614 research outputs found

    Energy scan of the e+ehb(nP)π+πe^+e^- \to h_b(nP)\pi^+\pi^- (n=1,2)(n=1,2) cross sections and evidence for Υ(11020)\Upsilon(11020) decays into charged bottomonium-like states

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    Using data collected with the Belle detector at the KEKB asymmetric-energy e+ee^+e^- collider, we measure the energy dependence of the e+ehb(nP)π+πe^+e^- \to h_b(nP)\pi^+\pi^- (n=1,2)(n=1,2) cross sections from thresholds up to 11.0211.02\,GeV. We find clear Υ(10860)\Upsilon(10860) and Υ(11020)\Upsilon(11020) peaks with little or no continuum contribution. We study the resonant substructure of the Υ(11020)hb(nP)π+π\Upsilon(11020) \to h_b(nP)\pi^+\pi^- transitions and find evidence that they proceed entirely via the intermediate isovector states Zb(10610)Z_b(10610) and Zb(10650)Z_b(10650). The relative fraction of these states is loosely constrained by the current data: the hypothesis that only Zb(10610)Z_b(10610) is produced is excluded at the level of 3.3 standard deviations, while the hypothesis that only Zb(10650)Z_b(10650) is produced is not excluded at a significant level.Comment: 8 pages, 4 figures, submitted to Physical Review Letter

    First observation of the hadronic transition Υ(4S)ηhb(1P) \Upsilon(4S) \to \eta h_{b}(1P) and new measurement of the hb(1P)h_b(1P) and ηb(1S)\eta_b(1S) parameters

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    Using a sample of 771.6×106771.6 \times 10^{6} Υ(4S)\Upsilon(4S) decays collected by the Belle experiment at the KEKB e+ee^+e^- collider, we observe for the first time the transition Υ(4S)ηhb(1P)\Upsilon(4S) \to \eta h_b(1P) with the branching fraction B[Υ(4S)ηhb(1P)]=(2.18±0.11±0.18)×103{\cal B}[\Upsilon(4S) \to \eta h_b(1P)]= (2.18 \pm 0.11 \pm 0.18) \times 10^{-3} and we measure the hb(1P)h_b(1P) mass Mhb(1P)=(9899.3±0.4±1.0)M_{h_{b}(1P)} = (9899.3 \pm 0.4 \pm 1.0) MeV/c2c^{2}, corresponding to the hyperfine splitting ΔMHF(1P)=(0.6±0.4±1.0)\Delta M_{\mathrm HF}(1P) = (0.6 \pm 0.4 \pm 1.0) MeV/c2c^{2}. Using the transition hb(1P)γηb(1S)h_b(1P) \to \gamma \eta_b(1S), we measure the ηb(1S)\eta_b(1S) mass Mηb(1S)=(9400.7±1.7±1.6)M_{\eta_{b}(1S)} = (9400.7 \pm 1.7 \pm 1.6) MeV/c2c^{2}, corresponding to ΔMHF(1S)=(59.6±1.7±1.6)\Delta M_{\mathrm HF}(1S) = (59.6 \pm 1.7 \pm 1.6) MeV/c2c^{2}, the ηb(1S)\eta_b(1S) width Γηb(1S)=(85+6±5)\Gamma_{\eta_{b}(1S)} = (8 ^{+6}_{-5} \pm 5) MeV/c2c^{2} and the branching fraction B[hb(1P)γηb(1S)]=(56±8±4)%{\cal B}[h_b(1P) \to \gamma \eta_b(1S)]= (56 \pm 8 \pm 4) \%.Comment: 7 pages, 2 figures, submitted to Phys. Rev. Let

    Semi-inclusive studies of semileptonic BsB_s decays at Belle

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    We present an analysis of the semi-inclusive decays BsDsX+νB_s \to D_s^- X \ell^+ \nu and BsDsX+νB_s \to D_s^{*-} X \ell^+ \nu, where XX denotes a final state that may consist of additional hadrons or photons and \ell is an electron or muon. The studied BsB_s decays are contained in the 121.4 fb1121.4~{\rm fb}^{-1} Υ(5S)\Upsilon(5S) data sample collected by the Belle detector at the KEKB asymmetric-energy e+ee^+e^- collider. The branching fractions of the decays are measured to be B(BsDsX+ν)=[8.2±0.2(stat)±0.6(syst)±1.4(ext)]%\mathcal{B}(B_s \to D_s^- X \ell^+ \nu) = [8.2 \pm 0.2 (\text{stat}) \pm 0.6 (\text{syst}) \pm 1.4 (\text{ext})]\% and B(BsDsX+ν)=[5.4±0.4(stat)±0.4(syst)±0.9(ext)]%\mathcal{B}(B_s \to D_s^{*-} X \ell^+ \nu) = [5.4 \pm 0.4 (\text{stat}) \pm 0.4 (\text{syst}) \pm 0.9 (\text{ext})]\%, where the first two uncertainties are statistical and systematic and the last is due to external parameters. The measurement also provides an estimate of the Bs()Bˉs()B_s^{(*)}\bar{B}_s^{(*)} production cross-section, σ(e+eBs()Bˉs())=(53.8±1.4(stat)±4.0(syst)±3.4(ext))pb\sigma(e^+e^- \to B_s^{(*)}\bar{B}_s^{(*)}) = (53.8 \pm 1.4 (\text{stat}) \pm 4.0 (\text{syst}) \pm 3.4 (\text{ext}))\,{\rm pb}, at the center-of-mass energy s=10.86GeV\sqrt{s} = 10.86\,{\rm GeV}.Comment: 13 pages, 2 figures, submitted to Phys. Rev.

    Search for a massive invisible particle X0X^0 in B+e+X0B^{+}\to e^{+}X^{0} and B+μ+X0B^{+}\to \mu^{+}X^{0} decays

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    We present a search for a non-Standard-Model invisible particle X0X^0 in the mass range 0.1-1.8GeV/c20.1\textrm{-}1.8 \,{\rm GeV}/{c^2} in B+e+X0B^{+}\to e^{+} X^{0} and B+μ+X0B^{+}\to \mu^{+} X^{0} decays. The results are obtained from a 711 fb1711~{\rm fb}^{-1} data sample that corresponds to 772×106BBˉ772 \times 10^{6} B\bar{B} pairs, collected at the Υ(4S)\Upsilon(4S) resonance with the Belle detector at the KEKB e+ee^+ e^- collider. One BB meson is fully reconstructed in a hadronic mode to determine the momentum of the lepton of the signal decay in the rest frame of the recoiling partner BB meson. We find no evidence of a signal and set upper limits on the order of 10610^{-6}.Comment: 8 pages, 4 figures, 3 table

    High Resolution Model Intercomparison Project (HighResMIP v1.0) for CMIP6

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    Robust projections and predictions of climate variability and change, particularly at regional scales, rely on the driving processes being represented with fidelity in model simulations. The role of enhanced horizontal resolution in improved process representation in all components of the climate system is of growing interest, particularly as some recent simulations suggest the possibility for significant changes in both large-scale aspects of circulation, as well as improvements in small-scale processes and extremes. However, such high resolution global simulations at climate time scales, with resolutions of at least 50 km in the atmosphere and 0.25° in the ocean, have been performed at relatively few research centers and generally without overall coordination, primarily due to their computational cost. Assessing the robustness of the response of simulated climate to model resolution requires a large multi-model ensemble using a coordinated set of experiments. The Coupled Model Intercomparison Project 6 (CMIP6) is the ideal framework within which to conduct such a study, due to the strong link to models being developed for the CMIP DECK experiments and other MIPs. Increases in High Performance Computing (HPC) resources, as well as the revised experimental design for CMIP6, now enables a detailed investigation of the impact of increased resolution up to synoptic weather scales on the simulated mean climate and its variability. The High Resolution Model Intercomparison Project (HighResMIP) presented in this paper applies, for the first time, a multi-model approach to the systematic investigation of the impact of horizontal resolution. A coordinated set of experiments has been designed to assess both a standard and an enhanced horizontal resolution simulation in the atmosphere and ocean. The set of HighResMIP experiments is divided into three tiers consisting of atmosphere-only and coupled runs and spanning the period 1950-2050, with the possibility to extend to 2100, together with some additional targeted experiments. This paper describes the experimental set-up of HighResMIP, the analysis plan, the connection with the other CMIP6 endorsed MIPs, as well as the DECK and CMIP6 historical simulation. HighResMIP thereby focuses on one of the CMIP6 broad questions: “what are the origins and consequences of systematic model biases?”, but we also discuss how it addresses the World Climate Research Program (WCRP) grand challenges

    Study of e+e- => B(*) B(*)-bar pi+- at sqrt(s)=10.866 GeV

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    We report the analysis of the three-body e+e- => B B-bar pi, B B*-bar pi, and B* B*-bar pi processes, including the first observation of the Zb+-(10610) =>[B B*-bar+c.c.]+- and Zb+-(10650) => [B*B*-bar]+- transitions. We measure visible cross sections for the three-body production of sigma_vis(e+e- => [B B*-bar+c.c.]+-pi-+=(11.2+-1.0(stat.)+-1.2(syst.)) pb and sigma_vis(e+e- => [B*B*-bar]+-pi-+)=(5.61+-0.73(stat.)+-0.66(syst.)) pb and set a 90% C.L. upper limit of sigma_vis(e+e- => [BB-bar]+-pi-+)<2.1 pb. The results are based on a 121.4 1/fb data sample collected with the Belle detector at a center-of-mass energy near the Y(5S) peak.Comment: 8 pages, 2 figure

    Search for a dark vector gauge boson decaying to π+π\pi^+ \pi^- using ηπ+πγ\eta \rightarrow \pi^+\pi^- \gamma decays

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    We report a search for a dark vector gauge boson UU^\prime that couples to quarks in the decay chain D+D0π+,D0KS0η,ηUγD^{*+} \to D^0 \pi^+, D^0 \to K^0_S \eta, \eta \to U^\prime \gamma, Uπ+πU^\prime \to \pi^+ \pi^-. No signal is found and we set a mass-dependent limit on the baryonic fine structure constant of 10310210^{-3} - 10^{-2} in the UU^\prime mass range of 290 to 520 MeV/c2c^2. This analysis is based on a data sample of 976 fb1^{-1} collected by the Belle experiment at the KEKB asymmetric-energy e+ee^+e^- collider.Comment: 6 pages, 4 figure

    Studies of charmed strange baryons in the ΛD\Lambda D final state at Belle

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    We report the discovery of Ξc(3055)0\Xi_{c}(3055)^{0}, observed by its decay into the final state ΛD0\Lambda D^{0}, and present the first observation and evidence of the decays of Ξc(3055)+\Xi_c(3055)^{+} and Ξc(3080)+\Xi_c(3080)^{+} into ΛD+\Lambda D^{+}. We also perform a combined analysis of the ΛD+\Lambda D^{+} with the Σc++K\Sigma_{c}^{++}K^{-} and Σc++K\Sigma_{c}^{\ast ++}K^{-} decay modes to measure the ratios of branching fractions, masses and widths with improved accuracy. We measure the ratios of branching fractions B(Ξc(3055)+ΛD+)/B(Ξc(3055)+Σc++K)=5.09±1.01±0.76{\cal B}(\Xi_{c}(3055)^{+} \to \Lambda D^{+})/{\cal B}(\Xi_{c}(3055)^{+} \to \Sigma_{c}^{++}K^{-})=5.09\pm1.01\pm0.76, B(Ξc(3080)+ΛD+)/B(Ξc(3080)+Σc++K)=1.29±0.30±0.15{\cal B}(\Xi_{c}(3080)^{+} \to \Lambda D^{+})/{\cal B}(\Xi_{c}(3080)^{+} \to \Sigma_{c}^{++}K^{-})=1.29\pm0.30\pm0.15, and B(Ξc(3080)+Σc++K)/B(Ξc(3080)+Σc++K)=1.07±0.27±0.01{\cal B}(\Xi_{c}(3080)^{+} \to \Sigma_{c}^{\ast ++}K^{-})/{\cal B}(\Xi_{c}(3080)^{+} \to \Sigma_{c}^{++}K^{-})=1.07\pm0.27\pm0.01, where the uncertainties are statistical and systematic. The analysis is performed using a 980 fb1^{-1} data sample collected with the Belle detector at the KEKB asymmetric-energy e+ee^{+}e^{-} collider.Comment: Submitted to PR

    Measurement of the CP Violation Parameters in B0 -> pi+ pi- Decays

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    We present a measurement of the time-dependent charge-parity (CP) violation parameters in B0 -> pi+ pi- decays. The results are obtained from the final data sample containing 772 million BBbar pairs collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider. We obtain the CP violation parameters Acp = +0.33 +/- 0.06 (stat) +/- 0.03 (syst) and Scp = -0.64 +/- 0.08 (stat) +/- 0.03 (syst), where Acp and Scp represent the direct and mixing-induced CP asymmetry, respectively. Using an isospin analysis including results from other Belle measurements, we find 23.8 < phi2 < 66.8 degrees is disfavored at the 1 sigma level, where phi2 is one of the three interior angles of the CKM unitarity triangle related to B_{u,d} decays.Comment: 16 pages, 5 figures, CKM2012 conference paper, Submitted to PR
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