Measurement of high-Q2 deep inelastic scattering cross sections with longitudinally polarised positron beams at HERA

TL;DR

This paper reports the first measurements of deep inelastic scattering cross sections with longitudinally polarised positron beams at HERA, comparing results with Standard Model predictions at high Q^2.

Contribution

It provides novel measurements of neutral and charged current cross sections with polarised positron beams, testing Standard Model predictions at high momentum transfer.

Findings

Cross sections are consistent with Standard Model expectations.

Measured cross sections vary with positron beam polarisation.

Results extend understanding of electroweak interactions at high energies.

Abstract

The first measurements of the cross sections for neutral and charged current deep inelastic scattering in e+p collisions with longitudinally polarised positron beams are presented. The total cross section for e+p charged current deep inelastic scattering is presented at positive and negative values of positron beam longitudinal polarisation for an integrated luminosity of 37.0 pb^-1 H1 data and 30.5 pb^-1 ZEUS data collected in 2003 and 2004 at a centre-of-mass energy of 319 GeV. In addition, the ZEUS collaboration measured the single differential cross sections for charged and neutral current deep inelastic scattering in the kinematic region Q^2>200 GeV^2. The measured cross sections are compared with the predictions of the Standard Model. The H1 collaboration extrapolate the cross section to a fully left handed positron beam and find it to be consistent with the Standard Model expectation.