Pion polarizabilities: Theory vs Experiment

Abstract

The values of charged pion polarizabilities obtained in the framework of chiral perturbation theory at the level of two-loop accuracy are compared with the experimental result recently reported by COMPASS Collaboration. It is found that the calculated value for the dipole polarizabilities $(\alpha-\beta)_{\pi^\pm}= (5.7\pm 1.0)\times 10^{-4}\,{\rm fm}^3$ fits quite well the experimental result $(\alpha-\beta)_{\pi^\pm} = (4.0 \pm 1.2_{\rm stat} \pm 1.4_{\rm syst}) \times 10^{-4}\,{\rm fm}^3$.