We studied the radiative muon decay μ+ → e+ νν ̄ γ by using for the first time an almost fully polarized muon source. We identified a large sample (∼13,000) of these decays in a total sample of 1.8 × 1014 positive muon decays collected in the MEG experiment in the years 2009– 2010 and measured the branching ratio B(μ → eνν ̄γ) = (6.03 ± 0.14(stat.) ± 0.53(sys.)) × 10−8 for Ee > 45 MeV and Eγ > 40 MeV, consistent with the Standard Model prediction. The precise measurement of this decay mode pro- vides a basic tool for the timing calibration, a normalization channel, and a strong quality check of the complete MEG experiment in the search for μ+ → e+γ process.
Measurement of the radiative decay of polarized muons in the MEG experiment / The MEG Collaboration, Null; Baldini, A. M.; Bao, Y.; Baracchini, E.; Bemporad, C.; Berg, F.; Biasotti, M.; Boca, G.; Cattaneo, P. W.; Cavoto, Gianluca; Cei, F.; Chiarello, G.; Chiri, C.; de Bari, A.; De Gerone, M.; D’Onofrio, A.; Dussoni, S.; Fujii, Y.; Galli, L.; Gatti, F.; Grancagnolo, F.; Grassi, M.; Graziosi, A.; Grigoriev, D. N.; Haruyama, T.; Hildebrandt, M.; Hodge, Z.; Ieki, K.; Ignatov, F.; Iwamoto, T.; Kaneko, D.; Kang, Tae Im; Kettle, P. R.; Khazin, B. I.; Khomutov, N.; Korenchenko, A.; Kravchuk, N.; Lim, G. M. A.; Mihara, S.; Molzon, W.; Mori, Toshinori; Mtchedlishvili, A.; Nakaura, S.; Nicolò, D.; Nishiguchi, H.; Nishimura, M.; Ogawa, S.; Ootani, W.; Panareo, M.; Papa, A.; Pepino, A.; Piredda, G.; Pizzigoni, G.; Popov, A.; Renga, F.; Ripiccini, Emanuele; Ritt, S.; Rossella, M.; Rutar, G.; Sawada, R.; Sergiampietri, F.; Signorelli, G.; Tassielli, G. F.; Tenchini, F.; Uchiyama, Y; Venturini, M.; Voena, C.; Yamamoto, A.; Yoshida, K.; You, Z.; Yudin, Y. u. V.. - In: THE EUROPEAN PHYSICAL JOURNAL. C, PARTICLES AND FIELDS. - ISSN 1434-6044. - 76:3(2016), pp. 1-8. [10.1140/epjc/s10052-016-3947-6]
Measurement of the radiative decay of polarized muons in the MEG experiment
CAVOTO, GianlucaMembro del Collaboration Group
;RIPICCINI, EMANUELEMembro del Collaboration Group
;Voena, C.;
2016
Abstract
We studied the radiative muon decay μ+ → e+ νν ̄ γ by using for the first time an almost fully polarized muon source. We identified a large sample (∼13,000) of these decays in a total sample of 1.8 × 1014 positive muon decays collected in the MEG experiment in the years 2009– 2010 and measured the branching ratio B(μ → eνν ̄γ) = (6.03 ± 0.14(stat.) ± 0.53(sys.)) × 10−8 for Ee > 45 MeV and Eγ > 40 MeV, consistent with the Standard Model prediction. The precise measurement of this decay mode pro- vides a basic tool for the timing calibration, a normalization channel, and a strong quality check of the complete MEG experiment in the search for μ+ → e+γ process.| File | Dimensione | Formato | |
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