Measurement of high-Q^2 e^-p neutral current cross sections at HERA and the extraction of xF_3

TL;DR

This work delivers a comprehensive measurement of high-Q^2 neutral-current e^-p DIS cross sections at HERA, providing double- and single-differential results and a reduced cross section across 185<Q^2<50 000 GeV^2. By combining with e^+p data, the parity-violating structure function xF_3 is extracted, and the corresponding xG_3 is compared with BCDMS results, extending the x-range down to 0.05. The analysis employs detailed detector calibration, robust MC modeling (HERACLES+DJANGOH, ARIADNE/LEPTO, RAPGAP), and a DA-based kinematic reconstruction, with systematic uncertainties carefully separated into correlated and uncorrelated components. Overall, the measurements agree with Standard Model predictions across multiple PDF sets, affirming Z-boson exchange in space-like DIS and providing important constraints on electroweak PDFs and structure functions in this kinematic domain.

Abstract

Cross sections for e^-p neutral current deep inelastic scattering have been measured at a centre-of-mass energy of 318 GeV using an integrated luminosity of 15.9 pb^-1 collected with the ZEUS detector at HERA. Results on the double-differential cross-section d^2s/dxdQ^2 in the range 185 < Q^2 < 50000 GeV^2 and 0.0037 < x < 0.75, as well as the single-differential cross-sections ds/dQ^2, ds/dx and ds/dy for Q^2 > 200 GeV^2, are presented. To study the effect of Z-boson exchange, ds/dx has also been measured for Q^2 > 10000 GeV^2. The structure function xF_3 has been extracted by combining the e^-p results presented here with the recent ZEUS measurements of e^+p neutral current deep inelastic scattering. All results agree well with the predictions of the Standard Model.