Deep Inelastic Scattering from the AdS/CFT correspondence
Abstract
We calculate [J.L. Albacete, Y.V. Kovchegov, and A. Taliotis, JHEP07, 074 (2008), 0806.1484] the cross section of an ultra relativistic nucleus scattering on a qq OverBar pair at large coupling in N=4 SUSY gauge theory. We study the problem in the context of the AdS/CFT correspondence [J.M. Maldacena, Adv. Theor. Math. Phys. 2 (1998) 231252]. The nucleus is modeled as a gravitational shockwave in an AdS_{5} background moving along the light cone. The dipole (qq OverBar) is represented by a Wilson loop moving in the opposite direction. Due to the correspondence, calculating the scattering amplitude of the Wilson loop with the nucleus, reduces to calculating the extreme value of the NambuGoto action for an open string. Its two end points are attached to the qq OverBar respectively and it hangs in an AdS_{5} shockwave spacetime. Six solutions are found two of which are physically meaningful. Both solutions predict that the saturation scale Q_{} at high enough energies becomes energy independent; in particular it behaves as Q_{}∝A^{1} where A is the atomic number. One solution predicts pomeron intercept α_{}=2 and agrees with [R.C. Brower, J. Polchinski, M.J. Strassler, and C.I. Tan, JHEP12 (2007) 005, [hepth/0603115 ]]. However, there is a parameter window of r (dipole size) and s (c.m. energy) where it violates the black disk limit. On the other hand, the other solution respects this limit and corresponds to pomeron intercept α_{}=1.5. We conjecture that this is the right value for gauge theories at strong coupling.
 Publication:

Nuclear Physics A
 Pub Date:
 November 2009
 DOI:
 10.1016/j.nuclphysa.2009.10.026
 arXiv:
 arXiv:0907.4204
 Bibcode:
 2009NuPhA.830..299T
 Keywords:

 AdS/CFT;
 Deep Inelastic Scattering (DIS);
 Saturation;
 Wilson loop;
 pomeron;
 High Energy Physics  Theory
 EPrint:
 4 pages, 3 figures  To appear in the conference proceedings for Quark Matter 2009, March 30  April 4, Knoxville, Tennessee