Observation of the suppressed Λ0b→DpK− decay with D→K+π− and measurement of its CP asymmetry

A study of Λ0b baryon decays to the DpK− final state is presented based on a proton-proton collision data sample corresponding to an integrated luminosity of 9  fb−1 collected with the LHCb detector. Two Λ0b decays are considered, Λ0b→DpK− with D→K−π+ and D→K+π−, where D represents a superposition of D0 and ¯D0 states. The latter process is expected to be suppressed relative to the former, and is observed for the first time. The ratio of branching fractions of the two decays is measured, and the CP asymmetry of the suppressed mode, which is sensitive to the Cabibbo-Kobayashi-Maskawa angle γ, is also reported

Simultaneous determination of CKM angle γ and charm mixing parameters

A combination of measurements sensitive to the CP violation angle γ of the Cabibbo-Kobayashi-Maskawa unitarity triangle and to the charm mixing parameters that describe oscillations between D0 and D¯¯¯¯D¯0 mesons is performed. Results from the charm and beauty sectors, based on data collected with the LHCb detector at CERN's Large Hadron Collider, are combined for the first time. This method provides an improvement on the precision of the charm mixing parameter y by a factor of two with respect to the current world average. The charm mixing parameters are determined to be x=(0.400+0.052−0.053)%x=(0.400−0.053+0.052)% and y = (0.630+0.033−0.030)%(0.630−0.030+0.033)%. The angle γ is found to be γ = (65.4+3.8−4.2)∘(65.4−4.2+3.8)∘ and is the most precise determination from a single experiment

Observation of a Λb0 − Λ¯b0 production asymmetry in proton-proton collisions at √s = 7 and 8 TeV

This article presents differential measurements of the asymmetry between Λb0 and Λ¯b0 baryon production rates in proton-proton collisions at centre-of-mass energies of √s = 7 and 8 TeV collected with the LHCb experiment, corresponding to an integrated luminosity of 3 fb−1. The Λb0 baryons are reconstructed through the inclusive semileptonic decay Λb0 → Λc+μ−ν¯¯μX. The production asymmetry is measured both in intervals of rapidity in the range 2.15 < y < 4.10 and transverse momentum in 2 < pT < 27 GeV/c. The results are found to be incompatible with symmetric production with a significance of 5.8 standard deviations for both √s = 7 and 8 TeV data, assuming no CP violation in the decay. There is evidence for a trend as a function of rapidity with a significance of 4 standard deviations. Comparisons to predictions from hadronisation models in PYTHIA and heavy-quark recombination are provided. This result constitutes the first observation of a particle-antiparticle asymmetry in b-hadron production at LHC energies

Updated search for B+cBc+ decays to two charm mesons

A data set corresponding to an integrated luminosity of 9 fb−1 of proton-proton collisions collected by the LHCb experiment has been analysed to search for B+c→D(∗)+(s)(---)D(∗)0Bc+→D(s)(∗)+(---)D(∗)0 decays. The decays are fully or partially reconstructed, where one or two missing neutral pions or photons from the decay of an excited charm meson are allowed. Upper limits for the branching fractions, normalised to B+ decays to final states with similar topologies, are obtained for sixteen B+cBc+ decay modes. For the decay B+c→D+sD¯¯¯¯0Bc+→Ds+D¯0, an excess with a significance of 3.4 standard deviations is found

Angular analysis of the rare decay B0s → ϕμ+μ−

An angular analysis of the rare decay B0s → ϕμ+μ− is presented, using proton-proton collision data collected by the LHCb experiment at centre-of-mass energies of 7, 8 and 13 TeV, corresponding to an integrated luminosity of 8.4 fb−1. The observables describing the angular distributions of the decay B0s → ϕμ+μ− are determined in regions of q2, the square of the dimuon invariant mass. The results are consistent with Standard Model predictions

Angular analysis of the rare decay B s 0 → ϕμ + μ −

An angular analysis of the rare decay Bs0→ ϕμ+μ− is presented, using proton-proton collision data collected by the LHCb experiment at centre-of-mass energies of 7, 8 and 13 TeV, corresponding to an integrated luminosity of 8.4 fb−1. The observables describing the angular distributions of the decay Bs0→ ϕμ+μ− are determined in regions of q2, the square of the dimuon invariant mass. The results are consistent with Standard Model predictions

J/ψ and D0 production in sNN−−−√=68.5GeV PbNe collisions

The first measurement of J/ψ and D0 production in PbNe collisions by the LHCb experiment in its fixed-target configuration is reported. The production of J/ψ and D0 mesons is studied with a beam of lead ions with an energy of 2.5TeV per nucleon colliding on gaseous neon targets at rest, corresponding to a nucleon-nucleon centre-of-mass energy of sNN−−−√=68.5GeV. The J/ψ/D0 production cross-section ratio is studied as a function of rapidity, transverse momentum and collision centrality. These data are compared with measurements from pNe collisions at the same energy and show no difference in the observed J/ψ suppression trend when comparing pNe and PbNe peripheral collisions with PbNe central collisions