Rare Pionium Decays and Pion Polarizability

Abstract

We calculate the decay of pionium atoms into two photons. The pion polarizability gives rise to a 10% correction to the corresponding decay width for pointlike pions. This opens the possibility to obtain the difference between the electric and magnetic polarizability of the charged pion from a future measurement of the branching fraction of pionium into two photons. For such an experiment the ππ-scattering lengths would have to be known to better than 5% precision. We also comment on the contribution of the axial anomaly to the decay of pionium into γπ^0.

7 pages, Latex, no figures, discussion and references added, version to appear in EPJ A

Cited by in corpus (9)

• ππscattering
• First measurement of the ${\pi }^{+}{\pi }^{-}$ atom lifetime
• Decays of the pi+ pi- atom
• Decay widths and energy shifts of pi pi and pi K atoms
• Partial wave analysis of pbar-p to Lambdabar-Lambda
• Spectra and decays of pi pi and pi K atoms
• Direct calculation of the probability of pionium ionization in the target
• Exclusive photon-fusion production of even-spin resonances and exotic QED atoms in high-energy hadron collisions
• Spectrum and decays of hadronic atoms