Measurement of the Bc-meson production fraction and asymmetry in 7 and 13 TeV pp collisions

The production fraction of the Bc-meson with respect to the sum of B- A nd B0 mesons is measured in both 7 and 13 TeV center-of-mass (c.m.) energy pp collisions produced by the Large Hadron Collider (LHC), using the LHCb detector. The rate, approximately 3.7 per mille, does not change with energy, but shows a transverse momentum dependence. The Bc-Bc+ production asymmetry is also measured and is consistent with zero within the determined statistical and systematic uncertainties of a few percent

Updated measurement of decay-time-dependent CP asymmetries in D-0 -> K+ K- and D-0 -> pi(+)pi(-) decays

A search for decay-time-dependent charge-parity (CP) asymmetry in D0→K+K− and D0→π+π− decays is performed at the LHCb experiment using proton-proton collision data recorded at a center-of-mass energy of 13 TeV, and corresponding to an integrated luminosity of 5.4  fb−1. The D0 mesons are required to originate from semileptonic decays of b hadrons, such that the charge of the muon identifies the flavor of the neutral D meson at production. The asymmetries in the effective decay widths of D0 and ¯D0 mesons are determined to be AΓ(K+K−)=(−4.3±3.6±0.5)×10−4 and AΓ(π+π−)=(2.2±7.0±0.8)×10−4, where the uncertainties are statistical and systematic, respectively. The results are consistent with CP symmetry and, when combined with previous LHCb results, yield AΓ(K+K−)=(−4.4±2.3±0.6)×10−4 and AΓ(π+π−)=(2.5±4.3±0.7)×10−4

Search for the Rare Decays B-s(0) -> e(+) e(-) and B-0 -> e(+) e(-)

A search for the decays B0s→e+e− and B0→e+e− is performed using data collected with the LHCb experiment in proton-proton collisions at center-of-mass energies of 7, 8, and 13 TeV, corresponding to integrated luminosities of 1, 2, and 2  fb−1, respectively. No signal is observed. Assuming no contribution from B0→e+e− decays, an upper limit on the branching fraction B(B0s→e+e−)<9.4(11.2)×10−9 is obtained at 90(95)% confidence level. If no B0s→e+e− contribution is assumed, a limit of B(B0→e+e−)<2.5(3.0)×10−9 is determined at 90(95)% confidence level. These upper limits are more than one order of magnitude lower than the previous values

Search for the lepton flavour violating decay B + → K + μ − τ + using Bs2∗0 decays

A search is presented for the lepton flavour violating decay B+ → K+μ−τ+ using a sample of proton-proton collisions at centre-of-mass energies of 7, 8, and 13 TeV, collected with the LHCb detector and corresponding to a total integrated luminosity of 9 fb−1. The τ leptons are selected inclusively, primarily via decays with a single charged particle. The four-momentum of the τ lepton is determined by using B+ mesons from B∗0s2→B+K− decays. No significant excess is observed, and an upper limit is set on the branching fractio

Precision measurement of the Ξcc++ mass

A measurement of the Ξ++cc mass is performed using data collected by the LHCb experiment between 2016 and 2018 in pp collisions at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 5.6 fb−1. The Ξ++cc candidates are reconstructed via the decay modes Ξ++cc→Λ+cK−π+π+ and Ξ++cc→Ξ+cπ+. The result, 3621.55 ± 0.23 (stat) ± 0.30 (syst) MeV/c2, is the most precise measurement of the Ξ++cc mass to date

Measurement of CP violation in B 0 → D ∗± D ∓ decays

The decay-time-dependent CP asymmetry in B0 → D∗±D∓ decays is mea- sured using a data set corresponding to an integrated luminosity of 9 fb−1 recorded by the LHCb detector in proton-proton collisions at centre-of-mass energies of 7, 8 and 13 TeV. The CP parameters are measured as SD∗D=−0.861±0.077(stat)±0.019(syst),ΔSD∗D=0.019±0.075(stat)±0.012(syst),CD∗D=−0.059±0.092(stat)±0.020(syst),ΔCD∗D=−0.031±0.092(stat)±0.016(syst),AD∗D=0.008±0.014(stat)±0.006(syst). The analysis provides the most precise single measurement of CP violation in this decay channel to date. All parameters are consistent with their current world average values

Precision measurement of the Bc+ meson mass

A precision measurement of the B+c meson mass is performed using proton- proton collision data collected with the LHCb experiment at centre-of-mass energies of 7, 8 and 13 TeV, corresponding to a total integrated luminosity of 9.0 fb−1. The B+c mesons are reconstructed via the decays B+c → J/ψπ+, B+c → J/ψπ+π−π+, B+c→J/ψpp¯¯¯π+, B+c→J/ψD+s, B+c → J/ψ D0K+ and B+c→B0sπ+. Combining the results of the individual decay channels, the B+c mass is measured to be 6274.47 ± 0.27 (stat) ± 0.17 (syst) MeV/c2. This is the most precise measurement of the B+c mass to date. The difference between the B+c and B0s meson masses is measured to be 907.75 ± 0.37 (stat) ± 0.27 (syst) MeV/c

Measurement of the Λb0 → J/ψΛ angular distribution and the Λb0 polarisation in pp collisions

This paper presents an analysis of the Λ0b→ J/ψΛ angular distribution and the transverse production polarisation of Λ0b baryons in proton-proton collisions at centre-of-mass energies of 7, 8 and 13 TeV. The measurements are performed using data corresponding to an integrated luminosity of 4.9 fb−1, collected with the LHCb experiment. The polarisation is determined in a fiducial region of Λ0b transverse momentum and pseudorapidity of 1 < pT < 20 GeV/c and 2 < η < 5, respectively. The data are consistent with Λ0b baryons being produced unpolarised in this region. The parity-violating asymmetry parameter of the Λ → pπ− decay is also determined from the data and its value is found to be consistent with a recent measurement by the BES III collaboration

Measurement of CP observables in B ± → DK ± and B ± → Dπ ± with D → KS0K±π∓ decays

Measurements of CP observables in B± → DK± and B± → Dπ± decays are presented, where D represents a superposition of D0 and D¯¯¯¯0 states. The D meson is reconstructed in the three-body final states K0SK±π∓ and K0SK∓π±. The analysis uses samples of B mesons produced in proton-proton collisions, corresponding to an integrated luminosity of 1.0, 2.0, and 6.0 fb−1 collected with the LHCb detector at centre-of-mass energies of s√ = 7, 8, and 13 TeV, respectively. These measurements are the most precise to date, and provide important input for the determination of the CKM angle γ

Observation of a new baryon state in the Λb0π+π− mass spectrum

A new baryon state is observed in the Λ0bπ+π− mass spectrum with high significance using a data sample of pp collisions, collected with the LHCb detector at centre-of-mass energies s√ = 7, 8 and 13 TeV, corresponding to an integrated luminosity of 9 fb−1. The mass and natural width of the new state are measured to be m=6072.3±2.9±0.6±0.2 MeV,Γ=72±11±2 MeV, where the first uncertainty is statistical and the second systematic. The third uncertainty for the mass is due to imprecise knowledge of the Λ0b baryon mass. The new state is consistent with the first radial excitation of the Λ0b baryon, the Λb(2S)0 resonance. Updated measurements of the masses and the upper limits on the natural widths of the previously observed Λb(5912)0 and Λb(5920)0 states are also reported