High-Q^2 neutral current cross sections in e^+p deep inelastic scattering at sqrt{s}=318 GeV

TL;DR

This paper reports measurements of e^+p neutral current deep inelastic scattering cross sections at high Q^2, confirming Standard Model predictions and observing Z-boson exchange effects at very high momentum transfers.

Contribution

First detailed measurement of neutral current cross sections at sqrt{s}=318 GeV covering a wide Q^2 range, including Z-boson exchange effects, and combined with previous data to extract structure functions.

Findings

Cross sections measured up to Q^2=30000 GeV^2.

Observation of Z-boson exchange effects at Q^2 > 10000 GeV^2.

Results agree with Standard Model predictions.

Abstract

Cross sections for e^+p neutral current deep inelastic scattering have been measured at a centre-of-mass energy of sqrt{s}=318 GeV with the ZEUS detector at HERA using an integrated luminosity of 63.2 pb^-1. The double-differential cross section, d^2sigma/dxdQ^2, is presented for 200 GeV^2 < Q^2 < 30000 GeV^2 and for 0.005 < x < 0.65. The single-differential cross-sections dsigma/dQ^2, dsigma/dx and dsigma/dy are presented for Q^2 > 200 GeV^2. The effect of Z-boson exchange is seen in dsigma/dx measured for Q^2 > 10000 GeV^2. The data presented here were combined with ZEUS e^+p neutral current data taken at sqrt{s}=300 GeV and the structure function F_2^{em} was extracted. All results agree well with the predictions of the Standard Model.