Holographic pomeron: Saturation and DIS

We briefly review the approach to dipole-dipole scattering in holographic QCD developed in G. Basar et al., Phys. Rev. D 85, 105005 (2012), based on a stringy Schwinger mechanism. The pomeron emerges through the exchange of closed strings between the dipoles and yields Regge behavior for the elastic amplitude. We calculate curvature corrections to this amplitude in both a conformal and confining background, identifying the holographic direction with the virtuality of the dipoles. The wee-dipole density is related to the string tachyon diffusion in both virtuality and the transverse directions. We give an explicit derivation of the dipole saturation momentum both in the conformal and confining background. Our holographic result for the dipole-dipole cross section and the wee-dipole density in the conformal limit are shown to be identical in form to the BFKL pomeron result when the noncritical string transverse dimension is D-perpendicular to = 3. The total dipole-dipole cross section is compared to DIS data from HERA. DOI: 10.1103/PhysRevD.87.075023