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, N., Baldini, A.M., Bao, Y., Baracchini, E., Bemporad, C., Berg, F., Biasotti, M., Boca, G., Cattaneo, P.W., Cavoto, G., Cei, F., Chiarello, G., Chiri, C., de Bari, A., De Gerone, M., D’Onofrio, A., Dussoni, S., Fujii, Y., Galli, L., Gatti, F., et al.. - 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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