학술논문
Search for lepton flavour violating muon decay mediated by a new light particle in the MEG experiment
Document Type
article
Author
A. M. Baldini; F. Berg; M. Biasotti; G. Boca; P. W. Cattaneo; G. Cavoto; F. Cei; M. Chiappini; G. Chiarello; C. Chiri; A. Corvaglia; A. de Bari; M. De Gerone; M. Francesconi; L. Galli; F. Gatti; F. Grancagnolo; M. Grassi; D. N. Grigoriev; M. Hildebrandt; Z. Hodge; K. Ieki; F. Ignatov; R. Iwai; T. Iwamoto; S. Kobayashi; P.-R. Kettle; W. Kyle; N. Khomutov; A. Kolesnikov; N. Kravchuk; N. Kuchinskiy; T. Libeiro; G. M. A. Lim; V. Malyshev; N. Matsuzawa; M. Meucci; S. Mihara; W. Molzon; Toshinori Mori; A. Mtchedilishvili; M. Nakao; H. Natori; D. Nicolò; H. Nishiguchi; M. Nishimura; S. Ogawa; R. Onda; W. Ootani; A. Oya; D. Palo; M. Panareo; A. Papa; V. Pettinacci; G. Pizzigoni; A. Popov; F. Renga; S. Ritt; A. Rozhdestvensky; M. Rossella; R. Sawada; P. Schwendimann; G. Signorelli; A. Stoykov; G. F. Tassielli; K. Toyoda; Y. Uchiyama; M. Usami; C. Voena; K. Yanai; Yu. V. Yudin
Source
European Physical Journal C: Particles and Fields, Vol 80, Iss 9, Pp 1-21 (2020)
Subject
Language
English
ISSN
1434-6044
1434-6052
1434-6052
Abstract
Abstract We present the first direct search for lepton flavour violating muon decay mediated by a new light particle X, $$\upmu ^+ \rightarrow \mathrm {e}^+\mathrm {X}, \mathrm {X} \rightarrow \upgamma \upgamma \ $$ μ + → e + X , X → γ γ . This search uses a dataset resulting from $$7.5\times 10^{14}$$ 7.5 × 10 14 stopped muons collected by the MEG experiment at the Paul Scherrer Institut in the period 2009–2013. No significant excess is found in the mass region 20–45 MeV/c $$^2$$ 2 for lifetimes below 40 ps, and we set the most stringent branching ratio upper limits in the mass region of 20–40 MeV/c $$^2$$ 2 , down to $${\mathcal {O}}(10^{-11})$$ O ( 10 - 11 ) at 90% confidence level.