LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., Ruiz Valls, P., et al. (2016). Amplitude analysis of B- -> D+pi(-)pi(-) decays. Phys. Rev. D, 94(7), 072001–23pp.
Abstract: The Dalitz plot analysis technique is used to study the resonant substructures of B- -> D+pi(-)pi(-) decays in a data sample corresponding to 3.0 fb(-1) of pp collision data recorded by the LHCb experiment during 2011 and 2012. A model-independent analysis of the angular moments demonstrates the presence of resonances with spins 1, 2 and 3 at high D+pi(-) mass. The data are fitted with an amplitude model composed of a quasi-model-independent function to describe the D+pi(-) S wave together with virtual contributions from the D*(2007)(0) and B*(0) states, and components corresponding to the D-2*(2460)(0), D-1*(2680)(0), D-3*(2760)(0) and D-2*(3000)(0) resonances. The masses and widths of these resonances are determined together with the branching fractions for their production in B- -> D+pi(-)pi(-) decays. The D+pi(-) S wave has phase motion consistent with that expected due to the presence of the D-0*(2400)(0) state. These results constitute the first observations of the D-3*(2760)(0) and D-2*(3000)(0) resonances, with significances of 10 sigma and 6.6 sigma, respectively.
|
LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., Ruiz Valls, P., et al. (2016). Search for Structure in the B-s(0)pi(+/-) Invariant Mass Spectrum. Phys. Rev. Lett., 117(15), 152003–9pp.
Abstract: The B-s(0)pi(+/-) invariant mass distribution is investigated in order to search for possible exotic meson states. The analysis is based on a data sample recorded with the LHCb detector corresponding to 3 fb(-1) of pp collision data at root s 7 and 8 TeV. No significant excess is found, and upper limits are set on the production rate of the claimed X(5568) state within the LHCb acceptance. Upper limits are also set as a function of the mass and width of a possible exotic meson decaying to the B-s(0)pi(+/-) final state. The same limits also apply to a possible exotic meson decaying through the chain B-s(*0)pi(+/-), B-s(*0) -> B-s(0) gamma where the photon is excluded from the reconstructed decays.
|
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 forward W -> e nu production in pp collisions at root s=8 TeV. J. High Energy Phys., 10(10), 030–29pp.
Abstract: A measurement of the cross-section for W -> e nu 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 root 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 e nu, are measured to be W-sigma(+)-> e(+)nu(e)= 1124.4 +/- 2.1 +/- 21.5 +/- 11.2 +/- 13.0 pb, W-sigma(-)-> e(-)(nu) over bar (e) = 809.0 +/- 1.9 +/- 18.1 +/- 7.0 +/- 9.4 pb, 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 nu)/B(W -> μnu) = 1.020 +/- 0.002 +/- 0.019, where the first uncertainty is statistical and the second is systematic.
|
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.
|
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 CP Violation in B-0 -> D+D- Decays. Phys. Rev. Lett., 117(26), 261801–10pp.
Abstract: The CP violation observables S and C in the decay channel B-0 -> D+D- are determined from a sample of proton-proton collisions at center-of-mass energies of 7 and 8 TeV, collected by the LHCb experiment and corresponding to an integrated luminosity of 3 fb(-1). The observable S describes CP violation in the interference between mixing and the decay amplitude, and C parametrizes direct CP violation in the decay. The following values are obtained from a flavor-tagged, decay-time-dependent analysis: S = -0.54(-0.16)(+0.17) (stat) +/- 0.05(syst) ,C=0.26(-0.17)(+0.18) (stat) +/- 0.02(syst). These values provide evidence for CP violation at a significance level of 4.0 standard deviations. The phase shift due to higher-order standard model corrections is constrained to a small value of Delta phi = -0.16(-0.21)(+0.19) rad.
|
LHCb Collaboration(Aaij, R. et al), Garcia Martin, L. M., Martinez-Vidal, F., Oyanguren, A., Remon Alepuz, C., Ruiz Valls, P., et al. (2016). Study of B-c(+) decays to the K+K-pi(+) final state and evidence for the decay B-c(+) -> chi(c0)pi(+). Phys. Rev. D, 94(9), 091102–10pp.
Abstract: A study of B-c(+) -> K+K-pi(+) decays is performed for the first time using data corresponding to an integrated luminosity of 3.0 fb(-1) collected by the LHCb experiment in pp collisions at center-of-mass energies of 7 and 8 TeV. Evidence for the decay B-c(+) -> chi(c0)(K+K-)pi(+) is reported with a significance of 4.0 standard deviations, giving sigma(B-c(+))/sigma(B+) x B(B-c(+) -> chi(c0)pi+) = (9.8(-3.0)(+3.4)(stat) +/- 0.8(stat)) x 10(-6). Here B denotes a branching fraction while sigma(B-c(+)) and sigma(B+) are the production cross sections for B-c(+) and B+ mesons. An indication of (b) over barc weak annihilation is found for the region m(K-pi(+)) < 1.834 GeV/c(2), with a significance of 2.4 standard deviations.
|
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.
|
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.
|
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.
|
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)*.
|
