Electroweak Results from HERA

TL;DR

This paper reports on electroweak measurements from deep inelastic ep scattering at HERA, including structure functions, couplings, and searches for new physics at high momentum transfer, confirming Standard Model predictions.

Contribution

It provides new measurements of electroweak parameters and constraints on physics beyond the Standard Model using high-Q^2 data from HERA.

Findings

Measured differential cross sections up to Q^2 of 50,000 GeV^2

Determined the structure function xF_3 and quark couplings to Z^0

Set limits on flavor-changing neutral currents and contact interactions

Abstract

Neutral and charged current deep inelastic ep scattering with longitudinally polarised lepton beams has been studied with the H1 and ZEUS detectors at HERA. The differential cross sections were measured in the range of four-momentum transfer squared, Q^2, up to 50'000 GeV^2, where electroweak effects become clearly visible. The measurements were used to determine the structure function xF_3 and to constrain vector and the axial-vector couplings of the light quarks to the Z^0 boson. The polarisation dependence of the charged current total cross section was also measured. Limits on flavour changing neutral current processes were computed from the search for single-top production. The elastic Z^0 production cross section was measured to be in agreement with the SM prediction. Limits on new physics phenomena at high Q^2 were also derived within the general framework of four-fermion eeqq contact interactions.