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LHCb Collaboration(Aaij, R. et al), Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., Ruiz Valls, P., & Sanchez Mayordomo, C. (2016). Measurements of the S-wave fraction in B-0 -> K+ pi(-) mu(+) mu(-) decays and the B-0 -> K*(892)(0) mu(+) mu(-) differential branching fraction. J. High Energy Phys., 11(11), 047–30pp.
Abstract: A measurement of the differential branching fraction of the decay B-0 -> K* (892)(0) mu(+)mu(-) is presented together with a determination of the S-wave fraction of the K+ pi(-) system in the decay B-0 -> K+ pi-mu(+)mu(-). 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) mu(+) mu(-) decays are available for the q(2) region 1.1 < q(2) < 6.0 GeV2/c(4). In this q(2) region, for the K+pi(-) invariant mass range 796 < m(K pi) < 996MeV/c(2), the S-wave fraction of the K+pi(-) system in B-0 -> K+pi(-)mu(+)mu(-) 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) mu(+)mu(-) decays is determined to be dB/dq(2) = (0.392(-0.019)(+ 0.020)(stat) +/- 0.010(syst) +/- 0.027(norm)) x 10(-7) c(4)/GeV2. The differential branching fraction measurements presented are the most precise to date and are found to be in agreement with Standard Model predictions.
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LHCb Collaboration(Aaij, R. et al), Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., Ruiz Valls, P., & Sanchez Mayordomo, C. (2016). Search for Higgs-like bosons decaying into long-lived exotic particles. Eur. Phys. J. C, 76(12), 664–15pp.
Abstract: A search is presented for massive long-lived particles, in the 20-60 GeV/c(2) mass range with lifetimes between 5 and 100 ps. The dataset used corresponds to 0.62 fb(-1) of proton-proton collision data collected by the LHCb detector at root s = 7 TeV. The particles are assumed to be pair-produced by the decay of a Higgs-like boson with mass between 80 and 140 GeV/c(2). No excess above the background expectation is observed and limits are set on the production cross-section as a function of the long-lived particle mass and lifetime and of the Higgs-like boson mass.
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LHCb Collaboration(Aaij, R. et al), Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., Ruiz Valls, P., & Sanchez Mayordomo, C. (2016). Measurement of the ratio of branching fractions B(B-c(+) -> J/psi K+)/B(B-c(+) -> J/psi pi(+)). J. High Energy Phys., 09(9), 153–15pp.
Abstract: The ratio of branching fractions R-K/pi = B (B-c(+) -> J/psi K+)/B(B-c(+) -> J/psi pi(+)) is measured with pp collision data collected by the LHCb experiment at centre-of-mass energies of 7TeV and 8TeV, corresponding to an integrated luminosity of 3 fb(-1). It is found to be R-K/pi = 0.079 +/- 0.007 +/- 0.003, where the first uncertainty is statistical and the second is systematic. This measurement is consistent with the previous LHCb result, while the uncertainties are significantly reduced.
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LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., Ruiz Valls, P., et al. (2016). Measurement of the CKM angle gamma from a combination of LHCb results. J. High Energy Phys., 12(12), 087–59pp.
Abstract: A combination of measurements sensitive to the CKM angle gamma from LHCb is performed. The inputs are from analyses of time-integrated B+ -> DK+, B-0 -> DK*(0), B-0 -> DK+ pi(-) and B+ -> DK+ pi(+) pi(-) tree-level decays. In addition, results from a time-dependent analysis of B-s(0) -> (DsK +/-)-K--/+ decays are included. The combination yields = (72: 2(-7.3)(+6:8) 7 : 3)degrees, where the uncertainty includes systematic effects. The 95.5% confidence level interval is determined to be gamma is an element of [55.9, 85.2]degrees. A second combination is investigated, also including measurements from B+ -> DK+, B-0 -> DK*(0), B-0 -> DK+ pi(-) and B+ -> DK+ pi(+) pi decays, which yields compatible results.
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LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., Ruiz Valls, P., et al. (2016). Measurement of the forward Z boson production cross-section in pp collisions at root s=13 TeV. J. High Energy Phys., 09(9), 136–33pp.
Abstract: A measurement of the production cross-section of Z bosons in pp collisions at root 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 < eta < 4.5, transverse momenta pT > 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 sigma(ll)(Z) = 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 phi(eta)*.
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LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., Ruiz Valls, P., et al. (2017). Observation of B+ -> J/psi 3 pi(+)2 pi(-) and B+ -> psi (2S)pi(+)pi(+)pi(-) decays. Eur. Phys. J. C, 77(2), 72–12pp.
Abstract: The decays B+-> J/psi 3 pi(+)2 pi(-) and B+ -> psi(2S)pi(+)pi(+)pi(-) are observed for the first time using a data sample corresponding to an integrated luminosity of 3.0 fb(-1), collected by the LHCb experiment in proton- proton collisions at the centre-of-mass energies of 7 and 8 TeV. The branching fractions relative to that of B+ -> psi(2S)K+ are measured to be B(B+-> J/psi 3 pi(+)2 pi(-))/B(B+ -> psi (2S)K+) = (1.88 +/- 0.17 +/- 0.09)x10(-2). B(B+ -> psi(2S)pi(+)pi(+)pi(-))/B(B+ -> psi (2S)K+) = (3.04 +/- 0.50 +/- 0.26)X10(-2) where the first uncertainties are statistical and the second are systematic.
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LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., Ruiz Valls, P., et al. (2017). Search for decays of neutral beauty mesons into four muons. J. High Energy Phys., 03(3), 001–19pp.
Abstract: A search for the non-resonant decays B-s(0) -> mu(+) mu(-) mu(+)mu(-) and B-0 -> mu(+) mu(-) mu(+) mu(-) is presented. The measurement is performed using the full Run 1 data set collected in proton-proton collisions by the LHCb experiment at the LHC. The data correspond to integrated luminosities of 1 and 2 fb(-1) collected at centre-of-mass energies of 7 and 8 TeV, respectively. No signal is observed and upper limits on the branching fractions of the non-resonant decays at 95% confidence level are determined to be B(B-s(0) -> mu(+) mu(-) mu(+)mu(-)) < 2.5 x 10(-9) B(B-0 -> mu(+) mu(-) mu(+) mu(-)) < 6.9 x 10(-10)
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Botella, F. J., Garcia Martin, L. M., Marangotto, D., Martinez-Vidal, F., Merli, A., Neri, N., et al. (2017). On the search for the electric dipole moment of strange and charm baryons at LHC. Eur. Phys. J. C, 77(3), 181–15pp.
Abstract: Permanent electric dipole moments (EDMs) of fundamental particles provide powerful probes for physics beyond the Standard Model. We propose to search for the EDM of strange and charm baryons at LHC, extending the ongoing experimental program on the neutron, muon, atoms, molecules and light nuclei. The EDM of strange. baryons, selected from weak decays of charm baryons produced in pp collisions at LHC, can be determined by studying the spin precession in the magnetic field of the detector tracking system. A test of CPT symmetry can be performed by measuring the magnetic dipole moment of. and. baryons. For short-lived Lambda(+)(c) and Xi(+)(c) baryons, to be produced in a fixedtarget experiment using the 7 TeV LHC beam and channeled in a bent crystal, the spin precession is induced by the intense electromagnetic field between crystal atomic planes. The experimental layout based on the LHCb detector and the expected sensitivities in the coming years are discussed.
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LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., Ruiz Valls, P., et al. (2017). Measurement of the phase difference between short- and long-distance amplitudes in the B+ -> K+ mu(+) mu(-) decay. Eur. Phys. J. C, 77(3), 161–15pp.
Abstract: A measurement of the phase difference between the short- and long-distance contributions to the decay is performed by analysing the dimuon mass distribution. The analysis is based on pp collision data corresponding to an integrated luminosity of 3 collected by the LHCb experiment in 2011 and 2012. The long-distance contribution to the decay is modelled as a sum of relativistic Breit-Wigner amplitudes representing different vector meson resonances decaying to muon pairs, each with their own magnitude and phase. The measured phases of the and resonances are such that the interference with the short-distance component in dimuon mass regions far from their pole masses is small. In addition, constraints are placed on the Wilson coefficients, and , and the branching fraction of the short-distance component is measured.
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LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., Ruiz Valls, P., et al. (2017). Observation of the suppressed decay Lambda(0)(b) -> p pi(-) mu(+) mu(-). J. High Energy Phys., 04(4), 029–16pp.
Abstract: The suppressed decay Lambda(0)(b) -> p pi(-) mu(+) mu(-), excluding the J/psi and psi(2S) -> mu(+) mu(-) resonances, is observed for the first time with a significance of 5.5 standard deviations. The analysis is performed with proton- proton collision data corresponding to an integrated luminosity of 3 fb(-1) collected with the LHCb experiment. The Lambda(0)(b) -> p pi(-) mu(+) mu(-) branching fraction is measured relative to the Lambda(0)(b) -> J/psi (-> mu(+) mu(-)) p pi(-) branching fraction giving B (Lambda(0)(b) -> p pi(-) mu(+) mu(-))/B(Lambda(0)(b) -> J/psi (-> mu(+) mu(-)) p pi(-)) = 0.044 +/- 0.012 +/- 0.007, where the first uncertainty is statistical and the second is systematic. This is the first observation of a b -> d transition in a baryonic decay.
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