Distribution functions of \(\varLambda \) and \(\varSigma ^0\) baryons

Abstract

Treating baryons as quark + interacting-diquark bound states, a symmetry-preserving formulation of a vector\(\,\times \,\)vector contact interaction (SCI) is used to deliver an extensive, coherent set of predictions for \(\varLambda , \varSigma ^0\) baryon unpolarised and polarised distribution functions (DFs) – valence, glue, and four-flavour separated sea – and compare them with those of a like-structured nucleon. \(\varLambda , \varSigma ^0\) baryons are strangeness negative-one isospin partners within the SU(3)-flavour baryon octet. This makes such structural comparisons significant. The study reveals impacts of diquark correlations and SU(3)-flavour symmetry breaking on \(\varLambda \), \(\varSigma ^0\) structure functions, some of which are significant. For instance, were it not for the presence of axialvector diquarks in the \(\varSigma ^0\) at the hadron scale, the s quark could carry none of the \(\varSigma ^0\) spin. The discussion canvasses issues that include helicity retention in hard scattering processes; the sign and size of polarised gluon DFs; and the origin and decomposition of baryon spins. Interpreted judiciously, the SCI analysis delivers an insightful explanation of baryon structure as expressed in DFs.