Leading neutrons from polarized pp collisions

TL;DR

This paper calculates the cross section and spin asymmetry for neutron production in polarized proton-proton collisions, highlighting the role of absorptive corrections and identifying limitations in explaining recent experimental results.

Contribution

It introduces a calculation of the single-spin azimuthal asymmetry incorporating absorptive corrections, revealing their impact on neutron production in polarized pp collisions.

Findings

Absorptive corrections induce a significant spin asymmetry.

The calculated asymmetry does not match the small asymmetry observed at RHIC.

The mechanism explains some asymmetry but not the very small |t| asymmetry in experiments.

Abstract

We calculate the cross section and single-spin azimuthal asymmetry, A_n(t) for inclusive neutron production in pp collisions at forward rapidities relative to the polarized proton. Absorptive corrections to the pion pole generate a relative phase between the spin-flip and non-flip amplitudes, which leads to an appreciable spin asymmetry. However, the asymmetry observed recently in the PHENIX experiment at RHIC at very small |t|~0.01GeV^2 cannot be explained by this mechanism.