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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 An angular analysis of the B 0 → K *0 (→ K + π − ) μ + μ − decay is presented. The dataset corresponds to an integrated luminosity of 3.0 fb −1 of pp collision data collected at the LHCb experiment. The complete angular information from the decay is used to determine CP -averaged observables and CP asymmetries, taking account of possible contamination from decays with the K + π − system in an S-wave configuration. The angular observables and their correlations are reported in bins of q 2 , the invariant mass squared of the dimuon system. The observables are determined both from an unbinned maximum likelihood fit and by using the principal moments of the angular distribution. In addition, by fitting for q 2 -dependent decay amplitudes in the region 1.1 < q 2 < 6.0 GeV 2 / c 4 , the zero-crossing points of several angular observables are computed. A global fit is performed to the complete set of CP -averaged observables obtained from the maximum likelihood fit. This fit indicates differences with predictions based on the Standard Model at the level of 3.4 standard deviations. These differences could be explained by contributions from physics beyond the Standard Model, or by an unexpectedly large hadronic effect that is not accounted for in the Standard Model predictions.

A bstract Production cross-sections of prompt charm mesons are measured with the first data from pp collisions at the LHC at a centre-of-mass energy of 13 TeV. The data sample corresponds to an integrated luminosity of 4.98 ± 0.19 pb −1 collected by the LHCb experiment. The production cross-sections of D 0 , D + , D s + , and D *+ mesons are measured in bins of charm meson transverse momentum, p T , and rapidity, y , and cover the range 0 < p T < 15GeV/c and 2.0 < y < 4.5. The inclusive cross-sections for the four mesons, including charge conjugation, within the range of 1 < p T < 8 GeV/c are found to be σ pp → D 0 X = 2460 ± 3 ± 130 μ b σ pp → D + X = 1000 ± 3 ± 110 μ b σ pp → D s + X = 460 ± 13 ± 100 μ b σ pp → D ∗ + X = 880 ± 5 ± 140 μ b where the uncertainties are due to statistical and systematic uncertainties, respectively.

A bstract An angular analysis and a measurement of the differential branching fraction of the decay B s 0  →  ϕμ + μ − are presented, using data corresponding to an integrated luminosity of 3 . 0 fb −1 of pp collisions recorded by the LHCb experiment at s = 7 and 8 TeV. Measurements are reported as a function of q 2 , the square of the dimuon invariant mass and results of the angular analysis are found to be consistent with the Standard Model. In the range 1 < q 2 < 6 GeV 2 /c 4 , where precise theoretical calculations are available, the differential branching fraction is found to be more than 3 σ below the Standard Model predictions.

The objective of this work was to characterize a novel appearance defect found in Cheddar cheese, heretofore referred to as black spot defect (BSD), and to determine an etiology. Uniformly distributed throughout the cheese mass, BSD appears as small spherical black spots from 0.20 to 4.7mm in diameter and at an average frequency of about 2 spots per kg of cheese. To date, BSD has only been found in aged Cheddar cheese. Selected elemental analysis found the BSD region in cheese to have average concentrations of the element bismuth of approximately 400μg/g, representing an approximately 2,500-fold increase over native levels of bismuth in cheese. Transmission electron microscopy analysis of the BSD region revealed amorphous solid structures and one-dimensional hair-like structures, neither of which was present in non-BSD regions. Such amorphous “nanorod” structures can be formed by the crystallization of bismuth III sulfide and are proposed to be a source of black discoloration. We hypothesize that localized bismuth salts entrained within the cheese curd react with hydrogen sulfide generated during aging to generate bismuth III sulfide. We further propose that the presence of localized bismuth salt precursor results from residual levels of a commercial intra-mammary teat sealant containing bismuth subnitrate that becomes unintentionally entrained within the cheese milk.

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 A measurement of the production cross-section of Z bosons in pp collisions at s = 13 TeV is presented using dimuon and dielectron final states in LHCb data. The cross-section is measured for leptons with pseudorapidities in the range 2 . 0 < η < 4 . 5, transverse momenta p T > 20 GeV and dilepton invariant mass in the range 60 < m ( ℓℓ ) < 120 GeV. The integrated cross-section from averaging the two final states is σ Z ℓℓ  = 194.3 ± 0.9 ± 3.3 ± 7.6 pb , where the first uncertainty is statistical, the second is due to systematic effects, and the third is due to the luminosity determination. In addition, differential cross-sections are measured as functions of the Z boson rapidity, transverse momentum and the angular variable ϕ η * .

A bstract A measurement of the differential branching fraction of the decay B 0 → K ∗ (892) 0 μ + μ − is presented together with a determination of the S-wave fraction of the K + π − system in the decay B 0 → K + π − μ + μ − . The analysis is based on pp -collision data corresponding to an integrated luminosity of 3 fb −1 collected with the LHCb experiment. The measurements are made in bins of the invariant mass squared of the dimuon system, q 2 . Precise theoretical predictions for the differential branching fraction of B 0 → K ∗ (892) 0 μ + μ − decays are available for the q 2 region 1 . 1 < q 2 < 6 . 0 GeV 2 /c 4 . In this q 2 region, for the K + π − invariant mass range 796 < m Kπ < 996 MeV /c 2 , the S-wave fraction of the K + π − system in B 0 → K + π − μ + μ − decays is found to be F S = 0.101 ± 0.017 stat ± 0.009 syst , and the differential branching fraction of B 0 → K ∗ (892) 0 μ + μ − decays is determined to be d ℬ / d q 2 = 0 . 392 − 0.019 + 0.020 stat ± 0.010 syst ± 0.027 norm × 1 0 − 7 c 4 / GeV 2 . The differential branching fraction measurements presented are the most precise to date and are found to be in agreement with Standard Model predictions.

A bstract A measurement of the cross-section for W → eν production in pp collisions is presented using data corresponding to an integrated luminosity of 2 fb −1 collected by the LHCb experiment at a centre-of-mass energy of s = 8 TeV. The electrons are required to have more than 20 GeV of transverse momentum and to lie between 2 . 00 and 4 . 25 in pseudorapidity. The inclusive W production cross-sections, where the W decays to eν , are measured to be σ W + → e + ν e = 1124.4 ± 2.1 ± 21.5 ± 11.2 ± 13.0 p b , σ W − → e − ν ¯ e = 809.0 ± 1.9 ± 18.1 ± 7.0 ± 9.4 p b , where the first uncertainties are statistical, the second are systematic, the third are due to the knowledge of the LHC beam energy and the fourth are due to the luminosity determination. Differential cross-sections as a function of the electron pseudorapidity are measured. The W + /W − cross-section ratio and production charge asymmetry are also reported. Results are compared with theoretical predictions at next-to-next-to-leading order in perturbative quantum chromodynamics. Finally, in a precise test of lepton universality, the ratio of W boson branching fractions is determined to be ℬ W → e ν / ℬ W → μ ν = 1.020 ± 0.002 ± 0.019 , where the first uncertainty is statistical and the second is systematic.

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.