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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
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arXiv:0809.2869[hep-ph]
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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!!!
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RHIC physics
Quark Gluon Plasma
-Brookhaven-Started in year 2000-Collides Au
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AdS/CFT correspondence
Classical gravity limit
NN = 4 Super-Yang-Mills theory in 4d with SU(NC)
Maldacena (1997), Gubser, Klebanov,Polyakov; Witten (1998)
YM observables at infinite NC and infinite coupling can be computed using classical gravity
A string theory in 5d AdS
Finite temperature
Large NC and strong coupling limit
Black hole in AdS5
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Moving ‘quarks’ using AdS/CFT
AdS5 CFT
Massive particle
Endpoint of an open
string on the boundary
0
A heavy quark in the strongly coupled plasma
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Drag force from gauge – string duality
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Black hole
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The metric of AdS_5 in the presence of a black hole
Ansatz for rotating string
Nambu-Goto action
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The lagrangian takes the form
And the equations of motion
The constant of motion
One can obtain
One special point on the spiralling string
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Numerical solution of e.o.m/ Spiralling string
u_c
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Energy loss of rotating quarka) Linear drag
b) Vacuum radiation
Linear drag
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a) Linear drag
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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/0305196
sin( )2
a v av av
vacuum radiation
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b) Vacuum radiation
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Crossover between drag force-dominated regime and acceleration-dominated regime
32 4(1 )T v
32 4(1 )T v Crossover
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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.
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Expect many more chapters to be written for the marriage between string theory and physics of QCD in extreme conditions.
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متشکرم
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