Azimuthal anisotropy of direct photons

Abstract

The electromagnetic bremsstrahlung produced by a quark interacting with nucleons or nuclei is azimuthally asymmetric. In the light-cone dipole approach this effect is related to the orientation dependent dipole cross section. Such a radiation anisotropy is expected to contribute to the azimuthal asymmetry of direct photons in pA and AA collisions, as well as in DIS and in the production of dileptons.

Comments: Equations (23), (26) and the figures are corrected, references added. The version to appear in Phys. Rev. D