Measurement of structure dependent radiative K+ → e+νγ decays using stopped positive kaons
oleh: H. Ito, A. Kobayashi, S. Bianchin, T. Cao, C. Djalali, D.H. Dongwi, T. Gautam, D. Gill, M.D. Hasinoff, K. Horie, Y. Igarashi, J. Imazato, N. Kalantarians, H. Kawai, S. Kimura, S. Kodama, M. Kohl, H. Lu, O. Mineev, P. Monaghan, S. Shimizu, S. Strauch, M. Tabata, R. Tanuma, A. Toyoda, H. Yamazaki, N. Yershov
| Format: | Article |
|---|---|
| Diterbitkan: | Elsevier 2022-03-01 |
Deskripsi
The structure dependent radiative K+→e+νγ (Ke2γSD+) decay was investigated with stopped positive kaons. The e+ momentum spectra containing 574±30 Ke2γSD+ events with a K+→μ+ν (Kμ2) background of 28±19 events were measured with and without a photon in coincidence and analyzed with Monte Carlo simulations for acceptance and detector response to extract the ratio of the branching ratio of the Ke2γSD+ decay and the K+→e+ν decay including the internal bremsstrahlung process (Ke2(γ)). A value of Br(Ke2γSD+)/Br(Ke2(γ))=1.12±0.07stat±0.04syst was obtained. This indicates a partial branching ratio, Br(Ke2γSD+,pe>200MeV/c,Eγ>10MeV)/Br(Kμ2)=(1.85±0.11stat±0.07syst)×10−5, which is 25% (∼2.5σ) higher than the previous experimental result.