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3 results on '"W. Ootani"'

1. A search for $$\upmu ^+ \rightarrow \textrm{e}^+ \upgamma $$ μ + → e + γ with the first dataset of the MEG II experiment

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, and MEG II Collaboration

Subjects
Astrophysics, QB460-466, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
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.

Published
2024
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2. Search for lepton flavour violating muon decay mediated by a new light particle in the MEG experiment

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, and Yu. V. Yudin

Subjects
Astrophysics, QB460-466, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
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.

Published
2020
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3. The design of the MEG II experiment

Author

A. M. Baldini, E. Baracchini, C. Bemporad, F. Berg, M. Biasotti, G. Boca, P. W. Cattaneo, G. Cavoto, F. Cei, M. Chiappini, G. Chiarello, C. Chiri, G. Cocciolo, A. Corvaglia, A. de Bari, M. De Gerone, A. D’Onofrio, M. Francesconi, Y. Fujii, L. Galli, F. Gatti, F. Grancagnolo, M. Grassi, D. N. Grigoriev, M. Hildebrandt, Z. Hodge, K. Ieki, F. Ignatov, R. Iwai, T. Iwamoto, D. Kaneko, K. Kasami, P.-R. Kettle, B. I. Khazin, N. Khomutov, A. Korenchenko, N. Kravchuk, T. Libeiro, M. Maki, N. Matsuzawa, S. Mihara, M. Milgie, W. Molzon, Toshinori Mori, F. Morsani, A. Mtchedilishvili, M. Nakao, S. Nakaura, D. Nicolò, H. Nishiguchi, M. Nishimura, S. Ogawa, W. Ootani, M. Panareo, A. Papa, A. Pepino, G. Piredda, A. Popov, F. Raffaelli, F. Renga, E. Ripiccini, S. Ritt, M. Rossella, G. Rutar, R. Sawada, G. Signorelli, M. Simonetta, G. F. Tassielli, Y. Uchiyama, M. Usami, M. Venturini, C. Voena, K. Yoshida, Yu. V. Yudin, and Y. Zhang

Subjects
Astrophysics, QB460-466, Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract

Abstract The MEG experiment, designed to search for the $${\mu ^+ \rightarrow \hbox {e}^+ \gamma }$$ μ+→e+γ decay, completed data-taking in 2013 reaching a sensitivity level of $${5.3\times 10^{-13}}$$ 5.3×10-13 for the branching ratio. In order to increase the sensitivity reach of the experiment by an order of magnitude to the level of $$6\times 10^{-14}$$ 6×10-14 , a total upgrade, involving substantial changes to the experiment, has been undertaken, known as MEG II. We present both the motivation for the upgrade and a detailed overview of the design of the experiment and of the expected detector performance.

Published
2018
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