Report

Dynamic Modeling for Relativistic Heavy Ion Collisions Huichao Song Peking University CPOD2014, Bielefeld, Germany, Nov.17-Nov.21, 2014 11/20/2014 QGP-the most perfect fluid in the world? BNL News, 2005 How perfect is the QGP fluid? What is viscosity Shear viscosity – measures the resistance to flow act against the buildup of flow anisotropy Bulk viscosity – measures the resistance to expansion act against the buildup of radial flow Heat conductivity – measures the ability of heat transfer Assume: 0, n 0 (RHIC&LHC) Hydrodynamics & its Hybrid Model Viscous Hydrodynamics T (x) 0 T ( e p )u u ( p ) g Evolution equations for shear pressure tensor 2 1 2 ( u ) 1 2 T T and bulk pressure u T u T Assume zero net baryon density & heat conductivity at RHIC and the LHC Song & Heinz PLB08, PRC08 2+1-d: OSU, INT, Stony Brook, Pudue, Calcutta (2008), Crakow, Frankfurt(2010) … … 3+1-d: Mcgill(2011), MSU(2012), Crakow(2012), Nagoya(2013)… … Viscous Hydro + Hadron Cascade Hybrid Model QGP Initial conditions viscous hydro HRG HRG hadron cascade ideal hydro (QGP & HRG) viscous hydro (QGP & HRG) viscous hydro (QGP) + URQMD (HRG) H. Song, S. Bass, U. Heinz, PRC2011 Event-by-event hydrodynamics Single shot simulations: smoothed initial conditions (before 2010) E-b-E simulations: fluctuating initial conditions (since 2010) B. Schenke et al, Phys.Rev. C85, 024901 (2012) Extracting QGP viscosity from elliptic flow data – VISHNU results VISHNU hybrid model & QGP viscosity H. Song,et.al, PRL2011 MC-KLN MC-Glauber 1 (1 4 ) ( / s )QGP 2.5 (1 4 ) -Main uncertainties come from initial conditions -Other uncertainties (much smaller) -Initial flow, bulk viscosity, single shot vs. e-b-e calculations (each of them shift V2 by a few percent, partial cancellation among them) V2 at RHIC and LHC Song, Bass & Heinz, PRC 2011 The average QGP viscosity is roughly the same at RHIC and LHC LHC: spectra for identified hadrons Song, Bass & Heinz,PRC 2014 -a nice fit of spectra for pions, kaons and proton Spectra of Strange & Multi-strange Hadrons X.R. Zhu, H. Song et al., in preparation -a nice fit of spectra for Lambda, Xi, and Omega V2 ( pT ) for pions, kaons & protons at LHC VISHNU Song, Bass & Heinz,PRC 2014 ( / s )QGP 0.20 A very nice fit of V2(PT) for all centrality bins at LHC from VISHNU hybrid model v2 of Strange & Multi-strange Hadrons X.R. Zhu, H. Song et al., in preparation -Nice descriptions of Lambda, Xi and Omega V2 at various centralities Initial State Fluctuations, Final State Correlations & the QGP viscosity Uncertainties from Initial Conditions H. Song, S. Bass, U. Heinz, T. Hirano, and C. Shen, PRL2011 MC-KLN MC-Glauber 1 (1 4 ) ( / s )QGP 2.5 (1 4 ) Main uncertainties come from initial conditions MC-KLN, larger 2 HIGHER value of QGP viscosity MC-Glauber, smaller 2 LOWER value of QGP viscosity MC-KLN & MC-Glauber initializations & V3 Pure viscous hydro simulations : v2 / 2 MC KLN, / s 0.20 v3 / 3 MC KLN, / s 0.20 V3 prefer lower value of QGP viscosity Qiu, Shen & Heinz, PLB2012 v2 / 2 MC Glb, / s 0.08 v3 / 3 MC Glb, / s 0.08 Initialization & Pre-equilibrium: Updates after 2011 -fluctuations of nucleon positions: MC-Glauber, MC-KLN -fluctuations of color charges (in the framework of CGC): IP-Glasma: B. Schenke et al., arXiv:1202.6646; 1206.6805 [nucl-th] Correlated Fluctuation: B. Muller & A. Schafer, arXiv:1111.3347 [hep-ph] . -fluctuations of local gluon numbers (in the famework of MC-KLN): Multiplicity fluctuations: A. Dumitru and Y. Nara, Phys. Rev. C 85, (2012) 034907 -Pre-equilibriums: URQMD initialization: H.Petersen & M. Bleicher, Phys. Rev. C81, 044906,2010 AMPT initialization: L. Pang, Q.Wang & X.Wang, arXiv:1205.5019[nucl-th] EPOS/NEXUS initialization: K. Werner et al., Phys. Rev. C83:044915,2011 …… …… Mostly, the effects of initializations /pre-equilibrium dynamics was studied with ideal hydro. Their quantitative influences on ( / s)QGP are still unknown. Flow at RHIC & LHC: results from IP-Glasma + MUSIC Gale, Jeon ,Schenke, Tribedy &Venugopalan PRL2013 New Observables for Higher Order Flow Harmonics Luzum & Ollitrault, 2012-10 Qiu & Heinz,12-08 C. Gale et al. 12-09 -They are all sensitive to the QGP viscosity -A further study of flow data in different aspects, using e-b-e hybrid model will constrain initialization models, tightening the limit on ( / s ) QGP Massive Data evaluation Exp Observables - particle yields - spectra - elliptic flow - triangular flow & higher order flow harmonics - event by event Vn distributions - higher-order event plane correlations … ... … … Theoretical Inputs: - type of initial conditions - initial flow - starting time - EoS - shear viscosity - bulk viscosity - relaxation times - freeze-out/switching cond. …… …… Massive data evaluation Early CHIMERA Results (Comprehensive Heavy Ion Model Evaluation and Reporting Algorithm) Spectra spectra elliptic flow HBT R. Soltz, et al., PRC2013 Please also refer to the work from MSUDUKE collaboration, arXiv: 1303.5769 Bernhard & Bass, JET collaboration Massive data evaluation Bulk Viscosity Long , but not full lists of articles: K. Rajagopal et al. JHEP 1003, 018(2008) . R.Fries et al. Phys.Rev. C78 034913 (2008) . G.Torrieri et al. Phys.Rev. C78, 021901(2008). A. Monnai et al. Phys.Rev. C80 054906 (2009) H.Song and U.WHeinz, Phys. Rev. C81, 024905 (2010) P. Bozek, Phys. Rev. C81, 034909 (2010) K.Dusling and T.Schäfer, Phys.Rev.C 85, 044909 (2012) J.Noronha-Hostler, et.al., Phys.Rev. C 88, 044916 (2013) J.Noronha-Hostler, J.Noronha and F.Grassi, arXiv:1406.3333 [nucl-th] M. Habich and P. Romatschke, arXiv:1405.1978 [hep-ph]. … … … … … … The interplay between shear and bulk viscosity ideal shear visc. shear+ bulk visc. QGP Visc. suppression of elliptic flow Song & Heinz PRC09 HRG Min. AdS/CF T predictio n -Bulk viscous effects are much smaller than shear ones due to the critical slowing down near phase transition (Song & Heinz PRC09) -One can extract the QGP shear viscosity from exp data without large contamination from bulk viscosity Ultracentral Collisions: bulk visc. & NN correlations Shen, Qiu and Heinz 2013 G. Denicol, QM2014 -MC-Glauber & MC-KLN: can not simultaneously fit V2 and V3 -IP+Glasma + NN correlations + bulk viscosity nicely reproduces Vn in ultra-central collisions Soft Particle Yields, Chemical & thermal Freeze-out at the LHC J. Stachel,SQM 2013 Tch = 165MeV v.s. Tch = 150MeV dN/dy for identified hadrons (RHIC & LHC) Song, Bass & Heinz,PRC 2014 RHIC : 200 A GeV Au+Au LHC : 2.76 A TeV Pb+Pb -VISHNU nicely describes the multiplicity for pions, kaons & protons -B-Bbar annihilations plays an important role for a nice fit of the proton data VISHNU : Tsw= 165MeV Please also refer to F. Becattini et al., PRC2012 dN/dy for identified hadrons (LHC) X.R. Zhu, H. Song et al., in preparation -VISHNU nicely describes the multiplicity for various hadrons at the LHC dN/dy for identified hadrons (LHC) X.R. Zhu, H. Song et al., in preparation VISHNU most central collisions Statistical Model vs. VISHNU Statistical Model Statistical Model : Tch ~ 150 MeV VISHNU VISHNU : Tsw= 165MeV - Statistical Model: Tch is extracted from final hadron yields; averaged chemical freeze-out temperature for final stable hadrons - VISHNU: Tsw corresponds QGP chemical freeze-out; different hadrons may have different chemical freeze-out temperature. Chemical freeze-out for various hadrons in UrQMD X.R. Zhu, H. Song et al., in preparation Thermal freeze-out for various hadrons in UrQMD X.R. Zhu, H. Song et al., in preparation -earlier freeze-out for Xi and Omega! phi-meson Elliptic flow for phi at the LHC Song, Bass & Heinz, PRC 2014 -Hadron cascade: small cross sections for phi -mass ordering between phi and proton are independent of collision energies, centralities & theoretical details 200A GeV Au+Au T. Hirano 3+1-d ideal hydro+JAM Elliptic flow for phi at the LHC Song, Bass & Heinz, PRC 2014 ALICE 2014 Elliptic flow for phi at the LHC Song, Bass & Heinz, PRC 2014 STAR Preliminary ALICE 2014 phi V2 in strong & weakly coupling limit Song, Bass & Heinz, PRC 2014 -hydro + Tdec =165 MeV weakly coupling limit -hydro + Tdec =100 MeV strong coupling limit -VISHNU: small cross sections for phi phi V2 in strong & weakly coupling limit Song, Bass & Heinz, PRC 2014 -hydro + Tdec =165 MeV weakly coupling limit -hydro + Tdec =100 MeV strong coupling limit STAR Preliminary VISHNU: small cross sections for phi ALICE 2014 Summary Summary -Extraction / s from elliptic flow data using VISHNU indicates: 1 (1 4 ) / s 2.5 (1 4 ) (MC-Glauber; MC-KLN) -Slightly larger averaged QGP viscosity at the LHC -Recent developments on initialization models: color charge fluctuations; multiplicity fluctuations; initial flow fluctuations … … -New flow data: triangular flow & higher order flow harmonics, higher-order event plane correlations e-b-e vn … ... -To implement e-b-e simulations to further study other flow will help us to constrain initialization models, tightening the limit on ( / s ) QGP -massive data evaluation are needed -VISHNU could nicely describe the yields of various hadrons -B-Bbar annihilations is important to describe the proton yields at the LHC VISHNU: an indication of different chemical freeze-out temperature for various hadrons