Measurement of the branching ratio and form factor of KL→μ+μ- γ

M. B. Spencer, K. Arisaka, D. Roberts, W. Slater, M. Weaver, R. A. Briere, E. Cheu, D. A. Harris, P. Krolak, K. S. McFarland, A. Roodman, B. Schwingenheuer, S. V. Somalwar, Y. W. Wah, B. Winstein, R. Winston, A. R. Barker, E. C. Swallow, G. J. Bock, R. ColemanM. Crisler, J. Enagonio, R. Ford, Y. B. Hsiung, D. A. Jensen, E. Ramberg, R. Tschirhart, E. M. Collins, G. D. Gollin, T. Nakaya, T. Yamanaka, P. Gu, P. Haas, W. P. Hogan, S. K. Kim, J. N. Matthews, S. S. Myung, S. Schnetzer, G. B. Thomson, Y. Zou

Research output: Contribution to journalArticle

19 Scopus citations


We report on a measurement of the decay KL→μ+μ-γ from Fermilab experiment E799. We observe 207 candidate signal events with an estimated background of 10.5±4.0 events and establish B(KL→μ+μ-γ)=[3.23±0.23(stat)±0.19(syst)] ×10-7. This provides the first measurement of the Kγγ* form factor in the muonic Dalitz decay mode of the KL.

Original languageEnglish (US)
Pages (from-to)3323-3326
Number of pages4
JournalPhysical review letters
Issue number17
StatePublished - Jan 1 1995
Externally publishedYes

ASJC Scopus subject areas

  • Physics and Astronomy(all)

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    Spencer, M. B., Arisaka, K., Roberts, D., Slater, W., Weaver, M., Briere, R. A., Cheu, E., Harris, D. A., Krolak, P., McFarland, K. S., Roodman, A., Schwingenheuer, B., Somalwar, S. V., Wah, Y. W., Winstein, B., Winston, R., Barker, A. R., Swallow, E. C., Bock, G. J., ... Zou, Y. (1995). Measurement of the branching ratio and form factor of KL→μ+μ- γ. Physical review letters, 74(17), 3323-3326.