PNNL

Abstract

We search for lepton-number- and baryon-number-violating decays t- ? p¯ eþe-, pe-e-, p¯ eþµ-, p¯ e-µþ, p¯ µþµ-, and pµ-µ- using 921 fb-1 of data, equivalent to 841 12 × 106 tþt- events, recorded with the Belle detector at the KEKB asymmetric-energy eþe- 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 er of magnitude for the last two channels.