Pion photoproduction at threshold onLi6and low-energy theorems

Abstract

The Low, Kroll-Ruderman, and Fubini-Furlan-Rossetti theorems are derived in the case of pion photoproduction on ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$. Particular care has been taken to be consistent with electromagnetic current conservation and Low's theorem in the extrapolation from soft to real pions. This is new compared to previous treatments of soft pion theorems in nuclear processes where one photon is present. Difficulties due to the spin-1 nature of ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$ have been put forward.