Axial $N\to \Delta(1232)$ and $N \to N^{\star}(1440)$ transition form factors

Abstract

We calculate the axial $N\to \Delta(1232)$ and $N\to N^{\star}(1440)$ transition form factors in a chiral constituent quark model. As required by the partial conservation of axial current ($PCAC$) condition, we include one- and two-body axial exchange currents. For the axial $N\to \Delta(1232)$ form factors we compare with previous quark model calculations that use only one-body axial currents, and with experimental analyses. The paper provides the first calculation of all weak axial $N\to N^{\star}(1440)$ form factors. Our main result is that exchange currents are very important for certain axial transition form factors. In addition to improving our understanding of nucleon structure, the present results are relevant for neutrino-nucleus scattering cross section predictions needed in the analysis of neutrino mixing experiments.