Generalized Parton Distributions of the Photon with Helicity Flip

Abstract

We present a calculation of the generalized parton distributions (GPDs) of the photon when the helicity of the initial photon is different from the final photon. We calculate the GPDs using overlaps of photon light-front wave functions (LFWFs) at leading order in electromagnetic coupling $\alpha$ and zeroth order in the strong coupling ${\alpha }_s$, when the momentum transfer is purely in the transverse direction. These involve a contribution of orbital angular momentum of two units in the LFWFs. We express these GPDs in the impact parameter space.

Comments: Minor changes, version to appear in Phys. Lett. B