O(alpha_s) spin effects in e+ e- -> q qbar (g)

TL;DR

This paper analyzes first-order QCD spin effects in electron-positron annihilation into quark-antiquark pairs with gluon emission, focusing on polarization and spin correlations, including residual mass effects as quark mass approaches zero.

Contribution

It provides a detailed analysis of O(alpha_s) spin effects, highlighting residual mass effects and their universal helicity contributions in e+ e- -> q qbar (g).

Findings

Identification of residual mass effects in the massless limit.

Universal helicity flip and non-flip contributions.

Insights into spin correlations in QCD processes.

Abstract

We discuss O(alpha_s) spin effects in e+ e- -> q qbar (g) for the polarization of single quarks and for spin-spin correlations of the final state quarks. Particular attention is paid to residual mass effects in the limit m_q -> 0 which are described in terms of universal helicity flip and helicity non-flip contributions.