A Search for the rare decay B0 --> tau+tau- at BABAR

Abstract

We present the results of a search for the decay B0 --> tau+tau- in a data sample of (232 +- 3) x 10^6 Upsilon(4S) --> BBbar decays using the BABAR detector. Certain extensions of the Standard Model predict measurable levels of this otherwise rare decay. We reconstruct fully one neutral B meson and seek evidence for the signal decay in the rest of the event. We find no evidence for signal events and obtain B(B0 --> tau+tau-) < 4.1 x 10^-3 at the 90% confidence level.