1,791 research outputs found

    Study of BDKπ+πB^{-}\to DK^-\pi^+\pi^- and BDππ+πB^-\to D\pi^-\pi^+\pi^- decays and determination of the CKM angle γ\gamma

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    We report a study of the suppressed BDKπ+πB^-\to DK^-\pi^+\pi^- and favored BDππ+πB^-\to D\pi^-\pi^+\pi^- decays, where the neutral DD meson is detected through its decays to the Kπ±K^{\mp}\pi^{\pm} and CP-even K+KK^+K^- and π+π\pi^+\pi^- final states. The measurement is carried out using a proton-proton collision data sample collected by the LHCb experiment, corresponding to an integrated luminosity of 3.0~fb1^{-1}. We observe the first significant signals in the CP-even final states of the DD meson for both the suppressed BDKπ+πB^-\to DK^-\pi^+\pi^- and favored BDππ+πB^-\to D\pi^-\pi^+\pi^- modes, as well as in the doubly Cabibbo-suppressed DK+πD\to K^+\pi^- final state of the BDππ+πB^-\to D\pi^-\pi^+\pi^- decay. Evidence for the ADS suppressed decay BDKπ+πB^{-}\to DK^-\pi^+\pi^-, with DK+πD\to K^+\pi^-, is also presented. From the observed yields in the BDKπ+πB^-\to DK^-\pi^+\pi^-, BDππ+πB^-\to D\pi^-\pi^+\pi^- and their charge conjugate decay modes, we measure the value of the weak phase to be γ=(7419+20)o\gamma=(74^{+20}_{-19})^{\rm o}. This is one of the most precise single-measurement determinations of γ\gamma to date.Comment: 22 pages, 9 figures; All figures and tables, along with any supplementary material and additional information, are available at https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2015-020.htm

    Observation of an Excited Bc+ State

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    Using pp collision data corresponding to an integrated luminosity of 8.5 fb-1 recorded by the LHCb experiment at center-of-mass energies of s=7, 8, and 13 TeV, the observation of an excited Bc+ state in the Bc+π+π- invariant-mass spectrum is reported. The observed peak has a mass of 6841.2±0.6(stat)±0.1(syst)±0.8(Bc+) MeV/c2, where the last uncertainty is due to the limited knowledge of the Bc+ mass. It is consistent with expectations of the Bc∗(2S31)+ state reconstructed without the low-energy photon from the Bc∗(1S31)+→Bc+γ decay following Bc∗(2S31)+→Bc∗(1S31)+π+π-. A second state is seen with a global (local) statistical significance of 2.2σ (3.2σ) and a mass of 6872.1±1.3(stat)±0.1(syst)±0.8(Bc+) MeV/c2, and is consistent with the Bc(2S10)+ state. These mass measurements are the most precise to date

    Amplitude analysis of B0Dˉ0K+πB^0 \rightarrow \bar{D}^0 K^+ \pi^- decays

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    The Dalitz plot distribution of B0Dˉ0K+πB^0 \rightarrow \bar{D}^0 K^+ \pi^- decays is studied using a data sample corresponding to 3.0fb13.0\rm{fb}^{-1} of pppp collision data recorded by the LHCb experiment during 2011 and 2012. The data are described by an amplitude model that contains contributions from intermediate K(892)0K^*(892)^0, K(1410)0K^*(1410)^0, K2(1430)0K^*_2(1430)^0 and D2(2460)D^*_2(2460)^- resonances. The model also contains components to describe broad structures, including the K0(1430)0K^*_0(1430)^0 and D0(2400)D^*_0(2400)^- resonances, in the KπK\pi S-wave and the DπD\pi S- and P-waves. The masses and widths of the D0(2400)D^*_0(2400)^- and D2(2460)D^*_2(2460)^- resonances are measured, as are the complex amplitudes and fit fractions for all components included in the amplitude model. The model obtained will be an integral part of a future determination of the angle γ\gamma of the CKM quark mixing matrix using B0DK+πB^0 \rightarrow D K^+ \pi^- decays.Comment: 33 pages, 12 figures; updated for publicatio

    Study of WW boson production in association with beauty and charm

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    The associated production of a WW boson with a jet originating from either a light parton or heavy-flavor quark is studied in the forward region using proton-proton collisions. The analysis uses data corresponding to integrated luminosities of 1.0 and 2.0fb12.0\,{\rm fb}^{-1} collected with the LHCb detector at center-of-mass energies of 7 and 8 TeV, respectively. The WW bosons are reconstructed using the WμνW\to\mu\nu decay and muons with a transverse momentum, pTp_{\rm T}, larger than 20 GeV in the pseudorapidity range 2.0202.0 20 GeV and 2.2<η<4.22.2 < \eta < 4.2. The sum of the muon and jet momenta must satisfy pT>20p_{\rm T} > 20 GeV. The fraction of W+W+jet events that originate from beauty and charm quarks is measured, along with the charge asymmetries of the W ⁣+ ⁣bW\!+\!b and W ⁣+ ⁣cW\!+\!c production cross-sections. The ratio of the W+W+jet to Z+Z+jet production cross-sections is also measured using the ZμμZ\to\mu\mu decay. All results are in agreement with Standard Model predictions

    Measurement of the Bs0J/ψηB_{s}^{0} \rightarrow J/\psi \eta lifetime

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    Using a data set corresponding to an integrated luminosity of 3fb13 fb^{-1}, collected by the LHCb experiment in pppp collisions at centre-of-mass energies of 7 and 8 TeV, the effective lifetime in the Bs0J/ψηB^0_s \rightarrow J/\psi \eta decay mode, τeff\tau_{\textrm{eff}}, is measured to be τeff=1.479±0.034 (stat)±0.011 (syst)\tau_{\textrm{eff}} = 1.479 \pm 0.034~\textrm{(stat)} \pm 0.011 ~\textrm{(syst)} ps. Assuming CPCP conservation, τeff\tau_{\textrm{eff}} corresponds to the lifetime of the light Bs0B_s^0 mass eigenstate. This is the first measurement of the effective lifetime in this decay mode.Comment: All figures and tables, along with any supplementary material and additional information, are available at https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2016-017.htm

    Observation of J/ψpJ/\psi p resonances consistent with pentaquark states in Λb0J/ψKp{\Lambda_b^0\to J/\psi K^-p} decays

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    Observations of exotic structures in the J/ψpJ/\psi p channel, that we refer to as pentaquark-charmonium states, in Λb0J/ψKp\Lambda_b^0\to J/\psi K^- p decays are presented. The data sample corresponds to an integrated luminosity of 3/fb acquired with the LHCb detector from 7 and 8 TeV pp collisions. An amplitude analysis is performed on the three-body final-state that reproduces the two-body mass and angular distributions. To obtain a satisfactory fit of the structures seen in the J/ψpJ/\psi p mass spectrum, it is necessary to include two Breit-Wigner amplitudes that each describe a resonant state. The significance of each of these resonances is more than 9 standard deviations. One has a mass of 4380±8±294380\pm 8\pm 29 MeV and a width of 205±18±86205\pm 18\pm 86 MeV, while the second is narrower, with a mass of 4449.8±1.7±2.54449.8\pm 1.7\pm 2.5 MeV and a width of 39±5±1939\pm 5\pm 19 MeV. The preferred JPJ^P assignments are of opposite parity, with one state having spin 3/2 and the other 5/2.Comment: 48 pages, 18 figures including the supplementary material, v2 after referee's comments, now 19 figure
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