Azimuthal Asymmetries in Hadronic Final States at HERA

TL;DR

This paper studies azimuthal asymmetries in hadron production at HERA, highlighting both known and polarization-induced asymmetries, and explores their potential to reveal time-reversal-odd effects.

Contribution

It provides a detailed analysis of azimuthal asymmetries, including polarization effects and the potential to measure time-reversal-odd asymmetries in deep inelastic scattering.

Findings

Identification of non-vanishing left-right asymmetry with polarized electrons

Quantitative estimates of azimuthal asymmetries at HERA

Discussion on the feasibility of measuring time-reversal-odd effects

Abstract

The distribution of hadrons produced in deeply inelastic electron-proton collisions depends on the azimuthal angle between lepton scattering plane and hadron production plane in the photon-proton centre-of-mass frame. In addition to the well known up-down asymmetry induced by the azimuthal dependence of the Born level subprocess, there is also a non-vanishing left-right asymmetry, provided the incoming electron is polarized. This asymmetry is time-reversal-odd and induced by absorptive corrections to the Born level process. We investigate the numerical magnitude of azimuthal asymmetries in semi-inclusive hadron production at HERA with particular emphasis on a possible determination of the time-reversal-odd asymmetry.