Measurement of the CKM angle γ from a combination of B±→Dh± analyses

A combination of three LHCb measurements of the CKM angle γ is presented. The decays B±→D K± and B±→Dπ± are used, where D denotes an admixture of D0 and D0 mesons, decaying into K+K−, π+π−, K±π∓, K±π∓π±π∓, K0Sπ+π−, or K0S K+K− final states. All measurements use a dataset corresponding to 1.0 fb−1 of integrated luminosity. Combining results from B±→D K± decays alone a best-fit value of γ =72.0◦ is found, and confidence intervals are set γ ∈ [56.4,86.7]◦ at 68% CL, γ ∈ [42.6,99.6]◦ at 95% CL. The best-fit value of γ found from a combination of results from B±→Dπ± decays alone, is γ =18.9◦, and the confidence intervals γ ∈ [7.4,99.2]◦ ∪ [167.9,176.4]◦ at 68% CL are set, without constraint at 95% CL. The combination of results from B± → D K± and B± → Dπ± decays gives a best-fit value of γ =72.6◦ and the confidence intervals γ ∈ [55.4,82.3]◦ at 68% CL, γ ∈ [40.2,92.7]◦ at 95% CL are set. All values are expressed modulo 180◦, and are obtained taking into account the effect of D0–D0 mixing

Precision measurement of D meson mass differences

Using three- and four-body decays of D mesons produced in semileptonic b-hadron decays, precision measurements of D meson mass differences are made together with a measurement of the D 0 mass. The measurements are based on a dataset corresponding to an integrated luminosity of 1.0 fb -1 collected in pp collisions at 7 TeV. Using the decay D 0 → K + K - K - π +, the D 0 mass is measured to be M(D0)=1864. 75± 0.15(stat)± 0.11(syst) MeV/c2. The mass differences M(D+)-M(D0=4.76± 0.12(stat)± MeV/c 2. M(Ds+)-M(D+)=98.68± 0.03(stat)± 0.04(syst) MeV/c2 are measured using the D 0 → K + K - π + π - and Ds+ to K+K -π+ modes. © 2013 CERN for the benefit of the LHCb collaboration