# Searches for the decays $B^0 \to l^+ \tau^-$ and $B^+ \to l^+ \nu (l=e,\mu)$ using hadronic tag reconstruction

Abstract : We present searches for the leptonic decays B+ -> l+ nu and the lepton flavor violating decays B0 -> l+ tau-, where l=e,mu, with data collected by the BaBar experiment at SLAC. This search demonstrates a novel technique in which we fully reconstruct the accompanying Bbar in Upsilon(4S)->BBbar events, and look for a monoenergetic lepton from the signal B decay. The signal yield is extracted from a fit to the signal lepton candidate momentum distribution in the signal B rest frame. Using a data sample of approximately 378 million BBbar pairs (342fb-1), we find no evidence of signal in any of the decay modes. Branching fraction upper limits of B(B+ -> e+ nu)<5.2x10^-6, B(B+ -> mu+ nu)<5.6x10^-6, B(B0 -> e+ tau-)<2.8x10^-5 and B(B0 -> mu+ tau-)<2.2x10^-5, are obtained at 90% confidence level.
Document type :
Journal articles

http://hal.in2p3.fr/in2p3-00222773
Contributor : Claudine Bombar <>
Submitted on : Tuesday, January 29, 2008 - 2:15:57 PM
Last modification on : Thursday, April 8, 2021 - 4:26:02 PM

### Citation

B. Aubert, M. Bona, Y. Karyotakis, J.P. Lees, V. Poireau, et al.. Searches for the decays $B^0 \to l^+ \tau^-$ and $B^+ \to l^+ \nu (l=e,\mu)$ using hadronic tag reconstruction. Physical Review D, American Physical Society, 2008, 77, 091104 (9p.). ⟨10.1103/PhysRevD.77.091104⟩. ⟨in2p3-00222773⟩

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