Polarized Parton Densities and Processes

TL;DR

This paper reviews the theoretical and phenomenological aspects of polarized deep inelastic scattering, discussing spin-dependent parton densities, QCD calculations, and potential measurements at future polarized colliders.

Contribution

It introduces the framework for polarized parton densities and discusses recent results and technical challenges in spin-dependent QCD calculations, with a focus on future experimental prospects.

Findings

Discussion of spin-dependent parton densities for protons and photons

Recent results on jet and heavy quark production in polarized processes

Analysis of technical issues like gamma_5 prescription in NLO QCD calculations

Abstract

The main goals of `spin physics' are recalled, and some theoretical and phenomenological aspects of longitudinally polarized deep inelastic scattering and other hard processes are reviewed. The spin dependent parton densities of protons and photons and polarized fragmentation functions are introduced, and the relevant theoretical framework in next-to-leading order QCD is briefly summarized. Technical complications typical for spin dependent calculations beyond the leading order of QCD, like a consistent gamma_5 prescription, are sketched, and some recent results for jet and heavy quark production are discussed. Special emphasis is put on conceivable measurements at a future polarized upgrade of the HERA collider which is currently under consideration.