2026-04-13T06:38:35Zhttps://recercat.cat/oai/request

oai:recercat.cat:2445/1314442025-12-05T16:49:55Zcom_2072_1057col_2072_478823col_2072_478917

RECERCAT author Garra Ticó, Jordi author Graugés Pous, Eugeni author BABAR Collaboration 2019-04-04T13:51:04Z2019-04-04T13:51:04Z2007-09-182019-04-04T13:51:04Z We present a search for the decay B + → τ + ν using 383 × 10 6 B ¯¯¯ B pairs collected at the Υ ( 4 S ) resonance with the BABAR detector at the SLAC PEP-II B -Factory. A sample of events with one reconstructed semileptonic B decay ( B − → D 0 ℓ − ¯ ν ℓ X ) is selected, and in the recoil a search for B + → τ + ν is performed. The τ is identified in the following channels: τ + → e + ν ¯ ν , τ + → μ + ν ¯ ν , τ + → π + ¯ ν , and τ + → π + π 0 ¯ ν . We measure a branching fraction of B ( B + → τ + ν ) = ( 0.9 ± 0.6 ( stat . ) ± 0.1 ( syst . ) ) × 10 − 4 . In the absence of a significant signal, we calculate an upper limit at the 90% confidence level of B ( B + → τ + ν ) < 1.7 × 10 − 4 . We calculate the product of the B meson decay constant f B and | V ub | to be f B ⋅ | V ub | = ( 7.2 + 2.0 − 2.8 ( stat . ) ± 0.2 ( syst . ) ) × 10 − 4 GeV . (c) American Physical Society, 2007 info:eu-repo/semantics/openAccess Física de partícules Experiments Particle physics Experiments Search for B+ → τ+ν info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion