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arXiv · hep-ex/9708011

Observation of the Decay K^+ --> pi^+ gamma gamma

E787 Collaboration·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. Convery·M. 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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Abstract

The first observation of the decay K^+ --> pi^+ gamma gamma is reported. A total of 31 events was observed with an estimated background of 5.1 +- 3.3 events in the pi+ momentum range from 100 MeV/c to 180 MeV/c. The corresponding partial branching ratio, B(K+ -> pi+ gamma gamma, 100 MeV/c < P_pi^+ < 180 MeV/c), is (6.0 +- 1.5 (stat) +- 0.7 (sys)) x 10^{-7}. No K^+ --> pi^+ gamma gamma decay was observed in the pi^+ momentum region greater than 215 MeV/c. The observed pi^+ momentum spectrum is compared with the predictions of chiral perturbation theory.

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E787 Collaboration, 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. Convery, M. 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. 1997-10-22. Observation of the Decay K^+ --> pi^+ gamma gamma. https://doi.org/10.1103/physrevlett.79.4079

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