Radiative Hyperon DecaysΣ±→n+π±+γ

The observation of the ${\Sigma }^{\pm }\to n+{\pi }^{\pm }+\gamma$ radiative-decay spectra has been proposed as a method of determining the $s$- or $p$-wave nature of the $\Sigma$ pionic decay. The previous theoretical treatment is based on a phenomenological interaction that neglects all form-factor effects. Calculations have been made to investigate the sensitivity of the theoretical predictions to structure effects by using two models: (a) a self-consistent pole model that includes the ${\Sigma }^{+}\to p+\gamma$ vertex in a natural way; (b) a loop model that serves as a demonstration of the radiative influence of a virtual light particle. The results show that the simple phenomenological calculation is not changed significantly. Hence, the reliability of the radiative-decay method to determine the $s$- or $p$-wave nature of $\Sigma$ pionic decay is improved.