Sea quark transverse momentum distributions and dynamical chiral symmetry breaking

TL;DR

This paper explores the intrinsic transverse momentum distributions of valence and sea quarks in the nucleon, highlighting their different origins and implications for QCD modeling, with potential experimental observability.

Contribution

It provides new insights into the non-perturbative origins of sea quark transverse momentum distributions and their impact on QCD evolution models.

Findings

Valence quark p_T distributions governed by nucleon size (~0.2 GeV)

Sea quark p_T distributions extend up to ~0.6 GeV due to chiral symmetry breaking

Qualitative differences could be observed experimentally in hadron and dilepton production

Abstract

Recent theoretical studies have provided new insight into the intrinsic transverse momentum distributions of valence and sea quarks in the nucleon at a low scale. The valence quark transverse momentum distributions (q - qbar) are governed by the nucleon's inverse hadronic size R^{-1} ~ 0.2 GeV and drop steeply at large p_T. The sea quark distributions (qbar) are in large part generated by non-perturbative chiral-symmetry-breaking interactions and extend up to the scale rho^{-1} ~ 0.6 GeV. These findings have many implications for modeling the initial conditions of perturbative QCD evolution of TMD distributions (starting scale, shape of p_T distributions, coordinate-space correlation functions). The qualitative difference between valence and sea quark intrinsic p_T distributions could be observed experimentally, by comparing the transverse momentum distributions of selected hadrons in semi-inclusive deep-inelastic scattering, or those of dileptons produced in pp and pbar-p scattering.