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From Glasma to Plasma in Heavy Ion Collisions

From Glasma to Plasma in Heavy Ion Collisions. Raju Venugopalan Brookhaven National Laboratory. Topical Overview Talk, QM2008, Jaipur, Feb. 4th, 2008. What is the Glasma ?. Ludlam, McLerran, Physics Today (2003 ). Glasma (Glahs-maa): Noun: non-equilibrium matter

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From Glasma to Plasma in Heavy Ion Collisions

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  1. From Glasma to Plasmain Heavy Ion Collisions Raju Venugopalan Brookhaven National Laboratory Topical Overview Talk, QM2008, Jaipur, Feb. 4th, 2008

  2. What is the Glasma ? Ludlam, McLerran, Physics Today (2003) Glasma (\Glahs-maa\): Noun:non-equilibrium matter between Color Glass Condensate (CGC) & Quark Gluon Plasma (QGP)

  3. Initial conditions for the QGP: • How does bulk matter flow in the Glasma influence transport in the perfect fluid ? • How do jets interact with the Glasma ? Why is the Glasma relevant ? Glasma fields are among strongest Electric & Magnetic fields in nature. What are their properties ? • Intrinsic interest: The Glasma is key to quantitative understanding of matter produced in HI collisions

  4. Little Bang Big Bang Hot Era WMAP data (3x105 years) QGP Inflation CGC/ Glasma Plot by T. Hatsuda

  5. Big Bang vs. Little Bang Other common features: topological defects, turbulence ?

  6. Renormalization Group (JIMWLK/BK) equations sum leading logs and high parton densities • Successful CGC phenomenology of HERA e+p; NMC e+A; RHIC d+A &A+A Review: RV, arXiv:0707.1867, DIS 2007 Before the Little Bang Bremsstrahlung  SY • Nuclear wavefunction at high energies + Recombination = Saturation:

  7. >> 1 Theory developments: running coupling in BK Balitsky;Albacete,Gardi,Kovchegov,Rummukainen,Weigert • Upcoming test: current RHIC d+Au run - eg., forward di-jets (talk by C. Marquet) Hadron wave-fns: universal features CGC Effective Theory = classic fields + strong stochastic sources S(QS2) << 1 T. Ullrich (see talk) -based on Kowalski, Lappi, RV ; PRL 100, 022303 (2008)

  8. How is Glasma formed in a Little Bang ? • Problem: Compute particle production in field theories with strong time dependent sources

  9. Non-perturbative for questions of interest in this talk strong coupling vs weak coupling Interesting set of issues…not discussed here (talks by Rajagopal and Iancu) Glasma dynamics perturbative vs non-perturbative

  10. (=O(1/g2) and all orders in (g)n) In QCD, solve Yang-Mills Eqns. for two nuclei Glasma initial conditions from matching classical CGC wave-fns on light cone Kovner, McLerran, Weigert Systematic expansion for multiplicity moments

  11. for from extrapolating DIS data to RHIC energies Numerical Simulations of classical Glasma fields Krasnitz, Nara, RV Lappi (see talk) LO Glasma fields are boost invariant

  12. II) LHC Pb+Pb at  = 0 ≈ 950 - 1350 for Npart = 350 (See Armesto talk for other LHC predictions) Gelis,Stasto,RV LO Glasma Multiplicity I) RHIC Au-Au mult. at eta=0 Krasnitz, RV Kharzeev, Levin, Nardi

  13. v2   (initial eccentricity) Hirano et al., ; Drescher,Nara Lappi, RV Flow in the Glasma (I) • Large initial ET  QS & NCGC Nhad consistent with strong isentropic flow. Initial conditions for hydro Hirano, Nara CGC- type initial conditions leave room for larger dissipation (viscosity) in hydro stage ?

  14. Knudsen # K = /R with 1/K =  cS dN/dy /area Partial thermalization fit suggests CGC gives lower v2 than Glauber Drescher,Dumitru, Gombeaud,Ollitrault K0 Flow in the Glasma (II) Partial thermalization and v2 fluctuations: Bhalerao,Borghini, Blaizot,Ollitrault

  15. Glasma v2 Glasma flow important for quantifying viscosity of sQGP Krasnitz, Nara, RV: PLB 554, 21 (2003) Flow in the Glasma (III) • What’s the “pre-thermal” flow generated in the Glasma ? Classical field Classical field / Particle Particle f < 1

  16. pX,pY Such configurations may lead to very anisotropic mom. dists.  Weibel instability (see C. Greiner’s talk) pZ The unstable Glasma (I) Kharzeev,Krasnitz,RV Lappi,McLerran • LO boost invariant E & B fields: • purely longitudinal for  = 0+ • generate small amounts of topological charge

  17. increasing seed size 2500 The unstable Glasma (II) • Small rapidity dependent quantum fluctuations of the LO Yang-Mills fields grow rapidly as • E and B fields as large as EL and BL at time Romatschke, RV:PRL,PRD(2006)

  18. The unstable Glasma (III) Romatschke, RV Frequency of maximally unstable k mode grows rapidly Large angle deflections of colored particles in strong fields (Numerical studies by Frankfurt group - C. Greiner talk)

  19. Turbulent isotropization on short time scales ? Small fluctuation spectrum ab initio in the Glasma: multiplicity moments to NLO Arnold, Moore; Mueller,Shoshi,Wong; Bödeker,Rummukainen I) Anomalously low viscosityII) Large energy loss of jets in strong fields ? (talks by Majumder and Müller) III) Explosive generation of P and CP odd transitions via sphalerons(see Warringa’s talk)

  20. Another example of a small fluctuation spectrum…

  21. Multiplicity to NLO (=O(1) in g and all orders in (g)n ) Gelis, RV + Gluon pair production One loop contribution to classical field Initial value problem with retarded boundary conditions - can be solved on a lattice in real time (a la Gelis,Kajantie,Lappi for Fermion pair production)

  22. O(S) but may grow as NLO and QCD Factorization Gelis,Lappi,RV What small fluctuations go into wave fn. and what go into particle production ? Small x (JIMWLK) evolution of nucleus A -- sum (SY)n terms Small x (JIMWLK) evolution of nucleus B ---sum (SY)n terms

  23. “Holy Grail” spectrum of small fluctuations. First computations and numerical simulations underway Gelis,Fukushima,McLerran Gelis,Lappi,RV From Glasma to Plasma • NLO factorization formula: • With spectrum, can compute T - and match to hydro/kinetic theory

  24. Ridgeology* * Rudy Hwa (see talk) + parallel session Near side peak+ ridge (from talk by J. Putschke,STAR collaboration) Jet spectra Ridge spectra STAR preliminary STAR preliminary inclusive inclusive pt,assoc,cut pt,assoc,cut

  25. Fourier modes of small fluctuation field: O(1) Fourier modes of classical field: O(1/g) (talk by Gelis) Two particle correlations in the Glasma: variance at LO Gelis, RV: NPA 779 (2006), 177 Glasma sensitive to long range rapidity correlations:

  26. iii) Opacity effect in : Strong E & B fields destroy azimuthal correlations because survival probability of larger path lengths in radial direction is small (collimation a la Voloshin/Shuryak) Our take on the Ridge Gelis,Lappi,RV i) Long range rapidity correlations built in at early times because Glasma background field is boost invariant. (These are the “beam” jets.) ii) Rapidity correlations are preserved because matter density dilutes rapidly along the beam direction iv) May explain why features of the ridge persist for both soft and semi-hard associated particles Need detailed models with realistic geometry effects

  27. Conclusions I. Ab initio (NLO) calculations of the initial Glasma in HI collisions are becoming available II. Quantifying how the Glasma thermalizes strongly constrains parameters of the (near) perfect fluid III. Deep connections between QCD factorization and turbulent thermalization IV. Possible explanation of interesting structures from jet+medium interactions

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