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ISSN - 15507998, Physical Review D - Particles, Fields, Gravitation and Cosmology, 2008, vol. 77, p. -

Searches for the decays B0→l±τ... and B+→l+ν (l=e, μ) using hadronic tag reconstruction

Aubert B., Bona M., Karyotakis Y., Lees J. P., Poireau V., Prudent X., Tisserand V., Zghiche A., Tico J. Garra, Grauges E., Lopez L., Palano A., Pappagallo M., Eigen G., Stugu B., Sun L., Abrams G. S., Battaglia M., Brown D. N., Button-Shafer J., Cahn R. N., Jacobsen R. G., Kadyk J. A., Kerth L. T., Kolomensky Yu G., Kukartsev G., Pegna D. Lopes, Lynch G., Osipenkov I. L., Ronan M. T., Tackmann K., Tanabe T., Wenzel W. A., Del Amo Sanchez P., Hawkes C. M., Soni N., Watson A. T., Koch H., Schroeder T., Walker D., Asgeirsson D. J., Cuhadar-Donszelmann T., Fulsom B. G., Hearty C., Mattison T. S., McKenna J. A., Barrett M., Khan A., Saleem M., Teodorescu L., Blinov V. E., Bukin A. D., Buzykaev A. R., Druzhinin V. P., Golubev V. B., Onuchin A. P., Serednyakov S. I., Skovpen Yu I., Solodov E. P., Todyshev K. Yu, Bondioli M., Curry S., Eschrich I., Kirkby D., Lankford A. J., Lund P., Mandelkern M., Martin E. C., Stoker D. P., Abachi S., Buchanan C., Gary J. W., Liu F., Long O., Shen B. C., Vitug G. M., Zhang L., Paar H. P., Rahatlou S., Sharma V., Campagnari C., Hong T. M., Kovalskyi D., Richman J. D., Beck T. W., Eisner A. M., Flacco C. J., Heusch C. A., Kroseberg J., Lockman W. S., Schalk T., Schumm B. A., Seiden A., Wilson M. G., Winstrom L. O., Chen E., Cheng C. H., Doll D. A., Echenard B., Fang F.

We present searches for the leptonic decays B+→ℓ+ν and the lepton flavor violating decays B0→ℓ±τ, where ℓ=e, μ, with data collected by the BABAR experiment at SLAC. This search demonstrates a novel technique in which we fully reconstruct the accompanying B̄ in Υ(4S)→BB̄ 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 378×106 BB̄ pairs (342fb-1), we find no evidence of signal in any of the decay modes. Branching fraction upper limits of B(B+→e+ν)<5.2×10-6, B(B+→μ+ν)<5.6×10-6, B(B0→e+τ-)<2.8×10-5 and B(B0→μ+τ-)<2. 2×10-5, are obtained at 90% confidence level. © 2008 The American Physical Society.