Reviews of topical problems

Electromagnetic properties of pions at low energies

The theoretical structure of the pion-photon interaction amplitudes at low energies and the possibility of studying them experimentally are reviewed. It is pointed out that it is possible to measure the $\pi\pi$ scattering lengths in photon-pion transitions. For processes involving an odd number of pions, a discussion is given of the fundamental role of the $\pi^0\to2\gamma$ decay amplitude, which determines the form of all more complex amplitudes. This fact is connected with the anomalies in the axial-vector current that appears in the weak interaction. In processes involving an even number of pions, the radius and polarizability of the $\pi^-$ meson appear as basic parameters. The polarizability is related to the weak decay amplitude.

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Fulltext is also available at DOI: 10.1070/PU1974v017n01ABEH004315
PACS: 13.40.−f, 13.75.Gx, 13.20.Cz, 14.40.Aq, 13.88.+e, 14.70.Bh (all)
DOI: 10.1070/PU1974v017n01ABEH004315
Citation: Terent’ev M V "Electromagnetic properties of pions at low energies" Sov. Phys. Usp. 17 20–43 (1974)
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Оригинал: Терентьев М В «Электромагнитные свойства π-meзонов» УФН 112 37–82 (1974); DOI: 10.3367/UFNr.0112.197401b.0037

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