Intrinsic transverse momentum and parton correlations from dynamical chiral symmetry breaking

TL;DR

This paper investigates how dynamical chiral symmetry breaking in QCD influences the intrinsic transverse momentum and correlations of partons within the nucleon, using a chiral quark-soliton model to connect low-energy dynamics with high-momentum parton distributions.

Contribution

It introduces a model-based analysis of parton transverse momentum distributions and correlations arising from chiral symmetry breaking, highlighting model-independent features and their implications for high-energy scattering experiments.

Findings

Valence quark p_T distribution is Gaussian and localized around R^{-2}.

Sea quark distribution exhibits a power-like tail up to the chiral scale.

Short-range correlations between sea quarks lead to high-momentum tails in distributions.

Abstract

The dynamical breaking of chiral symmetry in QCD is caused by nonperturbative interactions on a scale rho ~ 0.3 fm, much smaller than the hadronic size R ~ 1 fm. These short-distance interactions influence the intrinsic transverse momentum distributions of partons and their correlations at a low normalization point. We study this phenomenon in an effective description of low-energy dynamics based on chiral constituent quark degrees of freedom, which refers to the large-N_c limit of QCD. The nucleon is obtained as a system of constituent quarks and antiquarks moving in a self-consistent classical chiral field (chiral quark-soliton model). The calculated distributions of constituent quarks/antiquarks are matched with QCD partons at the scale rho^{-2}. The p_T distribution of valence quarks is localized at p_T^2 ~ R^{-2} and roughly of Gaussian shape. The sea quark distribution exhibits a would-be power-like tail ~1/p_T^2 extending up to the chiral symmetry-breaking scale. Such behavior is seen in the flavor-singlet unpolarized and nonsinglet polarized sea. The high-momentum tails are the result of short-range correlations between sea quarks in the nucleon's light-cone wave function, analogous to NN correlations in nuclei. The nucleon wave function contains correlated pairs of transverse size rho << R with sigma- and pi-like quantum numbers, whose internal wave functions become identical at p_T^2 ~ rho^{-2} (restoration of chiral symmetry). These features are model-independent and represent an effect of dynamical chiral symmetry breaking on the nucleon's partonic structure. Our results have numerous implications for the P_T distributions of particles produced in hard scattering processes. The nonperturbative parton correlations predicted here could be observed in particle correlations between the current and target fragmentation regions of DIS.