Abstract: The production cross-sections of J/psi mesons in proton-proton collisions at a centre-of-mass energy of root s = 5TeV are measured using a data sample corresponding to an integrated luminosity of 9.13 +/- 0.18 pb(-1), collected by the LHCb experiment. The cross-sections are measured differentially as a function of transverse momentum, p(T), and rapidity, y, and separately for J/psi mesons produced promptly and from beauty hadron decays (nonprompt). With the assumption of unpolarised J/psi mesons, the production cross-sections integrated over the kinematic range 0 < p(T) < 20 GeV/c and 2.0 < y < 4.5 are sigma(prompt) J/psi = 8.154 +/- 0.010 +/- 0.283 μb, sigma(nonprompt) J/psi = 0.820 +/- 0.003 +/- 0.034 μb, where the first uncertainties are statistical and the second systematic. These cross-sections are compared with those at root s = 8TeV and 13TeV, and are used to update the measurement of the nuclear modification factor in proton-lead collisions for J/psi mesons at a centre-of-mass energy per nucleon pair of root s(NN) = 5TeV. The results are compared with theoretical predictions.

Abstract: A binned Dalitz plot analysis of B-+/- -> DK +/- decays, with D -> K-S(0) pi(+)pi(-) and D -> K0 S K + K -, is performed to measure the C P -violating observables x(+/-) and y(+/-), which are sensitive to the Cabibbo-Kobayashi-Maskawa angle gamma. The analysis exploits a sample of proton-proton collision data corresponding to 3.0 fb(-1) collected by the LHCb experiment. Measurements from CLEO-c of the variation of the strong-interaction phase of the D decay over the Dalitz plot are used as inputs. The values of the parameters are found to be x(+) = (-7.7 +/- 2.4 +/- 1.0 +/- 0.4) x 10(-2), x(-) = (2.5 +/- 2.5 +/- 1.0 +/- 0.5) x 10(-2), y(+) = (-2.2 +/- 2.5 +/- 0.4 +/- 1.0) x 10-2, and y(-) = (7.5 +/- 2.9 +/- 0.5 +/- 1.4) x 10(-2). The first, second, and third uncertainties are the statistical, the experimental systematic, and that associated with the precision of the strong-phase parameters. These are the most precise measurements of these observables and correspond to +/- = (62(-14)(+15))degrees, with a second solution at gamma -> gamma + 180 degrees, and r(B) = 0.080(-0.021)(+0.019), where r(B) is the ratio between the suppressed and favoured B decay amplitudes.

Abstract: First observations of the rare decays B (+) -> K (+)pi (+) pi (-) μ(+) μ(-) and B (+)-> phi K+ mu(+)mu(-) are presented using data corresponding to an integrated luminosity of 3.0 fb(-1), collected by the LHCb experiment at centre-of-mass energies of 7 and 8 TeV. The branching fractions of the decays are B(B (+) -> K (+)pi (+) pi (-) μ(+) μ(-) ) = (4.36 (-0.27) (+0.29) (stat) +/- 0.21 (syst) +/- (norm)) x 10(-7), B(B (+)-> phi K+ mu(+)mu(-)) = (0.82 (+0.19)(-0.17) (stat) (+0.10)(-0.04) (syst) +/- 0.27 (norm)) x 10(-7) where the uncertainties are statistical, systematic, and due to the uncertainty on the branching fractions of the normalisation modes. A measurement of the differential branching fraction in bins of the invariant mass squared of the dimuon system is also presented for the decay B (+) -> K (+)pi (+) pi (-) μ(+) μ(-)

Abstract: The determination of track reconstruction efficiencies at LHCb using J/psi -> mu(+)mu(-) decays is presented. Efficiencies above 95% are found for the data taking periods in 2010, 2011, and 2012. The ratio of the track reconstruction efficiency of muons in data and simulation is compatible with unity and measured with an uncertainty of 0.8% for data taking in 2010, and at a precision of 0.4% for data taking in 2011 and 2012. For hadrons an additional 1.4% uncertainty due to material interactions is assumed. This result is crucial for accurate cross section and branching fraction measurements in LHCb.

Abstract: Using a dataset corresponding to an integrated luminosity of 3.0 fb(-1) collected in pp collisions at centre-of-mass energies of 7 and 8 TeV, the B (s) (0) -> aEuro parts per thousand I center dot I center dot branching fraction is measured to be B(B-0 -> phi phi) = (1.84 +/- 0.05(stat) +/- 0.07 (syst) +/- 0.11 (f(s)/f(d)) +/- 0.12 (norm)) x 10(-5) where f (s) /f (d) represents the ratio of the B (s) (0) to B (0) production cross-sections, and the B (0) -> I center dot K (*)(892)(0) decay mode is used for normalization. This is the most precise measurement of this branching fraction to date, representing a factor five reduction in the statistical uncertainty compared with the previous best measurement. A search for the decay B (0) -> I center dot I center dot is also made. No signal is observed, and an upper limit on the branching fraction is set as B(B-0 -> phi phi < 2.8 x 10(-8)) at 90% confidence level. This is a factor of seven improvement compared to the previous best limit.