Deeply Virtual Compton Scattering at HERA II

TL;DR

This paper reports a new measurement of elastic deeply virtual Compton scattering (DVCS) at HERA II, including the first beam charge asymmetry, which aligns well with QCD calculations and reveals interference effects between QCD and QED processes.

Contribution

It presents the first beam charge asymmetry measurement in DVCS at HERA, providing new insights into interference effects between QCD and QED processes.

Findings

QCD-based calculations describe the data well

First measurement of beam charge asymmetry in DVCS

Significant non-zero asymmetry indicating interference effects

Abstract

A new measurement is presented of elastic deeply virtual Compton scattering (DVCS) based on data taken by the H1 detector during the complete HERA II period. The data are well described by QCD based calculations. For the first time, a beam charge asymmetry is obtained in a colliding mode, using data recorded in $e^-p$ and $e^+p$. A significant non zero value is measured, related to the interference of QCD and QED processes, namely the DVCS and Bethe-Heitler reactions.