학술논문
A search for $$\upmu ^+ \rightarrow \textrm{e}^+ \upgamma $$ μ + → e + γ with the first dataset of the MEG II experiment
Document Type
article
Author
K. Afanaciev; A. M. Baldini; S. Ban; V. Baranov; H. Benmansour; M. Biasotti; G. Boca; P. W. Cattaneo; G. Cavoto; F. Cei; M. Chiappini; G. Chiarello; A. Corvaglia; F. Cuna; G. Dal Maso; A. De Bari; M. De Gerone; L. Ferrari Barusso; M. Francesconi; L. Galli; G. Gallucci; F. Gatti; L. Gerritzen; F. Grancagnolo; E. G. Grandoni; M. Grassi; D. N. Grigoriev; M. Hildebrandt; K. Ieki; F. Ignatov; F. Ikeda; T. Iwamoto; S. Karpov; P.-R. Kettle; N. Khomutov; S. Kobayashi; A. Kolesnikov; N. Kravchuk; V. Krylov; N. Kuchinskiy; W. Kyle; T. Libeiro; V. Malyshev; A. Matsushita; M. Meucci; S. Mihara; W. Molzon; Toshinori Mori; M. Nakao; D. Nicolò; H. Nishiguchi; A. Ochi; S. Ogawa; R. Onda; W. Ootani; A. Oya; D. Palo; M. Panareo; A. Papa; V. Pettinacci; A. Popov; F. Renga; S. Ritt; M. Rossella; A. Rozhdestvensky; P. Schwendimann; K. Shimada; G. Signorelli; M. Takahashi; G. F. Tassielli; K. Toyoda; Y. Uchiyama; M. Usami; A. Venturini; B. Vitali; C. Voena; K. Yamamoto; K. Yanai; T. Yonemoto; K. Yoshida; Yu. V. Yudin; MEG II Collaboration
Source
European Physical Journal C: Particles and Fields, Vol 84, Iss 3, Pp 1-10 (2024)
Subject
Language
English
ISSN
1434-6052
Abstract
Abstract The MEG II experiment, based at the Paul Scherrer Institut in Switzerland, reports the result of a search for the decay $$\upmu ^+ \rightarrow {\textrm{e}}^+ \upgamma $$ μ + → e + γ from data taken in the first physics run in 2021. No excess of events over the expected background is observed, yielding an upper limit on the branching ratio of $${\mathcal {B}} (\upmu ^+ \rightarrow {\textrm{e}}^+ \upgamma ) < 7.5 \times 10^{-13}$$ B ( μ + → e + γ ) < 7.5 × 10 - 13 (90% CL). The combination of this result and the limit obtained by MEG gives $${\mathcal {B}} (\upmu ^+ \rightarrow {\textrm{e}}^+ \upgamma ) < 3.1 \times 10^{-13}$$ B ( μ + → e + γ ) < 3.1 × 10 - 13 (90% CL), which is the most stringent limit to date. A ten-fold larger sample of data is being collected during the years 2022–2023, and data-taking will continue in the coming years.