Observation of Events with an Energetic Forward Neutron in Deep Inelastic Scattering at HERA

TL;DR

This paper reports the observation of high-energy neutrons produced at small angles in deep inelastic scattering events at HERA, revealing a consistent fraction of such events across various kinematic ranges.

Contribution

First observation of energetic forward neutrons in deep inelastic scattering at HERA, showing a constant production fraction across different Bjorken x and Q^2 values.

Findings

High-energy neutrons observed at small angles in DIS events.

The neutron production fraction remains constant across specified kinematic ranges.

Results suggest a universal mechanism for forward neutron production in DIS.

Abstract

In deep inelastic neutral current scattering of positrons and protons at the center of mass energy of 300 GeV, we observe, with the ZEUS detector, events with a high energy neutron produced at very small scattering angles with respect to the proton direction. The events constitute a fixed fraction of the deep inelastic, neutral current event sample independent of Bjorken $x$ and $Q^2$ in the range $ 3 \cdot 10^{-4} < \xbj < 6\cdot 10^{-3}$ and $10 < Q^2 <100$~GeV$^2$.