Measurement of Structure Dependent Radiative K⁺ -> e,sup>(+) vy gamma Decays Using Stopped Positive Kaons

Author(s)

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
Steffen Strauch, University of South CarolinaFollow
Et. Al.

Document Type

Article

Abstract

The structure dependent radiative K + → e+νγ (K^SD+_e2γ) decay was investigated with stopped positive kaons. The e⁺ momentum spectra containing 574±30 K^SD+_e2γ events with a K + → μ+ν (K_μ2) 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 K^SD+_e2γ decay and the K + → e+ν decay including the internal bremsstrahlung process (K_{e2(γ )}). A value of Br(K^SD+_e2γ )/Br(Ke2(γ )) = 1.12 ± 0.07stat ± 0.04_syst was obtained. This indicates a partial branching ratio, Br(K^SD+_e2γ , p_e > 200 MeV/c, Eγ > 10 MeV)/Br(K_μ2) = (1.85 ± 0.11_stat ± 0.07_syst) × 10−5, which is 25% (∼2.5σ) higher than the previous experimental result.

Digital Object Identifier (DOI)

https://doi.org/10.1016/j.physletb.2022.136913

Publication Info

Published in Physics Letters B, Volume 826, 2022.

© 2022 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

APA Citation

Ito, H., Kobayashi, A., S. Bianchin, Cao, T., C. Djalali, D.H. Dongwi, Gautam, T., Gill, D., M.D. Hasinoff, Horie, K., Igarashi, Y., J. Imazato, N. Kalantarians, Kawai, H., Kimura, S., Kodama, S., Kohl, M., Lu, H., O. Mineev, & Monaghan, P. (2022). Measurement of structure dependent radiative K+ → e+νγ decays using stopped positive kaons. Physics Letters. B, 826. https://doi.org/10.1016/j.physletb.2022.136913