Accessing the Longitudinally Polarized Photon Content of the Proton

Abstract

We investigate the QED Compton process (QEDCS) in longitudinally polarized lepton-proton scattering both in the elastic and inelastic channels and show that the cross section can be expressed in terms of the polarized equivalent photon distribution of the proton. We provide the necessary kinematical constraints to extract the polarized photon content of the proton using this process at HERMES, COMPASS and eRHIC. We also discuss the suppression of the major background process coming from virtual Compton scattering. We point out that such an experiment can give valuable information on $g_1(x_B,Q^2)$ in the small $x_B$, broad $Q^2$ region at the future polarized collider eRHIC and especially in the lower $Q^2$, medium $x_B$ region in fixed target experiments.

Version to appear in PRD

References in corpus (7)

• Generalized Parton Distributions
• Measurement of the Proton Spin Structure Function $g_1(x,Q^2)$ for $Q^2$ from 0.15 to 1.6 GeV${}^2$ with CLAS
• Evidence for Quark-Hadron Duality in the Proton Spin Asymmetry $A_1$
• Measurement of Inclusive Spin Structure Functions of the Deuteron
• Manifestly Covariant Analysis of the QED Compton Process in $ep\to e\gamma p$ and $ep\to e\gamma X$
• Delineating the polarized and unpolarized photon distributions of the nucleon in eN collisions
• On the Investigation of the Proton Structure Using QED Compton Events in ep Scattering

Cited by in corpus (3)

• Light Sea Fermions in Electron-Proton and Muon-Proton Interactions
• Testing the Equivalent Photon Approximation of the Proton in the Process $ep\to \nu WX$
• Probing the polarized photon content of the proton in $ep$ collisions at the EIC