Rapidity loss, spin and angular asymmetries in scattering of a quark from color field of a proton (nucleus)

TL;DR

This paper calculates quark scattering helicity amplitudes from a proton or nucleus, revealing spin asymmetries and rapidity loss, and discusses their implications for angular asymmetries in high-energy collisions.

Contribution

It introduces a formalism for calculating helicity amplitudes in quark scattering from gluons, highlighting effects of large $x$ gluons on spin asymmetries and rapidity loss.

Findings

Non-zero spin asymmetry at intermediate $p_t$ from large $x$ gluons

Rapidity loss of the projectile quark due to scattering

Potential generation of angular asymmetries in particle production

Abstract

We calculate the helicity amplitudes for scattering of a quark from both large and small $x$ gluons of a target proton or nucleus using spinor helicity formalism. We show that scattering from large $x$ gluons of the target results in non-zero spin asymmetry at intermediate $p_t$ as well as rapidity loss of the projectile quark. We comment on how this can also generate angular asymmetries in particle production in high energy collisions.