Fully differential NLO predictions for the radiative decay of muons and taus

Abstract

We present a general purpose Monte Carlo program for the calculation of the radiative muon decay $\mu \to e\nu \bar{\nu }\gamma$ and the radiative decays $\tau \to e\nu \bar{\nu }\gamma$ and $\tau \to \mu \nu \bar{\nu }\gamma$ at next-to-leading order in the Fermi theory. The full dependence on the lepton masses and polarization of the initial-sate lepton are kept. We study the branching ratios for these processes and show that fully-differential next-to-leading order corrections are important for addressing a tension between BaBar's recent measurement of the branching ratio $\mathcal{B}(\tau \to e\nu \bar{\nu }\gamma )$ and the Standard Model prediction. In addition, we study various distributions of the process $\mu \to e\nu \bar{\nu }\gamma$ and obtain precise predictions for the irreducible background to $\mu \to e\gamma$ searches, tailored to the geometry of the MEG detector.

arXiv comment14 pages, 5 figures, published version

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Cited by in corpus (7)

• QED at NNLO with McMule
• Search for lepton flavour violating muon decay mediated by a new light particle in the MEG experiment
• Low-energy lepton physics in the MRSSM: $(g-2{)}_{\mu }$, $\mu \to e\gamma$ and $\mu \to e$ conversion
• A theory vade mecum for PSI experiments
• Fully differential NLO predictions for rare and radiative lepton decays
• Testing $WW\gamma$ vertex in radiative muon decay
• Effective-field theories for charged lepton flavour violation