Plans for a measurement of pion polarizabilities at COMPASS

The pion electromagnetic structure can be probed in π−+(A,Z)→π−+(A,Z)+γ Compton scattering in inverse kinematics (Primakoff reaction) and described by the electric (απ) and the magnetic (βπ) polarizabilities that depend on the rigidity of pion's internal structure as a composite particle. Values for pion polarizabilities can be extracted from the comparison of the differential cross section for scattering of point-like pions with the measured cross section. The opportunity to measure pion polarizability via the Primakoff reaction at the COMPASS experiment was studied with a π− beam of 190 GeV. The obtained results are used for preparation of the new measurement.