# Measurement of the branching fractions of the radiative leptonic $τ$ decays $τ \to eγν¯ν$ and $τ \to µγν¯ν$ at $B\small AB\small AR$

J.P. Lees, G. Raven

## Abstract

We perform a measurement of the τ→lγνν¯ (l=e,μ) branching fractions for a minimum photon energy of 10 MeV in the τ rest frame, using 431fb-1 of e+e- collisions collected at the center-of-mass energy of the (4S) resonance with the BABAR detector at the PEP-II storage rings. We find B(τ→μγνν¯)=(3.69±0.03±0.10)×10-3 and B(τ→eγνν¯)=(1.847±0.015±0.052)×10-2, where the first quoted error is statistical and the second is systematic. These results are substantially more precise than previous measurements.
Original language English 051103 Physical Review D 91 https://doi.org/10.1103/PhysRevD.91.051103 Published - 2015

Lees:2015gea

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