Differential branching fraction and angular analysis of the decay B 0 → K * 0 μ + μ -
Journal of High Energy Physics 2013:8 (2013)
Abstract:
The angular distribution and differential branching fraction of the decay B 0→ K * 0 μ + μ - are studied using a data sample, collected by the LHCb experiment in pp collisions at S=7 TeV, corresponding to an integrated luminosity of 1.0 fb -1. Several angular observables are measured in bins of the dimuon invariant mass squared, q 2. A first measurement of the zero-crossing point of the forward-backward asymmetry of the dimuon system is also presented. The zero-crossing point is measured to be q02=4.9± 0.9 GeV2 c4, where the uncertainty is the sum of statistical and systematic uncertainties. The results are consistent with the Standard Model predictions. [Figure not available: see fulltext.] © 2013 Cern for the benefit of the LHCb collaboration.Search for the lepton-flavor-violating decays Bs0→e ±μ and B0→e±μ
Physical Review Letters 111:14 (2013)
Abstract:
A search for the lepton-flavor-violating decays Bs0→e ±μ and B0→e±μ is performed with a data sample, corresponding to an integrated luminosity of 1.0 fb-1 of pp collisions at √s=7 TeV, collected by the LHCb experiment. The observed number of Bs0→e±μ and B0→e ±μ candidates is consistent with background expectations. Upper limits on the branching fractions of both decays are determined to be B(Bs0→e±μ)<1.1(1.4)×10-8 and B(B0→e±μ)<2.8(3.7)×10-9 at 90% (95%) confidence level (C.L.). These limits are a factor of 20 lower than those set by previous experiments. Lower bounds on the Pati-Salam leptoquark masses are also calculated, MLQ(Bs0→e±μ)>101 TeV/c2 and MLQ(B0→e±μ)>126 TeV/c2 at 95% C.L., and are a factor of 2 higher than the previous bounds. © 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.Study of D J meson decays to D + π − , D 0 π + and D* + π − final states in pp collisions
Journal of High Energy Physics 2013:9 (2013)
Abstract:
A study of D + π − , D 0 π + and D* + π − final states is performed using πcollision data, corresponding to an integrated luminosity of 1.0 fb −1 , collected at a centre-of-mass energy of 7 TeV with the LHCb detector. The D 1 (2420) 0 resonance is observed in the D* + π − final state and the D* 2 (2460) resonance is observed in the D + π − , D 0 π + and D* + π − final states. For both resonances, their properties and spin-parity assignments are obtained. In addition, two natural parity and two unnatural parity resonances are observed in the mass region between 2500 and 2800 MeV. Further structures in the region around 3000 MeV are observed in all the D* + π − , D + π − and D 0 π + final states.Measurement of D0-D0bar mixing parameters and search for CP violation using D0->K+pi- decays
ArXiv 1309.6534 (2013)
Abstract:
Measurements of charm mixing parameters from the decay-time-dependent ratio of D0->K+pi- to D0->K-pi+ rates and the charge-conjugate ratio are reported. The analysis uses data, corresponding to 3 fb^{-1} of integrated luminosity, from proton-proton collisions at 7 and 8 TeV center-of-mass energies recorded by the LHCb experiment. In the limit of charge-parity (CP) symmetry, the mixing parameters are determined to be x'^2=(5.5 +- 4.9)x10^{-5}, y'= (4.8 +- 1.0)x10^{-3}, and R_D=(3.568 +- 0.066)x10^{-3}. Allowing for CP violation, the mixing parameters are determined separately for D0 and D0bar mesons yielding A_D = (-0.7 +- 1.9)%, for the direct CP-violating asymmetry, and 0.75 < |q/p|< 1.24 at the 68.3% confidence level, where q and p are parameters that describe the mass eigenstates of the neutral charm mesons in terms of the flavor eigenstates. This is the most precise determination of these parameters from a single experiment and shows no evidence for CP violation.Studies of the decays B+→pp̄h+ and observation of B+→Λ̄(1520)p
Physical Review D - Particles, Fields, Gravitation and Cosmology 88:5 (2013)