Measurement of neutral current cross sections at high Bjorken-x with the ZEUS detector at HERA

TL;DR

This paper presents a novel measurement of neutral current cross sections at very high Bjorken-x using the ZEUS detector at HERA, revealing potential deviations from existing parton density function predictions at the highest x values.

Contribution

A new method is introduced to measure neutral current cross sections at Bjorken-x close to one, extending the kinematic range of previous measurements.

Findings

Data tend to lie above predictions at the highest x bins.

Cross sections are measured for Q2 >= 648 GeV^2.

Results suggest possible discrepancies with current parton density functions.

Abstract

A new method is employed to measure the neutral current cross section up to Bjorken-x values of one with the ZEUS detector at HERA using an integrated luminosity of 65.1 pb-1 for e+p collisions and 16.7 pb-1 for e-p collisions at sqrt{s}=318 GeV and 38.6 pb-1 for e+p collisions at sqrt{s}=300 GeV. Cross sections have been extracted for Q2 >= 648 GeV2 and are compared to predictions using different parton density functions. For the highest x bins, the data have a tendency to lie above the expectations using recent parton density function parametrizations.