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)
Abstract:
Dynamics and direct CP violation in three-body charmless decays of charged B mesons to a proton, an antiproton and a light meson (pion or kaon) are studied using data, corresponding to an integrated luminosity of 1.0 fb-1, collected by the LHCb experiment in pp collisions at a center-of-mass energy of 7 TeV. Production spectra are determined as a function of Dalitz-plot and helicity variables. The forward-backward asymmetry of the light meson in the pp̄ rest frame is measured. No significant CP asymmetry in B +→pp̄K+ decay is found in any region of the Dalitz plane. We present the first observation of the decay B +→Λ̄(1520)(→K+p̄)p near the K+p̄ threshold and measure B(B+→Λ̄ (1520)p)=(3.9-0.9+1.0(stat)±0.1(syst)±0.3(BF))×10 -7, where BF denotes the uncertainty on secondary branching fractions. © 2013 CERN. Published by the American Physical Society under the terms of the.Observation of a resonance in B+→K+μ +μ- decays at low recoil
Physical Review Letters 111:11 (2013)