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Two particle correlations in the Glasma & the Ridge

Two particle correlations in the Glasma & the Ridge. Raju Venugopalan Brookhaven National Laboratory. AGS users meeting, May 27th, 2008. For particles to have been emitted from the same Event Horizon , causality dictates that. If Y is as large as (especially) suggested by

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Two particle correlations in the Glasma & the Ridge

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  1. Two particle correlations in the Glasma & the Ridge Raju Venugopalan Brookhaven National Laboratory AGS users meeting, May 27th, 2008

  2. For particles to have been emitted from the same Event Horizon, causality dictates that If Yis as large as (especially) suggested by PHOBOS, correlations were formed very early - in the Glasma…

  3. An example of super horizon fluctuations…

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

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

  6. Z Z T T Lappi, McLerran, NPA772 (2006) After a HI collision, classical fields form a Glasma flux tube with longitudinal chromo E & B fields Typical size of flux tube in transverse direction is 1 / QS < 1/QCD Systematic framework for multi-particle production in the Glasma - Gelis, Lappi, RV, arXiv:0804.2630

  7. QCD vacuum and sphaleron transitions Kharzeev, Krasnitz, RV, Phys. Lett. B545 (2002) “Over the barrier” sphaleron transitions can change the topological charge in an event => the index theorem tells us that this induces a induce a net chirality. Vacua labeled by different Chern-Simons #  EB

  8. Two particle correlations in the Glasma Can it explain the near side ridge ?

  9. 2 particle correlations in the Glasma (I) Dumitru, Gelis ,McLerran, RV, arXiv:0804.3858[hep-ph]] = + Leading (classical) contribution Note:Interestingly, computing leading logs to all orders, both diagrams can be expressed as the first diagram with sources evolved a la JIMWLK Hamiltonian Gelis, Lappi, RV (2008)

  10. 2 particle correlations in the Glasma (II) Leading color “topologies”: “single diffractive” “interference” graph

  11. 2 particle correlations in the Glasma (III) Suppressed color “topologies”: “single diffractive” (emission from different quark lines in amp. and complex conjugate amp.) “double diffractive”

  12. 2 particle spectrum (II) Simple “Geometrical” result: •  4 (more accurate result requires numerical soln. of YM eqns. - in progress. with K_N  0.3

  13. R 2 particle spectrum (III) Particle emission from the Glasma tubes is isotropic in the azimuth Particles correlated by transverse flow (or at high pT by opacity effects) are highly localized transversely - experience same transverse boost Voloshin, Shuryak Gavin, Pruneau, Voloshin

  14. 2 particle spectrum… Centrality dependence of Vr from blast wave fits Centrality dependence of QS a la Kharzeev-Nardi

  15. Ridge from flowing Glasma tubes KN ~ 0.1 STAR preliminary (energy & centrality dep. of flow parametrizaton courtesy of P.Sorensen) • Gets many features right: i) Same flavor composition as bulk matter ii) Large multiplicity (1/3rd) in the Ridge relative to the bulk iii) Ridge independent of trigger pT-geometrical effect iv) Signal for like and unlike sign pairs the same at large 

  16. Ridge from flowing Glasma tubes Caveat: Angular dist. appears to require larger boosts, or absorption by medium a la Shuryak Blast wave picture may be too simplistic - need more accurate description of transverse flow profile

  17. SUMMARY • Long range rapidity correlations are formed early - in the Glasma • Multi-particle emission from radially flowing Glasma flux tubes provide a dynamical picture of the ridge. • The analysis can be improved by better treatment of I) transverse flow & II) rapidity evolution of rapidity interval between the pairs

  18. EXTRA SLIDES

  19. Some possible ridge explanations In medium radiation and longitudinal flow push N.Armesto et.al Phys.Rev.Lett. 93(2007) 242301 QCD bremsstrahlung radiation boosted by transverse flow S.A.Voloshin, Phys.Lett.B. 632(2007)490 E.Shuryak, hep-ph:0706.3531 Broadening of quenched jets in turbulent color fields A.Majumder et.al Phys. Rev. Lett.99(2004)042301 Recombination between thermal and shower partons at intermediate pT R.C. Hwa & C.B. Chiu Phys. Rev. C 72 (2005) 034903 Momentum Kick Model C.Y. Wong hep-ph:0712.3282 All qualitatively consistent with the features of ridge • New approaches used in to attempt to disentangle • System size dependence • Identified particle correlation • Di-hadron correlation with respect to reaction plane • 3-particle correlation

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