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EoS working group

EoS working group. Physics topics in the EoS domain: bulk properties of hot and dense QCD matter What observables are sensitive to this physics? What have we learned so far ? What are the machine, detector and theoretical requirements for future advance ?. Physics Questions to be addressed.

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EoS working group

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  1. EoS working group • Physics topics in the EoS domain: bulk properties of hot and dense QCD matter • What observables are sensitive to this physics? • What have we learned so far ? • What are the machine, detector and theoretical requirements for future advance ? J.Velkovska RHICII meeting,Nov11,2005

  2. Physics Questions to be addressed • The nature of the transition: cross-over or phase transition • Thermodynamics of the bulk: • Is the system thermalized ? • If yes, how is thermalization achieved and on what timescale ? • Can we determine the temperature ? • What is the EoS ? • Character of the medium and dissipative effects: viscosity, heat capacity, speed of sound, diffusion coefficients • Hadronization • Freeze-out J.Velkovska RHICII meeting,Nov11,2005

  3. Is there a phase transition ? Lattice calculations: crossover at m b~ 0 Data: even-by-event net charge and <pT> fluctuations : exclude critical fluctuations at a sharp phase boundary Caveat: unclear if charge fluctuations in QGP can survive hadronization J.Velkovska RHICII meeting,Nov11,2005

  4. Cross-over and critical point • Cross-over implications: Making QGP is a not a Yes/No question ( no sharp boundary between hadrons and QGP) • Goal at RHIC: • Produce matter • with initial T above the cross-over • Study its properties • Where is the tri-critical point ? • Range of estimates from lattice ( sensitive to quark masses used in calculation) , not as certain as the calc. of Tc mbendpoint/ Tc ~ 1 (Gavai, Gupta), ~ 2 (Fodor,Katz), ~ 3 (Ejiri et al) mbfreezout450 MeV (AGS) -- 30 MeV (RHIC) m bfreezout ~ Tc corresponds to sqrt(s) = 25 GeV ( accessible to RHIC but not LHC) • Vary sqrt(s) => look for enhancement in event-by-event fluctuations in <pT> and baryon number • Needs energy scan => luminosity. Krishna Rajagopal (Panic05 talk) J.Velkovska RHICII meeting,Nov11,2005

  5. Lattice: Equation of State • Energy density and pressure: deviations from ideal gas J.Velkovska RHICII meeting,Nov11,2005

  6. Lattice: EoS J.Velkovska RHICII meeting,Nov11,2005

  7. Can we determine the EoS experimentally ? • Connection of the thermodynamic properties of QGP determined from lattice to the data needs to take into account the dynamical effects of the finite nuclear collision system • Microscopic (for the initial state) and macroscopic (hydrodynamics) transport models describe the collective dynamics: EoS is used as an input, local thermal equilibrium is assumed at all stages, system evolution is computed => results compared to data • Observables: identified particle spectra and collective flow J.Velkovska RHICII meeting,Nov11,2005

  8. Hydro compared to data p p elliptic flow PHENIX white paper, nucl-ex/0410003 pT spectra J.Velkovska RHICII meeting,Nov11,2005

  9. Is thermalization achieved ? • Characteristic mass dependence of elliptic flow reproduced by hydrodynamics • Elliptic flow develops in the early stage of the collisions => early thermalization t~ 0.6-1 fm/c • NEED QGP EoS to describe p /p splitting of v2: but most calculations use ideal gas EoS + 1st order phase transition. Is this why HBT doesn’t work ? J.Velkovska RHICII meeting,Nov11,2005

  10. How is thermalization achieved ? • cannot be addressed by hydrodynamic calculations • requires microscopic transport & progress on transport coefficients • Key observables: elliptic flow and nuclear modification factors of D and B mesons => need luminosity • Topic better addressed after detector upgrades: • Phenix: Si vertex detector + PID in Aerogel/TOF • Star heavy flavor tracker + PID in large area TOF J.Velkovska RHICII meeting,Nov11,2005

  11. Current status of charm flow measurements Need detector upgrades + statistics J.Velkovska RHICII meeting,Nov11,2005

  12. Temperature of the medium • Initial: Thermal photos • Difficult measurement . First results from Phenix. • Freeze-out • Chemical • Wealth of data on particle ratios • Described by statistical models • System appears in chemical equilibrium (including strangeness) • Kinetic vs chemical freeze-out • Low-pt W spectra with ~5% error bars – data on tape maybe sufficient • Do we need RHIC II for these measurements? • EM working group says “yes”: need energy scan to disentangle the various contribution to the direct photon spectra J.Velkovska RHICII meeting,Nov11,2005

  13. QGP “EoS” from thermal g& hadron multiplicities • correlatingthermal g slopes & hadron multiplicities (measure of s) • Evolution of the effective # of degrees of freedom, g(s,T), with centrality • Different behaviour for QGP EoS and hadron gas EoS D’Enterria, Perossounko • The system maybe too got in 200 GeV Au+Au to observe a step in the effective degrees of freedom vs T • Proposed: smaller species and lower energies: needs RHIC II luminosity to be doable on a reasonable timescale • However: scepticism that 1) such steps exist 2) calculation correctly relates observable T with the T in hydro J.Velkovska RHICII meeting,Nov11,2005

  14. Properties of the medium beyond ideal hydrodynamics J.Velkovska RHICII meeting,Nov11,2005

  15. How “perfect” is the QGP fluid ? • Ideal Hydro h = 0 – reproduces the main bulk properties observed. Is this enough to conclude that the viscosity is 0? • Deviations from hydro in peripheral collisions, intermediate and high pT, away from mid-rapidity – signal viscous effects and/or incomplete thermalization • Theoretical work on viscous hydro in progress • Hybrid models: hydro+hadronic include viscosity in the hadronic stage. • Need to disentangle the two. Spectra and flow measurements including multi-strange particles and heavy flavor. Detector upgrades needed for improved charm flow measurements. • Can we get the answer from Lattice ? J.Velkovska RHICII meeting,Nov11,2005

  16. Lattice and Viscosity Karsch Not ab initio lattice calculation: hard to do for transport coefficients What is the viscosity? – Answer not coming from Lattice J.Velkovska RHICII meeting,Nov11,2005

  17. U+U to test Hydro limit • Central U+U collisions (nose-on-nose) to increase the initial energy density • Surface/volume decreased • Possible with EBIS • Could be possible before LHC Kuhlman, Heinz J.Velkovska RHICII meeting,Nov11,2005

  18. A method to extract Viscosity Stankus viscosity is a dissipative effect drive local equilibrium towards global equilibrium. So higher viscosity means lower v2, and also lower v3, v4, etc. (v1 is a special case, since it obeys a sum rule). v3 v2 • Colliding asymmetric systems will allow us access to odd values of vn Is v3 more sensitive than v2 to viscosity? • Need A+B running with statistics comparable to Run4/5 • Takes advantage of RHIC flexibility (better than LHC?) Currently work on 3-D hydro and hydro+viscosity Need to combine Hydro with cascade with Reco J.Velkovska RHICII meeting,Nov11,2005

  19. 3D picture of the collisions BRAHMS, PRL88,202301(2002) PHOBOS,nucl-ex/0407012 • Need 3D hydro: can’t assume Bjorken expansion • Ideal 3D hydro does not reproduce the data: viscosity incorporated through cascade • Assymetric system running + detector capabilities at forward rapidity to constrain models Hirano J.Velkovska RHICII meeting,Nov11,2005

  20. (1) q_hat = 0 GeV2/fm (4) dNg / dy = 1000 (2) q_hat = 4 GeV2/fm (3) q_hat = 14 GeV2/fm Diffusion coefficients • Charm v2 and Raa linked to charm diff coeff • Charm number fluctuation liked to diffusion coeff • Need direct charm identification + smaller error bars J.Velkovska RHICII meeting,Nov11,2005

  21. 2.5 < pTtrig < 4.0 GeV/c 1.0 < pTassoc < 2.5 GeV/c Speed of sound: insight from jets? star phenix • A dip in the away-side jet at intermediate pT • Mach shockwaves, Cherenkov radiation • Access to speed of sound and color di-electric constant • Multi-particle correlations = > need statistics • Tagged jets: shrinking of cone for heavy flavor jets = > detector upgrades + luminosity J.Velkovska RHICII meeting,Nov11,2005

  22. hadronization • Hydro/reco/pQCD • Raa, v2, baryon/meson ratios with PID to high-pt • Multi-strange baryons : need more statistics that run4 • phi flows … but needs more stat to test flow per quark • Charm - better to do a direct PID to study flow and Raa. • Correlations with identified leading particles including multi-strange and charm • Baryon vs charge transport to test baryon junctions • PID upgrades needed, luminosity to get the correlation measurements and the heavy flavor measurements J.Velkovska RHICII meeting,Nov11,2005

  23. Summary • We have learned a great deal about the bulk properties of QCD matter from the present data. In many cases the theory is “catching” up. • Need energy and species scans to “turn off” QGP and follow the evolution of the EoS. Asymmetric collisions maybe of help to guide and constrain the theory. • Key physics questions: EoS, thermalization, viscosity, hadronization • Key observables are (mostly) in the heavy flavor sector, but the more abundant species need to be re-measured in different systems/energy • Detector requirements: PID and vertex upgrades, forward capabilities • Machine requirements: Many measurements can be done with design luminosity, but to accomplish the species and energy scans in a reasonable time, we need RHIC II luminosity J.Velkovska RHICII meeting,Nov11,2005

  24. Summary II Note1: These ellipses mark the Beginning ( not the end of the outlined measurements) Note2: We need to communicate between the two writing groups EoS + forward measurements + energy and species scans J.Velkovska RHICII meeting,Nov11,2005

  25. People who contributed talks in the EoS working group: F.Karsch, W. Fischer,T. Hirano, D. Teaney, V. Greco, D. d’Enterria, S.Panitkin, R. Witt, A. Kuhlman, P. Stankus, J. Thomas, L. Ruan, G. van Nieuwenhuizen, M. Lamont, A. Milov, E. Kistenev + many others contributed discussions in the meetings and/or mailing list J.Velkovska RHICII meeting,Nov11,2005

  26. Back-up slides J.Velkovska RHICII meeting,Nov11,2005

  27. Models for Thermalization • cannot be addressed by hydrodynamic calculations • requires microscopic transport & progress on transport coefficients • Mrowczynski, Lenaghan and Strickland & Dumitru, Nara: plasma instabilities - signature would be EM radiation along beam axis in the 0.1 to 1 GeV range • Heavy-quark EFT (van Hees & Rapp) • Multi-gluon processes in a PCM (C. Greiner & Z. Xu) • Classical fields + particle degrees of freedom (Molnar) • Brueckner-type many-body calculations (Mannarelli & Rapp) • Critical opacity at the phase transition (Aichelin & Gastineau) • need more ideas/groups • timescale unknown J.Velkovska RHICII meeting,Nov11,2005

  28. V2q from p, p, K, L Coalescence can predict v2D for v2c = 0 Recombination and charm flow V2 of electrons Direct charm better J.Velkovska RHICII meeting,Nov11,2005 V.G. et al., PLB595 (04) 202

  29. Duke Recent Reco progress • Higher fock states now included • Resonances now included • Neither have big effect • breaking of the scaling at high pT to be test Greco J.Velkovska RHICII meeting,Nov11,2005

  30. HBT and Energy scan No peak seen in data so far. • Energy scan could find the soft point • need comparison to next generation of hybrid and micro models Panitkin J.Velkovska RHICII meeting,Nov11,2005

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