Measurement of the Inclusive ep Scattering Cross Section at Low Q^2 and x at HERA

TL;DR

This paper reports precise measurements of the inclusive ep scattering cross section at low Q^2 and x at HERA, providing valuable data for understanding the transition from photoproduction to deep inelastic scattering.

Contribution

It presents new measurements at low Q^2 and x, combining data from dedicated runs and previous results, and extends the kinematic range using a novel reconstruction method.

Findings

Cross section measured with a few percent accuracy.

Data agree with theoretical models in the transition region.

Extended measurement to lower Q^2 and larger x.

Abstract

A measurement of the inclusive ep scattering cross section is presented in the region of low momentum transfers, 0.2 GeV^2 < Q^2 < 12 GeV^2, and low Bjorken x, 5x10^-6 < x < 0.02. The result is based on two data sets collected in dedicated runs by the H1 Collaboration at HERA at beam energies of 27.6 GeV and 920 GeV for positrons and protons, respectively. A combination with data previously published by H1 leads to a cross section measurement of a few percent accuracy. A kinematic reconstruction method exploiting radiative ep events extends the measurement to lower Q^2 and larger x. The data are compared with theoretical models which apply to the transition region from photoproduction to deep inelastic scattering.