Search for new physics in rare decays at B-factories

BABAR and Belle detector collaborations operating at the B-Factories in KEK and SLAC have accumulated over 200 M BB-bar and τ+ τ- events. Using these data samples several measurements and searches for new physics contributions that involve flavor changing neutral currents and lepton flavor violation are made. In particular, results on processes involving electro-weak penguin transitions (b → sγ, b → dγ, b → sl+l-, b → sνν), purely leptonic B decays (B → l+l-, B → lν, B → νν) and lepton flavor changing τ decays (τ → μγ, τ → lll) are presented. No evidence for new physics is seen in either branching ratios or asymmetries measured for these processes. These results are all limited in precision by statistics, and are likely to improve significantly with increasing magnitude of datasets collected by BABAR and Belle experiments. (author)