ISSN - 00319007, EISSN - 10797114, Physical Review Letters, 2004, vol. 92, p. 171802-1
Upper bound on the decay τ μγ from the Belle detector
A study using 86.3 fb-1 of data collected at the γ(4S) resonance with the Belle detector at the KEKB asymmetric e+e - collider was presented. An event composed of exactly two oppositely charged tracks and one photon candidate, that is consistent with a τ+τ- event in which one τ decays to μγ and the other τ decys to a non muon charged particle, neutrinos and any number of γs was searched for. The selection criteria were determined by examining Monte Carlo simulations for signal τpair decay and background events. It was also assumed that the two body decay τ→μγ had a uniform angular distribution in the τ's rest system.