Suppressing the background process to QED Compton scatteringfor delineating the photon content of the proton

Abstract.

We investigate the QED Compton process (QEDCS) in $e p \rightarrow e \gamma p$ and $e p \rightarrow e \gamma X$, together with the major background coming from virtual Compton scattering (VCS), where the photon is emitted from the hadronic vertex. We suggest new kinematical constraints which suppress the VCS background and are furthermore suitable for the extraction of the equivalent photon content of the proton at the HERA collider. We show that the cross section, commonly expressed in terms of the proton structure functions, is reasonably well described by the equivalent photon approximation of the proton, also in the inelastic channel in the proposed kinematical region.