A search for two body muon decay signals

R. Bayes; J. Bueno; Yu. I. Davydov; P. Depommier; W. Faszer; M. C. Fujiwara; C. A. Gagliardi; A. Gaponenko; D. R. Gill; A. Grossheim; P. Gumplinger; M. D. Hasinoff; R. S. Henderson; A. Hillairet; J. Hu; D. D. Koetke; R. P. MacDonald; G. M. Marshall; E. L. Mathie; R. E. Mischke; K. Olchanski; A. Olin; R. Openshaw; J. -M. Poutissou; R. Poutissou; V. Selivanov; G. Sheffer; B. Shin; T. D. S. Stanislaus; R. Tacik; R. E. Tribble

doi:10.1103/physrevd.91.052020

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arXiv · 1409.0638

A search for two body muon decay signals

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Abstract

Lepton family number violation is tested by searching for $\mu^+\to e^+X^0$ decays among the 5.8$\times 10^8$ positive muon decay events analyzed by the TWIST collaboration. Limits are set on the production of both massless and massive $X^0$ bosons. The large angular acceptance of this experiment allows limits to be placed on anisotropic $\mu^+\to e^+X^0$ decays, which can arise from interactions violating both lepton flavor and parity conservation. Branching ratio limits of order $10^{-5}$ are obtained for bosons with masses of 13 - 80 MeV/c$^2$ and with different decay asymmetries. For bosons with masses less than 13 MeV/c$^{2}$ the asymmetry dependence is much stronger and the 90% limit on the branching ratio varies up to $5.8 \times 10^{-5}$. This is the first study that explicitly evaluates the limits for anisotropic two body muon decays.

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R. Bayes, J. Bueno, Yu. I. Davydov, P. Depommier, W. Faszer, M. C. Fujiwara, C. A. Gagliardi, A. Gaponenko, D. R. Gill, A. Grossheim, P. Gumplinger, M. D. Hasinoff, R. S. Henderson, A. Hillairet, J. Hu, D. D. Koetke, R. P. MacDonald, G. M. Marshall, E. L. Mathie, R. E. Mischke, K. Olchanski, A. Olin, R. Openshaw, J. -M. Poutissou, R. Poutissou, V. Selivanov, G. Sheffer, B. Shin, T. D. S. Stanislaus, R. Tacik, R. E. Tribble. 2014-09-02. A search for two body muon decay signals. https://doi.org/10.1103/physrevd.91.052020

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