Pion axioproduction revisited

Abstract

In this work, we extend the analysis of the pion axioproduction, $aN\to \ddot{I}€N$, to include the impact of the Roper resonance $N^{\ast }(1440)$ together the previously studied $\hat{I}”(1232)$ resonance. Our theoretical framework is chiral perturbation theory with explicit resonance fields to account for their respective impacts. We find that the Roper resonance also leads to an enhancement of the cross section within its energy range for various axion models.