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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

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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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