2002/07/24 by B. Aubert, Aubert, B.
Mathematics · Physics and Astronomy · #Astrophysics #Astrophysics and Cosmic Phenomena #Branching fraction #Detector #Event (particle physics) #FOS: Physical sciences #Geometry #High Energy Physics - Experiment (hep-ex) #Mathematics #Neutrino #Neutrino Physics Research #Nuclear physics #Optics #Particle identification #Particle physics #Particle physics theoretical and experimental studies #Physics #Signature (topology) #hep-ex
paper · pdf · doi:10.48550/arxiv.hep-ex/0207069
15 pages, 5 figures, International Conference on High Energy Physics 2002
arxiv created 2002/07/24 · openalex publication_date 2002/07/24 · arxiv updated 2009/11/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We present a preliminary search for the flavor-changing neutral current decay B+ -> K+ nunubar using 56 million Y(4S) decays recorded with the BABAR detector at the SLAC B factory. Identification of the B+ -> K+ nunubar final state, with two neutrinos, requires the reconstruction of the companion B in the event. The companion B is reconstructed in the decay mode B- -> D0 l- nubar X, which provides both high efficiency and good purity. The particles not used in the reconstruction of the companion B are compared with the signature expected for B+ -> K+ nunubar decays. Two candidates are found in the data with an expected background of 2.2 events. Under the assumption that all candidates are signal events, an upper limit on the branching fraction for B+ -> K+ nunubar of 9.4 x 10-5 at 90% confidence level is determined.