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A bstract A test of lepton universality, performed by measuring the ratio of the branching fractions of the B 0 → K *0 μ + μ − and B 0 → K *0 e + e − decays, R K * 0 , is presented. The K *0 meson is reconstructed in the final state K + π − , which is required to have an invariant mass within 100 MeV /c 2 of the known K * (892) 0 mass. The analysis is performed using proton-proton collision data, corresponding to an integrated luminosity of about 3 fb −1 , collected by the LHCb experiment at centre-of-mass energies of 7 and 8 TeV. The ratio is measured in two regions of the dilepton invariant mass squared, q 2 , to be R K * 0 = 0.66 − + 0.07 0.11 stat ± 0.03 syst f o r 0.045 < q 2 < 1.1 GeV 2 / c 4 , 0.69 − + 0.07 0.11 stat ± 0.05 syst f o r 1.1 < q 2 < 6.0 GeV 2 / c 4 . The corresponding 95.4% confidence level intervals are [0 . 52 , 0 . 89] and [0 . 53 , 0 . 94]. The results, which represent the most precise measurements of R K * 0 to date, are compatible with the Standard Model expectations at the level of 2.1–2.3 and 2.4–2.5 standard deviations in the two q 2 regions, respectively.

A bstract The production of ϒ ( nS ) mesons ( n = 1, 2, 3) in p Pb and Pb p collisions at a centre-of-mass energy per nucleon pair s N N = 8.16 TeV is measured by the LHCb experiment, using a data sample corresponding to an integrated luminosity of 31.8 nb −1 . The ϒ ( nS ) mesons are reconstructed through their decays into two opposite-sign muons. The measurements comprise the differential production cross-sections of the ϒ (1 S ) and ϒ (2 S ) states, their forward-to-backward ratios and nuclear modification factors. The measurements are performed as a function of the transverse momentum p T and rapidity in the nucleon-nucleon centre-of-mass frame y * of the ϒ ( nS ) states, in the kinematic range p T < 25 GeV/ c and 1.5 < y * < 4.0 (−5.0 < y * < −2.5) for p Pb (Pb p ) collisions. In addition, production cross-sections for ϒ (3 S ) are measured integrated over phase space and the production ratios between all three ϒ ( nS ) states are determined. Suppression for bottomonium in proton-lead collisions is observed, which is particularly visible in the ratios. The results are compared to theoretical models.

A bstract The prompt production of Λ c + baryons is studied in proton-lead collisions collected with the LHCb detector at the LHC. The data sample corresponds to an integrated luminosity of 1.58 nb −1 recorded at a nucleon-nucleon centre-of-mass energy of s N N = 5.02 TeV. Measurements of the differential cross-section and the forwardbackward production ratio are reported for Λ c + baryons with transverse momenta in the range 2 < p T < 10 GeV/c and rapidities in the ranges 1.5 < y ∗ < 4.0 and −4.5 < y ∗ < −2.5 in the nucleon-nucleon centre-of-mass system. The ratio of cross-sections of Λ c + baryons and D 0 mesons is also reported. The results are compared with next-to-leading order calculations that use nuclear parton distribution functions.

A bstract The inclusive D s ± production asymmetry is measured in pp collisions collected by the LHCb experiment at centre-of-mass energies of s = 7 and 8 TeV. Promptly produced D s ± mesons are used, which decay as D s ±  →  ϕ π ± , with ϕ  →  K + K − . The measurement is performed in bins of transverse momentum, p T , and rapidity, y , covering the range 2 . 5 < p T < 25 . 0 GeV/c and 2 . 0 < y < 4 . 5. No kinematic dependence is observed. Evidence of nonzero D s ± production asymmetry is found with a significance of 3.3 standard deviations.

A bstract A search for CP and P violation using triple-product asymmetries is performed with Λ b 0  →  pK − π + π − , Λ b 0  →  pK − K + K − and Ξ b 0  →  pK − K − π + decays. The data sample corresponds to integrated luminosities of 1.0 fb −1 and 2.0 fb −1 , recorded with the LHCb detector at centre-of-mass energies of 7 TeV and 8 TeV, respectively. The CP - and P - violating asymmetries are measured both integrating over all phase space and in specific phase-space regions. No significant deviation from CP or P symmetry is found. The first observation of Λ b 0  →  pK − χ c0 (1 P )(→ π + π − ,  K + K − ) decay is also reported.

A bstract A search for charmless four-body decays of Λ b 0 and Ξ b 0 baryons with a proton and three charged mesons (either kaons or pions) in the final state is performed. The data sample used was recorded in 2011 and 2012 with the LHCb experiment and corresponds to an integrated luminosity of 3 fb −1 . Six decay modes are observed, among which Λ b 0  →  pK − π + π − , Λ b 0  →  pK − K + K − , Ξ b 0  →  pK − π + π − and Ξ b 0  →  pK − π + K − are established for the first time. Their branching fractions (including the ratio of hadronisation fractions in the case of the Ξ b 0 baryon) are determined relative to the Λ b 0  →  Λ c + π − decay.

A bstract A search for B +  →  D s + K + K − decays is performed using pp collision data corresponding to an integrated luminosity of 4.8 fb −1 , collected at centre-of-mass energies of 7, 8 and 13 TeV with the LHCb experiment. A significant signal is observed for the first time and the branching fraction is determined to be ℬ B + → D s + K + K − = 7.1 ± 0.5 ± 0.6 ± 0.7 × 1 0 − 6 , where the first uncertainty is statistical, the second systematic and the third due to the uncertainty on the branching fraction of the normalisation mode B + → D s + D ¯ 0 . A search is also performed for the pure annihilation decay B +  →  D s + ϕ . No significant signal is observed and a limit of ℬ B + → D s + ϕ < 4.9 × 1 0 − 7 4.2 × 1 0 − 7 is set on the branching fraction at 95% (90%) confidence level.

A precision measurement of the$$ {B}_c^{+} $$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$$ {B}_c^{+} $$B c + mesons are reconstructed via the decays$$ {B}_c^{+} $$B c + → J/ψπ + ,$$ {B}_c^{+} $$B c + → J/ψπ + π − π + ,$$ {B}_c^{+}\\to J/\\psi p\\overline{p}{\\pi}^{+} $$B c + → J / ψp p ¯ π + ,$$ {B}_c^{+}\\to J/\\psi {D}_s^{+} $$B c + → J / ψ D s + ,$$ {B}_c^{+} $$B c + → J/ψ D 0 K + and$$ {B}_c^{+}\\to {B}_s^0{\\pi}^{+} $$B c + → B s 0 π + . Combining the results of the individual decay channels, the$$ {B}_c^{+} $$B c + mass is measured to be 6274 . 47 ± 0 . 27 (stat) ± 0 . 17 (syst) MeV /c 2 . This is the most precise measurement of the$$ {B}_c^{+} $$B c + mass to date. The difference between the$$ {B}_c^{+} $$B c + and$$ {B}_s^0 $$B s 0 meson masses is measured to be 907 . 75 ± 0 . 37 (stat) ± 0 . 27 (syst) MeV /c .

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$$ {B}_{s2}^{\\ast 0}\\to {B}^{+}{K}^{-} $$B s 2 ∗ 0 → B + K − decays. No significant excess is observed, and an upper limit is set on the branching fraction ℬ( B +  →  K + μ − τ + ) < 3.9 × 10 −5  at 90 %  confidence level. The obtained limit is comparable to the world-best limit.

This paper presents an analysis of the \\( Λ_(b)⁰ \\){<}{/}{s}pan>→ J/ψΛ angular distribution and the transverse production polarisation of \\( Λ_(b)⁰ \\){<}{/}{s}pan> 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 \\( Λ_(b)⁰ \\){<}{/}{s}pan> transverse momentum and pseudorapidity of 1 < pT < 20 GeV/c and 2 < η < 5, respectively. The data are consistent with \\( Λ_(b)⁰ \\){<}{/}{s}pan> 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.