Measurement of Leading Neutron Production in Deep-Inelastic Scattering at HERA

TL;DR

This paper measures the production of leading neutrons in deep-inelastic scattering at HERA, providing insights into the pion structure function and the mechanisms behind neutron production.

Contribution

It presents the first detailed measurement of leading neutron production cross sections and structure functions in a broad kinematic range at HERA, constraining pion exchange models.

Findings

Leading neutron production cross sections measured across various Q^2, x, and x_L.

Data supports pion exchange as a dominant mechanism for leading neutron production.

Results constrain the shape of the pion structure function.

Abstract

The production of leading neutrons, where the neutron carries a large fraction x_L of the incoming proton's longitudinal momentum, is studied in deep-inelastic positron-proton scattering at HERA. The data were taken with the H1 detector in the years 2006 and 2007 and correspond to an integrated luminosity of 122 pb^{-1}. The semi-inclusive cross section is measured in the phase space defined by the photon virtuality 6 < Q^2 < 100 GeV^2, Bjorken scaling variable 1.5x10^{-4} < x < 3x10^{-2}, longitudinal momentum fraction 0.32 < x_L < 0.95 and neutron transverse momentum p_T < 0.2 GeV. The leading neutron structure function, F_2^{LN(3)}(Q^2,x,x_L), and the fraction of deep-inelastic scattering events containing a leading neutron are studied as a function of Q^2, x and x_L. Assuming that the pion exchange mechanism dominates leading neutron production, the data provide constraints on the shape of the pion structure function.