Abstract: We present a search for the decay of the charged B meson into a charged lepton and a neutrino 458.9 million Upsilon(4S) decays recorded with the Babar

"The flavour changing neutral current (FCNC) process , B+ → K+ [tau]+[tau]−, is highly sup-pressed in the Standard Model (SM). This decay is forbidden at tr

This thesis describes a search for the rare decay B + {yields} mu+numugamma, performed at the Stanford Linear Accelerator Center. The BABAR detector is used to