) vs. pT favors the model prediction that fs are made via thermalied s-quarks coalescence at RHIC; • N(W)/N(f) and N(X)/N(f) vs. pT/nq indicate the s-quark and d-quark have a similar KET distribution: partons have undergone a partonic evolution possibly described by hydrodynamics; the distribution of effective constituent quarks can reproduce the reasonable hyperon Pt distribution. • v2(f) vs. pT concludes that the partonic collectivity has been formed at RHIC; • Un-polarization signal of s-quark might imply that the system created at RHIC is isotropic to the extent that, locally, there is no longer a preferred direction. Again, favors the QGP scenario.

  23. All 120 TOF trays are installed at STAR and data will be taken in next RHIC runs PID information for > 95% of kaons and protons in the STAR acceptance Clean e± ID down to 0.2 GeV/c STAR-China Collaboration plan: 120 trays of MRPC modules which leverage MRPC development at CERN (Crispin Williams et al) Development of HPTDC Chip STAR-MRPC TOFs are contributed from the China-STAR group Fully complete in time for run 10 (fall 2009)‏ Phi reconstruction from e+e- • /K separation to 1.6 GeV/c • 0.7 for TPC alone • (+K)/p to p = 3 GeV/c • 1.2 for TPC alone • Clean electron ID down to 0.2 GeV TOF+TPC : one kaon from φ identified by TPC, the other by TOF TPC+TPC : the 2 kaons from φ identified using only TPC

  24. Violation of the NCQ scaling for the identified-particle elliptic flow may indicate the hadronic dominant phase is coming. RHIC low energy scan: the breaking of NCQ scaling of elliptic flow? J. Tian, J. H. Chen, Y. G. Ma et. al., Phys. Rev. C 79, 067901 (2009) Y.G.Ma

  25. Away side: Phi/Omega-trigged correlation functions are narrower than the hadrons-trigged correlation function it is consistent with the scenario of earlier freeze-out of phi/omega production YGM, JPG 32(2006)S373, SQM06 Di-hadron correlation in the AMPT model:Black: trigged by  orΩ; Blue: trigged by any hadron

  26. Many Thanks for STAR collaborators, especially for Jinhui Chen, Guoliang Ma, Xiangzhou Cai, Huanzhong Huang, Nu Xu et al.

  27. Creation of the Hot Dense Matter under the extreme condition at RHIC heavy ion collisions Away-side peak vanishes in Au-Au central collision@200GeV/c  dense matter Strong suppression of the High Pt meson Hot dense matter RHIC creates hot and dense matter, parton loss energy when traverse the medium. RHIC white paper: Nucl. Phys. A 757

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