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arXiv · hep-ph/9902284

Rare Pionium Decays and Pion Polarizability

H. -W. Hammer·J. N. Ng
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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.

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H. -W. Hammer, J. N. Ng. 1999-06-29. Rare Pionium Decays and Pion Polarizability. https://doi.org/10.1007/s100500050324

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