LHCb

Abstract:

A search for the nonconservation of lepton flavor in the decay τ±→e±γ has been performed with 2.07×108 e+e-→τ+τ- events collected by the BABAR detector at the SLAC PEP II storage ring at a center-of-mass energy near 10.58 GeV. We find no evidence for a signal and set an upper limit on the branching ratio of B(τ±→ e±γ)<1.1×10-7 at 90% confidence level. © 2006 The American Physical Society.

Abstract:

The four LEP collaborations, ALEPH, DELPHI, L3 and OPAL, have searched for the neutral Higgs bosons which are predicted by the Minimal Supersymmetric standard model (MSSM). The data of the four collaborations are statistically combined and examined for their consistency with the background hypothesis and with a possible Higgs boson signal. The combined LEP data show no significant excess of events which would indicate the production of Higgs bosons. The search results are used to set upper bounds on the cross-sections of various Higgs-like event topologies. The results are interpreted within the MSSM in a number of "benchmark" models, including CP-conserving and CP-violating scenarios. These interpretations lead in all cases to large exclusions in the MSSM parameter space. Absolute limits are set on the parameter tan β and, in some scenarios, on the masses of neutral Higgs bosons.

Abstract:

We report on searches for B-→Ds- and B-→Ds*-. In the context of the standard model, these decays are expected to be highly suppressed since they proceed through annihilation of the b and ū quarks in the B- meson. Our results are based on 234×106 Υ(4S)→BB̄ decays collected with the BABAR detector at SLAC. We find no evidence for these decays, and we set Bayesian 90% confidence level upper limits on the branching fractions B(B-→Ds-)<1.9×10-6 and B(B-→Ds*-)<1. 2×10-5. These results are consistent with standard model expectations. © 2006 The American Physical Society.

Abstract:

We search for the charmed pentaquark candidate reported by the H1 collaboration, the Θc(3100)0, in e+e- interactions at a center-of-mass (c.m.) energy of 10.58 GeV, using 124fb-1 of data recorded with the BABAR detector at the PEP-II e+e- facility at SLAC. We find no evidence for such a state in the same pD*- decay mode reported by H1, and we set limits on its production cross section times branching fraction into pD*- as a function of c.m. momentum. The corresponding limit on its total rate per e+e-→qq̄ event, times branching fraction, is about 3 orders of magnitude lower than rates measured for the charmed Λc and Σc baryons in such events. © 2006 The American Physical Society.

Abstract:

We present a search for the rare B-meson decay B0→a1±ρ with a1±→π+π-π±. We use (110±1.2) ×106Υ(4S)→BB̄ decays collected with the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. We obtain an upper limit of 30×10-6(90%C.L.) for the branching fraction product B(B0→a1± ρ)B(a1±→π+π-π±), where we assume that the a1± decays exclusively to ρ0π±. © 2006 The American Physical Society.