Measurement of the inclusive ep scattering cross section at low Q 2 and x at HERA

Abstract

A measurement of the inclusive ep scattering cross section is presented in the region of low momentum transfers, 0.2∈GeV2 ≤Q 2≤12∈GeV2, and low Bjorken x, 5.10 -6x≤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. © 2009 Springer-Verlag / Società Italiana di Fisica.