Distribution amplitudes of light diquarks

TL;DR

This paper calculates the distribution amplitudes of light diquarks, revealing their narrower and taller profiles compared to mesons, which impacts our understanding of baryon structure and quark momentum distribution.

Contribution

It provides the first calculation of leading-twist two-parton distribution amplitudes for light-quark scalar and pseudovector diquarks using continuum bound-state equations.

Findings

Diquark distribution amplitudes are narrower and taller than mesonic asymptotic profiles.

Valence quasiparticles in diquarks are less likely to carry large momentum fractions.

Results may influence models of baryon distribution functions and internal quark momentum sharing.

Abstract

Accumulating evidence indicates that soft quark+quark (diquark) correlations play an important role in the structure and interactions of hadrons constituted from three or more valence-quarks; so, it is worth developing insights into diquark structure. Using a leading-order truncation of those equations needed to solve continuum two-valence-body bound-state problems, the leading-twist two-parton distribution amplitudes (DAs) of light-quark scalar and pseudovector diquarks are calculated. The diquark DAs are narrower and taller than the asymptotic profile that characterises mesons. Consequently, the valence quasiparticles in a diquark are less likely to carry a large light-front fraction of the system's total momentum than those in a meson. These features may both influence the form of baryon DAs and be transmitted to diquark distribution functions (DFs), in which case their impact will be felt, e.g. in the proton's $u$ and $d$ valence-quark DFs.