Rare Decays in LHCb

European Organisation for Nuclear Research (CERN), Geneva, Switzerland

^a e-mail: diego.martinez.santos@cern.ch

Abstract

The rare B decays B_(s)⁰ → μ⁺μ⁻, B⁰ → K^*0μ⁺μ⁻ and B_s⁰ → φγ are studied using up to ~ 0.41 fb⁻¹ of pp collisions at √s = 7 TeV collected by the LHCb experiment in 2010 and 2011. A search for the decays B_(s)⁰ → μ⁺μ⁻ is performed with 0.41 fb⁻¹. The absence of significant signal leads to $B$(B_s⁰ → μ⁺μ⁻) < 1.4×10⁻⁸ and $B$(B⁰ → μ⁺μ⁻) < 3.2×10⁻⁹ at 95% confidence level. The forward-backward asymmetry, fraction of longitudinal polarization and differential branching fraction of B⁰ → K^*0μ⁺μ⁻, as a function of dimuon invariant mass, are measured in 0.31 fb⁻¹. The ratio of branching ratios of the radiative B decays B⁰ → K^*0γ and B_s⁰ → φγ has been measured using 0.34 fb⁻¹. The obtained value for the ratio is 1.52 ± 0.14(stat) ± 0.10(syst) ± 0.12(f_s/f_d). Using the HFAG value for $B$(B⁰ → K^*0γ), $B$(B_s⁰ → φγ) has been found to be (2.8 ± 0.5) × 10⁻⁵.