Understanding Energy Loss of Heavy Quarks William Horowitz The Ohio State University June 2, 2009 With many thanks to Brian Cole, Yuri Kovchegov, and Ulrich Heinz 2009 RHIC and AGS Users’ Meeting

2009 RHIC and AGS Users’ Meeting Outline Introduction pQCD AdS/CFT pQCD Again Conclusions 2009 RHIC and AGS Users’ Meeting

2009 RHIC and AGS Users’ Meeting The Heavy Flavor Data STAR, Phys. Rev. Lett. 98, 192301 (2007) PHENIX, Phys. Rev. Lett. 98, 172301 (2007) 2009 RHIC and AGS Users’ Meeting

Simultaneous Understanding? Y. Akiba for the PHENIX collaboration, hep-ex/0510008 STAR, Phys. Rev. Lett. 98, 192301 (2007) WHDG C. Vale, QM09 Plenary (analysis by R. Wei) PHENIX, Phys. Rev. Lett. 98, 172301 (2007) 2009 RHIC and AGS Users’ Meeting

RAA vs. v2 Anti-correlation WH, Acta Phys.Hung.A27:221-225,2006 p0 Cu+Cu PHENIX, arXiv:0903.4886 2009 RHIC and AGS Users’ Meeting

2009 RHIC and AGS Users’ Meeting pQCD 2009 RHIC and AGS Users’ Meeting

2009 RHIC and AGS Users’ Meeting Hard Spectra PHENIX, 0903.4851 [hep-ex] A Dion, Quark Matter 2009 pT [GeV/C] 1 9 J Dunlop, QM09 2009 RHIC and AGS Users’ Meeting

2009 RHIC and AGS Users’ Meeting pQCD Uncertainty (I) E-loss Mechanisms Initial Spectra S Wicks, et al., NPA784:426-442,2007 N Armesto, et al., Phys.Lett.B637:362-366,2006 S Wicks, Ph. D. Thesis 2009 RHIC and AGS Users’ Meeting

2009 RHIC and AGS Users’ Meeting pQCD Uncertainty (II) kT int. cutoff (UV) mg/IR kT cutoff B Cole and WH M Djordjevic, 0903.4591 B Cole and WH, not-yet-published 2009 RHIC and AGS Users’ Meeting

2009 RHIC and AGS Users’ Meeting Initial State Effects Cronin for e-? Coal. + K P.B. Gossiaux, QM09; P.B. Gossiaux, R. Bierkandt, J. Aichelin, arXiv:0901.0946 2009 RHIC and AGS Users’ Meeting

Out-of-Medium Hadronization Effects Add’l Channels Coalescence R Rapp and H van Hees, arXiv:0903.1096 H. van Hees, M. Mannarelli, V. Greco, and R. Rapp, Phys.Rev.Lett.100:192301,2008 2009 RHIC and AGS Users’ Meeting

In-Medium Hadronization Effects Coll. Diss. In-medium Frag. A Adil, I Vitev, Phys.Lett.B649:139-146,2007 A Adil and I Vitev, Phys.Lett.B649:139-146,2007 2009 RHIC and AGS Users’ Meeting

2009 RHIC and AGS Users’ Meeting AdS/CFT 2009 RHIC and AGS Users’ Meeting

Motivation for High-pT AdS Why study AdS E-loss models? Many calculations vastly simpler Complicated in unusual ways Data difficult to reconcile with pQCD pQCD quasiparticle picture leads to dominant q ~ m ~ .5 GeV mom. transfers => Nonperturbatively large as Use data to learn about E-loss mechanism, plasma properties Domains of self-consistency crucial for understanding 2009 RHIC and AGS Users’ Meeting

AdS/CFT Energy Loss Models I Langevin Diffusion Collisional energy loss for heavy quarks Restricted to low pT pQCD vs. AdS/CFT computation of D, the diffusion coefficient ASW/LRW model Radiative energy loss model for all parton species pQCD vs. AdS/CFT computation of Debate over its predicted magnitude Moore and Teaney, Phys.Rev.C71:064904,2005 Casalderrey-Solana and Teaney, Phys.Rev.D74:085012,2006; JHEP 0704:039,2007 BDMPS, Nucl.Phys.B484:265-282,1997 Armesto, Salgado, and Wiedemann, Phys. Rev. D69 (2004) 114003 Liu, Ragagopal, Wiedemann, PRL 97:182301,2006; JHEP 0703:066,2007 2009 RHIC and AGS Users’ Meeting

AdS/CFT Energy Loss Models II String Drag calculations: Embed string rep. quark/gluon in AdS geom. Includes all E-loss modes (difficult to interpret) Gluons and light quarks Empty space HQ calculation Previous HQ: thermalized QGP plasma, temp. T HQ in Shock: hot and cold nuclear matter Gubser, Gulotta, Pufu, Rocha, JHEP 0810:052, 2008 Chesler, Jensen, Karch, Yaffe, arXiv:0810.1985 [hep-th] Kharzeev, arXiv:0806.0358 [hep-ph] Gubser, Phys.Rev.D74:126005,2006 Herzog, Karch, Kovtun, Kozcaz, Yaffe, JHEP 0607:013, 2006 WH and Y Kovchegov, arXiv:0904.2536 2009 RHIC and AGS Users’ Meeting

2009 RHIC and AGS Users’ Meeting AdS Thermal Drag P Chesler, Quark Matter 2009 AdS/CFT Drag: dpT/dt ~ -(T2/Mq) pT WH, Ph. D. Thesis 2009 RHIC and AGS Users’ Meeting

2009 RHIC and AGS Users’ Meeting Shocking Loss HQ Drag in Hot and Cold nuclear matter Embedded String in Shock Q vshock x z Before After Recall for BH: Shock gives exactly the same drag as BH for L = p T 2009 RHIC and AGS Users’ Meeting

Future RHIC Measurements In-Medium Frag WH, J.Phys.G35:044025,2008 2009 RHIC and AGS Users’ Meeting

2009 RHIC and AGS Users’ Meeting Hard to Beat PHENIX, Phys. Rev. Lett. 98, 172301 (2007) S S Gubser, Quark Matter 2009 2009 RHIC and AGS Users’ Meeting

2009 RHIC and AGS Users’ Meeting pQCD Again 2009 RHIC and AGS Users’ Meeting

pQCD as Consistent Picture? v2 Sensitivity to IC A Drees, H Feng, J Jia, Phys.Rev.C71:034909,2005 2009 RHIC and AGS Users’ Meeting

2009 RHIC and AGS Users’ Meeting High e and pQCD h/s? T Hirano, et al., Phys.Lett.B636:299-304,2006 2009 RHIC and AGS Users’ Meeting

pQCD p and e- Consistency? Coll. fluctuations Dyn. scat. centers M Djordjevic, QM09; M Djordjevic and U Heinz, PRL101:022302,2008 S Wicks, Ph. D. Thesis 2009 RHIC and AGS Users’ Meeting

Conclusions and Outlook Exciting years ahead! Initial state effects Higher momenta Reduce hadronization effects Individual c and b contributions Disambiguate E-loss mechanisms HQ correlations Disambiguate E redistribution mechanisms Rehabilitation for pQCD? 2009 RHIC and AGS Users’ Meeting

2009 RHIC and AGS Users’ Meeting Supplements 2009 RHIC and AGS Users’ Meeting

LHC RcAA(pT)/RbAA(pT) Prediction Individual c and b RAA(pT) predictions: WH and M. Gyulassy, Phys. Lett. B 666, 320 (2008) WH and M. Gyulassy, Phys. Lett. B 666, 320 (2008) 2009 RHIC and AGS Users’ Meeting

2009 RHIC and AGS Users’ Meeting S Wicks, WH, M Djordjevic, and M Gyulassy, Nucl.Phys.A784:426-442,2007 2009 RHIC and AGS Users’ Meeting

2009 RHIC and AGS Users’ Meeting

Energy Loss Comparison D7 Probe Brane t z = 0 x v AdS/CFT Drag: dpT/dt ~ -(T2/Mq) pT Q, m zm = l1/2/2pm 3+1D Brane Boundary D3 Black Brane (horizon) zh = 1/pT Black Hole z = ¥ Similar to Bethe-Heitler dpT/dt ~ -(T3/Mq2) pT Very different from LPM dpT/dt ~ -LT3 log(pT/Mq) 2009 RHIC and AGS Users’ Meeting

2009 RHIC and AGS Users’ Meeting New Geometries Constant T Thermal Black Brane Shock Geometries Nucleus as Shock J Friess, et al., PRD75:106003, 2007 DIS Embedded String in Shock Before After Albacete, Kovchegov, Taliotis, JHEP 0807, 074 (2008) Q vshock x z vshock x z Q Bjorken-Expanding Medium 2009 RHIC and AGS Users’ Meeting

2009 RHIC and AGS Users’ Meeting