Measurement of the energy dependence of the total photon-proton cross section at HERA

TL;DR

This paper measures how the total photon-proton cross section varies with energy at HERA, providing the first high-W W dependence measurement from a single experiment, and finds it follows a power-law with epsilon approximately 0.111.

Contribution

It presents the first measurement of the W dependence of sigma-tot from a single experiment at high energies, using ep scattering data at HERA.

Findings

Determined sigma-tot at three W values between 194 and 296 GeV.

Parameterization of sigma-tot as proportional to W^(2 epsilon).

Measured epsilon as 0.111 +/- 0.009 (stat.) +/- 0.036 (syst.).

Abstract

The energy dependence of the photon-proton total cross section, sigma-tot, was determined from ep scattering data collected with the ZEUS detector at HERA at three values of the center-of-mass energy, W, of the gamma-p system in the range 194<W<296 GeV. This is the first determination of the W dependence of sigma-tot from a single experiment at high W. Parameterizing sigma-tot proportional to W^(2 epsilon), epsilon = 0.111 +/- 0.009 (stat.) +/- 0.036 (syst.) was obtained.