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The quest for the holy Grail: from Glasma to Plasma Raju Venugopalan CATHIE-TECHQM workshop, Dec. 14-18, 2009 Color Glass Condensates Initial Singularity Glasma sQGP - perfect fluid Hadron Gas t
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Nuclear wavefunction at high energies At RHIC typical x ~ 0.01. At the LHC, x ~ 5 * 10 -4 Parton Density x= fraction of momentum of hadron carried by parton Glue rules! For glue, Q S 2 = 1-1.4 GeV 2 (RHIC) Q S 2 = 2.6-4 GeV 2 (LHC) Kowalski,Lappi,RV, PRL (2008) Nuclear wave function at high energies is a Color Glass Condensate
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CGC: effective degrees of freedom Fields Sources 1 Time dilated, “frozen” random color charges with weight W[ ] Dynamical gauge fields Classical eqns: RG eqn. for x evolution of source dist.: resums S ln(1/x) and /k T 2 contributions in loop corrections Saturation scale Q S : Non.Pert. scale in W at x 0 grows with x evol. of RG
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From CGC to Glasma Multi-particle production from strong CGC fields: compute systematically properties of strongly correlated Glasma fields after collision Consider T :At LO, can obtain from soln. of classical Yang-Mills eqns. NLO terms are as large as LO for S ln(1/x) - resum to all orders Gelis,Lappi,RV (2008) Glasma factorization => universal “density matrices W” calc. “matrix element”
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in the Glasma At RHIC energies, in central A+A, evolution of W’s is not significant - local Gaussian dist. of sources with variance Q S 2 ; at LHC, evolution is very significant Krasnitz,Nara,RV (2003) System initially very far from equilibrium! (T zz 0 for > 1/Q S ) Lappi,McLerran (2006) Initial gauge field configurations are longitudinal chromo-electric & magnetic fields localized in transverse plane - generate Chern-Simons charge s0 Kharzeev,Krasnitz,RV (2002)
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Glasma flux tubes-I Dumitru,Gelis,McLerran,RV (2008) Conjecture based on pert. calculation: Glasma is a collection of “flux tubes” color screened on transverse distances ~ 1/Q S If conjecture is true, from geometry, must have Non-perturbative (soln. of classical QCD!) computation of double inclusive gluon production in Glasma Lappi,Srednyak,RV:arXiv 0911.2068
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Glasma flux tubes-II Three possible scales for color screening: 1/R, m ( QCD ), Q S For 2 =1, (0.5-2) Q S 2 Color screening radius ~ 0.7-1.4 Q S Quantum evolution of distributions will give additional screening Results of non-pert. computation confirm Glasma flux tube conjecture Flux tube size in same ball park as experiments. Some variation in value depending on observable Iancu,Itakura,McLerran (2002) A.H.Mueller (2003) Long range rapidity correlations -> see Dusling talk arXiv:0911.2720
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Matching Glasma dynamics to Hydro Classical field / Particle Particle f < 1 Current matching of LO Glasma YM computations to hydro - “CGC initial conditions”- assumes instantaneous thermalization But T is far out of equilibrium in LO computations No computations to date fully take into account NLO contributions that are as large as LO and should be resummed… eccentricity
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Unstable quanta in the Glasma Romatschke,RV (2006) Boost non-invariant quantum fluctuations can grow rapidly for > 0 for Strong disordering could lead to rapid isotropization, “anomalous transport” Asakawa,Bass,Muller (2006) Dumitru,Nara,Schenke,Strikland (2008) These quantum corrections, albeit difficult to evaluate, are no less a necessary part of early time dynamics… 3+1-D YM simulations
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Rapid isotropization in the Glasma Resum - extend range of YM-dynamics “Holy Grail” Spectrum of small fluctuations Fukushima,Gelis,McLerran (2006) Gelis,Lappi,RV (2008) Can also compute event by event initial conditions to estimate flow fluctuations: Similar in spirit to the event by event hydro code NeXSPheRIO = NeXus + SPheRIO Grassi et al., arXiv:0912.0703
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Summary The early time dynamics of HI collisions can be computed ab initio in a factorization framework Early time Yang-Mills dynamics reveals structure of the Glasma as a collection of flux tubes color screened on distances ~ 1/Q S Quantum instabilities from the wave-function can lead to early isotropization; significant effects on final states The factorization framework for n-point correlations is ideally suited to event-by-event analysis Many interesting conceptual issues in understanding the Glasma -> sQGP transition
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