Observation of the Decay K+ → π+γγ

P. Kitching, T. Nakano, M. Rozon, R. Soluk, S. Adler, M. S. Atiya, I. H. Chiang, J. S. Frank, J. S. Haggerty, T. F. Kycia, K. K. Li, L. S. Littenberg, A. Sambamurti, A. Stevens, R. C. Strand, C. Witzig, W. C. Louis, D. S. Akerib, M. Ardebili, M. ConveryM. M. Ito, D. R. Marlow, R. A. McPherson, P. D. Meyers, M. A. Selen, F. C. Shoemaker, A. J.S. Smith, E. W. Blackmore, D. A. Bryman, L. Felawka, A. Konaka, Y. Kuno, J. A. Macdonald, T. Numao, P. Padley, J. M. Poutissou, R. Poutissou, J. Roy, A. S. Turcot

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74 Scopus citations


The first observation of the decay K+ → π+γγ is reported. A total of 31 events was observed with an estimated background of 5.1 ± 3.3. events in the π+ momentum range from 100 to 180 MeV/c. The corresponding partial branching ratio, B(K+ → π+γγ, 100 MeV/c < Pπ+ < 180 MeV/c), is [6.0 ± 1.5(stat) ± 0.7(stat) × 10−7. No K+ → π+γγ decay was observed in the π+ momentum region greater than 215 MeV/c. The observed π+ momentum spectrum is compared with the predictions of chiral perturbation theory.

Original languageEnglish (US)
Pages (from-to)4079-4082
Number of pages4
JournalPhysical review letters
Issue number21
StatePublished - Nov 24 1997

All Science Journal Classification (ASJC) codes

  • General Physics and Astronomy


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