The electric απ and magnetic βπ charged pion polarizabilities characterize the induced dipole moments of the pion during γπ scattering. These fundamental characterisitcs of the pion provide stringent tests of various theoretical models, for example chiral perturbation theory (ChPT). CERN COMPASS investigated pion Compton scattering γπ → γπ, via radiative pion Primakoff scattering (Bremsstrahlung of 190 GeV/c negative pions) in the nuclear Coulomb field of the Ni nucleus: π + Ni → π + γ + Ni. The resulting data are equivalent to γπ Compton scattering for laboratory γ's having momenta of order 1 GeV/c incident on a target pion at rest. The data yield preliminary polarizability values απ = - βπ = (1.9±0.7stat±0.8 syst)×10-4fm3, in agreement with ChPT.
|Journal||Proceedings of Science|
|State||Published - 2013|
|Event||2013 European Physical Society Conference on High Energy Physics, EPS-HEP 2013 - Stockholm, Sweden|
Duration: 18 Jul 2013 → 24 Jul 2013