Searching for New Physics in Rare $B\to \tau$ Decays

Dafne Guetta, Enrico Nardi

The rare decays {$B^{-}\to \tau \bar{\nu }$}, \mbox{$B\to {\tau }^{+}{\tau }^{-}$}, {$b\to X\nu \bar{\nu }$} and \mbox{$b\to X{\tau }^{+}{\tau }^{-}$} all contain third generation leptons in the final state, and hence are s…