LHCb

Abstract:

The decay B0→ψ(2S)K+π- is analyzed using 3 fb-1 of pp collision data collected with the LHCb detector. A model-independent description of the ψ(2S)π mass spectrum is obtained, using as input the Kπ mass spectrum and angular distribution derived directly from data, without requiring a theoretical description of resonance shapes or their interference. The hypothesis that the ψ(2S)π mass spectrum can be described in terms of Kπ reflections alone is rejected with more than 8σ significance. This provides confirmation, in a model-independent way, of the need for an additional resonant component in the mass region of the Z(4430)- exotic state.

Abstract:

We report a study of the suppressed B-→DK-π+π- and favored B-→Dπ-π+π- decays, where the neutral D meson is detected through its decays to the K π± and CP -even K+K- and π+π- final states. The measurement is carried out using a proton-proton collision data sample collected by the LHCb experiment, corresponding to an integrated luminosity of 3.0 fb-1. We observe the first significant signals in the CP -even final states of the D meson for both the suppressed B-→DK-π+π- and favored B-→Dπ-π+π- modes, as well as in the doubly Cabibbo suppressed D→K+π- final state of the B-→Dπ-π+π- decay. Evidence for the suppressed decay B-→DK-π+π-, with D→K+π-, is also presented. From the observed yields in the B-→DK-π+π-, B-→Dπ-π+π- and their charge conjugate decay modes, the most probable value of the weak phase γ corresponds to γ=(74-19+20)°. This is one of the most precise single-measurement determinations of γ to date.

Abstract:

Using a pp collision data sample corresponding to an integrated luminosity of 3.0  fb^{-1}, collected by the LHCb detector, we present the first search for the strangeness-changing weak decay Ξ_{b}^{-}→Λ_{b}^{0}π^{-}. No b hadron decay of this type has been seen before. A signal for this decay, corresponding to a significance of 3.2 standard deviations, is reported. The relative rate is measured to be f_{Ξ_{b}^{-}}/f_{Λ_{b}^{0}}B(Ξ_{b}^{-}→Λ_{b}^{0}π^{-})=(5.7±1.8_{-0.9}^{+0.8})×10^{-4},where f_{Ξ_{b}^{-}} and f_{Λ_{b}^{0}} are the b→Ξ_{b}^{-} and b→Λ_{b}^{0} fragmentation fractions, and B(Ξ_{b}^{-}→Λ_{b}^{0}π^{-}) is the branching fraction. Assuming f_{Ξ_{b}^{-}}/f_{Λ_{b}^{0}} is bounded between 0.1 and 0.3, the branching fraction B(Ξ_{b}^{-}→Λ_{b}^{0}π^{-}) would lie in the range from (0.57±0.21)% to (0.19±0.07)%.

Abstract:

The current status of flavour physics and the prospects for present and future experiments will be reviewed. Measurements in B-physics, in which sensitive probes of new physics are the CKM angle γ, the Bs mixing phase ϕs, and the branching ratios of the rare decays B(s)0→μ+μ- , will be highlighted. Topics in charm and kaon physics, in which the measurements of ACP and the branching ratios of the rare decays K→πνν¯ are key measurements, will be discussed. Finally the complementarity of the future heavy flavour experiments, the LHCb upgrade and Belle-II, will be summarised.