1 Energy Loss of a Rotating Quark from Gauge-String Duality K. Bitaghsir Fadafan Shahrood U. of Technology First IPM meeting on LHC physics April 20-24, 2009 Isfahan, IRAN

2 arXiv: [hep-ph]

3 1-Standard model predicts QCD deconfined phase transition 2-Cosmology  Quark-Hadron phase transition at the early universe Why Quark Gluon Plasma is important? Now we can study the QGP in the lab!!!

4 RHIC physics Quark Gluon Plasma -Brookhaven -Started in year Collides Au

5 AdS/CFT correspondence Classical gravity limit N N = 4 Super-Yang-Mills theory in 4d with SU(N C ) Maldacena (1997), Gubser, Klebanov,Polyakov; Witten (1998) YM observables at infinite N C and infinite coupling can be computed using classical gravity A string theory in 5d AdS Finite temperature Large N C and strong coupling limit Black hole in AdS 5

6

7 Moving ‘quarks’ using AdS/CFT AdS 5 CFT Massive particle Endpoint of an open string on the boundary 0 A heavy quark in the strongly coupled plasma

8 Drag force from gauge – string duality

9 Black hole

10 The metric of AdS_5 in the presence of a black hole Ansatz for rotating string Nambu-Goto action

11 The lagrangian takes the form And the equations of motion The constant of motion One can obtain One special point on the spiralling string

12 Numerical solution of e.o.m/ Spiralling string u_c

13 Energy loss of rotating quark a) Linear drag b) Vacuum radiation Linear drag

14 a) Linear drag

15 Circular motion: b) Vacuum radiation Mikhailov has derived an elegant and general result for radiation of an accelerating quark in N=4 SYM theory in vacuum. arXiv:hep-th/ vacuum radiation

16 b) Vacuum radiation

17 Crossover between drag force-dominated regime and acceleration-dominated regime Crossover

18 Conclusions and summery We see the significant advantage offered by the analysis of the rotating quark. The energy loss in the acceleration-dominated regime is as if the quark is in vacuum. AdS/CFT provides powerful tools to understand dynamics of strong coupled gauge theories.

19 Expect many more chapters to be written for the marriage between string theory and physics of QCD in extreme conditions.

20 متشکرم

21