Contact interaction analysis of octet baryon axial-vector and pseudoscalar form factors

Octet baryon axial, induced pseudoscalar, and pseudoscalar form factors are computed using a symmetry-preserving treatment of a vector x vector contact interaction (SCI), thereby unifying them with an array of other baryon properties and analogous treatments of semileptonic decays of pseudoscalar mesons. The baryons are treated as quark-plus-interacting-diquark bound states, whose structure is obtained by solving a Poincare-covariant Faddeev equation. The approach is marked by algebraic simplicity and involves no free parameters, and, since it is symmetry preserving, all consequences of partial conservation of the axial current are manifest. It is found that SCI results are consistent with only small violations of SU(3)-flavor symmetry, an outcome which may be understood as a dynamical consequence of emergent hadron mass. The spin-flavor structure of the Poincare-covariant baryon wave functions is expressed in the presence of both flavor-antitriplet-scalar diquarks and flavor-sextet-axial-vector diquarks and plays a key role in determining all form factors. Considering neutral axial currents, SCI predictions for the flavor separation of octet baryon axial charges and, therefrom, values for the associated SU(3) singlet, triplet, and octet axial charges are obtained. The results indicate that, at the hadron scale zeta H, valence degrees of freedom carry roughly 50% of an octet baryon's total spin. Since there are no other degrees of freedom at zeta H, the remainder may be associated with quark + diquark orbital angular momentum.