Transverse momentum of partons: from low to high pT

TL;DR

This paper explores the theoretical relationship between intrinsic transverse momentum and perturbative radiation in describing parton transverse-momentum spectra, focusing on semi-inclusive deep inelastic scattering and its implications for phenomenology.

Contribution

It clarifies the connection between different descriptions of parton transverse momentum and discusses the theoretical issues involved in defining transverse-momentum dependent distributions.

Findings

Analyzes the relation between intrinsic and radiative pT descriptions.

Highlights the importance of proper TMD definitions for phenomenology.

Provides insights into angular distributions in semi-inclusive DIS.

Abstract

Transverse-momentum spectra in hard processes are typically described either in terms of intrinsic transverse momentum of partons, or in terms of perturbative radiation. The relation between these descriptions is discussed for the example of semi-inclusive deep inelastic scattering, with special focus on the angular distribution of the observed hadron. This involves nontrivial theoretical issues, such as the proper definition of transverse-momentum dependent parton distributions, and has practical consequences for the description of pT spectra in phenomenology.