Measurement of the Branching Ratio and Form Factor of KL→μ+μ-γ

KTeV Collaboration

Research output: Contribution to journalArticlepeer-review


We report on the analysis of the rare decay KL→μ+μ-γ the 1997 data from the KTeV experiment at Fermilab. A total of 9327 candidate events are observed with 2.4% background, representing a factor of 40 increase in statistics over the current world sample. We find that B(KL→μ+μ-γ)=(3.62±0.04stat±0.08syst)×10-7. The form factor parameter αK* is measured to be αK*=-0.160-0.028+0.026. In addition, we make the first measurement of the parameter α from the D’Ambrosio-Isidori-Portolés form factor, finding α=-1.54±0.10. In that model, this α measurement limits the Cabibbo-Kobayashi-Maskawa parameter ρ>-0.2.

Original languageEnglish (US)
Pages (from-to)71801-1-71801-4
JournalPhysical review letters
Issue number7
StatePublished - Aug 13 2001

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)


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