High Q2 Structure Functions at HERA

TL;DR

This paper reports on recent HERA measurements of electroweak cross sections with polarized lepton beams, confirming Standard Model predictions and constraining quark couplings to the Z boson through combined data analysis.

Contribution

It provides new measurements of electroweak cross sections with polarized beams and improved parton density functions, along with combined analysis constraining quark-Z couplings.

Findings

Parity violation in neutral current cross sections confirmed

No evidence for right-handed charged currents

Constraints on quark-Z couplings improved

Abstract

The latest results of H1 and ZEUS on the electroweak cross sections using polarised lepton beams are presented with the improvements in the parton density functions that result from them. The asymmetry of the neutral current cross sections between e-p and e+p was measured and shows parity violation in agreement with the Standard Model. The dependence of the charged current cross section on the beam polarisation has been obtained and its extrapolation to full polarisation implies the absence of right-handed charged currents. Constraints on the vector and axial vector couplings of the u and d quarks to the Z boson from a combined QCD and electroweak fit are shown and the results from the combination of H1 and ZEUS data are reviewed.