Pion polarizabilities and charged pion-pair production to two loops Original Research Article

We evaluate the electric and magnetic polarizabilities of charged pions in the framework of chiral perturbation theory at next-to-leading order. This requires a two-loop evaluation of the Compton amplitude near threshold. In addition we discuss the amplitude and cross section of pion-pair production for charged pions to two loops. The three new coupling constants that enter the result at this order in the low-energy expansion are estimated via resonance saturation. The predictions are compared with available experimental information.