Pion polarizabilities: Theory vs Experiment

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 $(\alpha -\beta {)}_{{\pi }^{\pm }}=(5.7\pm 1.0)\times {10}^{-4}{\mathrm{f}\mathrm{m}}^3$ fits quite well the experimental result $(\alpha-\beta){\pi^\pm} = (4.0 \pm 1.2{\rm stat} \pm 1.4_{\rm syst}) \times 10^{-4},{\rm fm}^3$.