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 α and zeroth order in the strong coupling α 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.

Nucleon axial form factor from generalized parton distributions

“…In this work, we study the nucleon axial form factor and polarized GPDs, given the fact that they are connected via sum rules. Although, there are various models [56][57][58][59][60][61] and parameterizations [62][63][64] for GPDs, we use a practical ansatz suggested by Diehl [30][31][32] which relates the predetermined (polarized) PDFs as input to (polarized) GPDs. An important advantage of this ansatz is that it has a few free parameters to be fixed by analyzing experimental data.…”

The GPDs of the photon

“…. Using the overlap formula in terms of the LFWFs, the helicity flip photon GPD can be calculated and has the form [11]…”

Basis light-front quantization approach to photon

“…[1], where the authors considered the deeply virtual Compton scattering (DVCS), γ * γ → γγ, assuming the nearly real photon as a photon target. Later, the photon GPDs have been studied using the light-front wave function of the photon obtained analytically using perturbation theory [18][19][20]. The analytic properties of DVCS amplitudes and related sum rules of the photon GPDs have been investigated in Ref.…”