D. Sahoo, K. Trabelsi, et al. (Belle Collaboration)

Phys. Rev. D 102, 111101 (2020)

We search for lepton-number- and baryon-number-violating decays τ−→p¯¯¯e+e−, pe−e−, p¯¯¯e+μ−, p¯¯¯e−μ+, p¯¯¯μ+μ−, and pμ−μ− using 921 fb−1 of data, equivalent to (841±12)×106 τ+τ− events, recorded with the Belle detector at the KEKB asymmetric-energy e+e− collider. In the absence of a signal, 90% confidence-level upper limits are set on the branching fractions of these decays in the range (1.8-4.0)×10−8. We set the world's first limits on the first four channels and improve the existing limits by an order of magnitude for the last two channels.

2021-01-19 14:45