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Dipole Polarizabilities of π±-Mesons

“…The COMPASS collaboration analyzed this process up to the total energy W = 490 MeV in the angular range 0.15 > cos θ cm γπ > −1. However, the contribution of the σ-meson to the cross section of the Compton scattering on the pion could be very substantial in this region of the energy and angles [23]. Therefore, we consider this contribution.…”

“…According the dispersion relation (DR) from Ref. [23] the contribution of the σ-meson can be determined as…”

“…The processes γγ → π 0 π 0 and γγ → π + π − were analyzed in Refs. [11,23,31] using DR with subtractions for the invariant amplitudes M ++ and M +− without an expansion over partial waves. The subtraction constants are uniquely determined in these works through the pion polarizabilities.…”

“…DSR for the difference and sum of electric and magnetic pion polarizabilities have been constructed in Refs. [11,23,31,33]. The main contribution to DSR for (α 1 − β 1 ) π ± is given by σ-meson.…”