Sneha Malde

Abstract:

The time-dependent CP asymmetry in Bs0→J/ψK+K - decays is measured using pp collision data at √s=7 TeV, corresponding to an integrated luminosity of 1.0 fb-1, collected with the LHCb detector. The decay-time distribution is characterized by the decay widths ΓL and ΓH of the light and heavy mass eigenstates of the Bs0-B̄s0 system and by a CP-violating phase s. In a sample of 27 617 Bs0→J/ψK+K- decays, where the dominant contribution comes from Bs0→J/ψ decays, these parameters are measured to be s=0.07±0.09(stat) ±0.01(syst) rad, Γs≡(ΓL+Γ H)/2=0.663±0.005(stat)±0.006(syst) ps-1, and ΔΓs≡ΓL-ΓH=0. 100±0.016(stat)±0.003(syst) ps-1, corresponding to the single most precise determination of s, ΔΓs, and Γs. The result of performing a combined analysis with Bs0→J/ψπ+π- decays gives s=0.01±0.07(stat)±0.01(syst) rad, Γs= 0.661±0.004(stat)±0.006(syst) ps-1, and ΔΓs=0.106±0.011(stat)±0.007(syst) ps -1. All measurements are in agreement with the Standard Model predictions. © 2013 CERN. Published by the American Physical Society under the terms of the http://creativecommons.org/licenses/by/3.0/ Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

Abstract:

First observations of the BS0→ψ(2S)η, B0→ψ(2S)π+π- and BS0→ψ(2S)π+π- decays are made using a dataset corresponding to an integrated luminosity of 1.0 fb-1 collected by the LHCb experiment in proton-proton collisions at a centre-of-mass energy of √s=7 TeV. The ratios of the branching fractions of each of the ψ(2S) modes with respect to the corresponding J/ψ decays are where the third uncertainty corresponds to the uncertainties of the dilepton branching fractions of the J/ψ and ψ(2S) meson decays. © 2013 CERN.

Abstract:

The first observation of the decay Bs0→D̄0K -π+ is reported. The analysis is based on a data sample, corresponding to an integrated luminosity of 1.0 fb-1 of pp collisions, collected with the LHCb detector. The branching fraction relative to that of the topologically similar decay B0→D̄0π +π- is measured to be B(Bs0→D ̄0K-π+)B(B0→D ̄0π+π-)=1.18±0.05(stat) ±0.12(syst). In addition, the relative branching fraction of the decay B0→D̄0K+π- is measured to be B(B0→D̄0K+π-)B(B0→D ̄0π+π-)=0.106±0.007(stat) ±0.008(syst). © 2013 CERN. Published by the American Physical Society under the terms of the http://creativecommons.org/licenses/by/3.0/ Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.

Abstract:

The production cross-sections of B mesons are measured in pp collisions at a centre-of-mass energy of 7 TeV, using data collected with the LHCb detector corresponding to a integrated luminosity of 0.36 fb-1. The B+, B0 and Bs0 mesons are reconstructed in the exclusive decays B+ -> J/psi K+, B0 -> J/psi K*0 and Bs0 -> J/psi phi, with J/psi -> mu+ mu-, K*0 -> K+ pi- and phi -> K+ K-. The differential cross-sections are measured as functions of B meson transverse momentum pT and rapidity y, in the range 0 < pT < 40 GeV/c and 2.0 < y < 4.5. The integrated cross-sections in the same pT and y ranges, including charge-conjugate states, are measured to be sigma(pp -> B+ + X) = 38.9 +- 0.3 (stat.) +- 2.5 (syst.) +- 1.3 (norm.) mub, sigma(pp -> B0 + X) = 38.1 +- 0.6 (stat.) +- 3.7 (syst.) +- 4.7 (norm.) mub, sigma(pp -> Bs0 + X) = 10.5 +- 0.2 (stat.) +- 0.8 (syst.) +- 1.0 (norm.) mub, where the third uncertainty arises from the pre-existing branching fraction measurements.

Abstract:

The branching fractions of the decay B+ → pp K+ for different intermediate states are measured using data, corresponding to an integrated luminosity of 1.0 fb−1, collected by the LHCb experiment. The total branching fraction, its charmless component (Mpp < 2.85 GeV/c2) and the branching fractions via the resonant cc states ηc(1S) and ψ(2S) relative to the decay via a J/ψ intermediate state are B(B+ → pp K+) total/B(B+ → J/ψK+ →pp K+) = 4.91 ± 0.19 (stat) ± 0.14 (syst), B(B+ → pp K+)Mpp < 2.85 GeV/c2/B(B+ → J/ψK+ → pp K+) = 2.02 ± 0.10 (stat) ± 0.08 (syst), B(B+ → ηc(1S)K+ → pp K+)/B(B+ → J/ψK+ → pp K+) = 0.578 ± 0.035 (stat) ± 0.027 (syst), B(B+ → ψ(2S)K+ → pp K+)/B(B+ → J/ψK+ → pp K+) = 0.080 ± 0.012 (stat) ± 0.009 (syst). Upper limits on the B+ branching fractions into the ηc(2S) meson and into the charmonium-like states X(3872) and X(3915) are also obtained.