A Search for the Rare Leptonic B- to tau- anti-neutrino Recoiling against B+ to Decays to anti-D*0 l+ Lepton-neutrino

Datta, Mousumi

Stanford Linear Accelerator Center

关键词: Decay;    43 Particle Accelerators;    Experiment-Hep,Hepex;    Stanford Linear Accelerator Center;    Leptons;   

DOI  :  10.2172/893772
RP-ID  :  SLAC-R-597
RP-ID  :  AC02-76SF00515
RP-ID  :  893772

美国|英语

来源: UNT Digital Library

【 摘 要 】

This thesis describes a search for the decay B{sup -} {yields} {tau}{sup -}{bar {nu}}{sub {tau}} in 231.8 x 10{sup 6} {Upsilon}(4S) decays recorded with the BABAR detector at the SLAC PEP-II B-Factory. A sample of events with one reconstructed exclusive semi-leptonic B decay (B{sup +} {yields} {bar D}*{sup 0} {ell}{sup +}{nu}{sub {ell}}) is selected, and in the recoil a search for B{sup -} {yields} {tau}{sup -} {bar {nu}}{sub {tau}} signal is performed in the following {tau} decay modes: {tau}{sup -} {yields} e{sup -}{bar {nu}}{sub e}{nu}{sub {tau}}, {tau}{sup -} {yields} {mu}{sup -}{bar {nu}}{sub {mu}}{nu}{sub {tau}}, {tau}{sup -} {yields} {pi}{sup -}{nu}{sub {tau}}, {tau}{sup -} {yields} {pi}{sup -}{pi}{sup 0}{nu}{sub {tau}}, and {tau}{sup -} {yields} {pi}{sup -}{pi}{sup +}{pi}{sup -}{nu}{sub {tau}}. They find no evidence of signal, and they set a preliminary upper limit on the branching fraction of {beta}(B{sup -} {yields} {tau}{sup -}{bar {nu}}{sub {tau}}) < 2.8 x 10{sup -4} at the 90% confidence level (CL). This result is then combined with a statistically independent BABAR search for B{sup -} {yields} {tau}{sup -}{bar {nu}}{sub {tau}} to give a combined preliminary limit of {Beta}(B{sup -} {yields} {tau}{sup -}{bar {nu}}{sub {tau}}) < 2.6 x 10{sup -4} at 90% CL.