153 research outputs found

    Measurement of ϕ\phi(1020) meson leptonic width with CMD-2 detector at VEPP-2M Collider

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    The ϕ\phi(1020) meson leptonic width has been determined from the combined analysis of 4 major decay modes of the resonance (ϕK+K,KL0KS0,π+ππ0,ηγ\phi\to K^+ K^-,K^0_LK^0_S,\pi^+\pi^-\pi^0,\eta\gamma) studied with the CMD-2 detector at the VEPP-2M e+ee^+e^- collider. The following value has been obtained: Γ(ϕe+e)=1.235±0.006±0.022\Gamma(\phi\to e^+e^-) = 1.235\pm 0.006\pm 0.022 keV. The ϕ(1020)\phi(1020) meson parameters in four main decay channels have been also recalculated: B(ϕK+K)=0.493±0.003±0.007B(\phi\to K^+K^-) = 0.493\pm 0.003\pm 0.007, B(ϕKLKS)=0.336±0.002±0.006B(\phi\to K_LK_S) = 0.336\pm 0.002\pm 0.006, B(ϕπ+ππ0)=0.155±0.002±0.005B(\phi\to\pi^+\pi^-\pi^0) = 0.155\pm 0.002\pm 0.005, B(ϕηγ)=0.0138±0.0002±0.0002B(\phi\to\eta\gamma) = 0.0138\pm 0.0002\pm 0.0002.Comment: 14 pages, 3 figure

    Study of the radiative decay ϕηγ\phi \to \eta \gamma with CMD-2 detector

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    Using the 1.9pb11.9 pb^{-1} of data collected with the CMD-2 detector at VEPP-2M the decay mode ϕηγ\phi \to \eta \gamma, ηπ+ππ0\eta \to \pi^+\pi^-\pi^0 has been studied. The obtained branching ratio is B(ϕηγ)=(1.18±0.03±0.06)\phi \to \eta \gamma) = (1.18 \pm 0.03 \pm 0.06) %.Comment: 13 pages, 5 figures, LaTex2e, to be published in Phys. Lett.

    Observation of KS0K_S^0 semileptonic decays with CMD-2 detector

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    The decay KS0πeνK_S^0 \to \pi e \nu has been observed by the CMD-2 detector at the e^+e^- collider VEPP-2M at Novosibirsk. Of 6 million produced KL0KS0K_L^0K_S^0 pairs, 75±1375 \pm 13 events of the KS0πeνK_S^0 \to \pi e \nu decay were selected. The corresponding branching ratio is B(KS0πeν)=(7.2±1.4)×104B(K_S^0 \to \pi e \nu)=(7.2 \pm 1.4)\times10^{-4}. This result is consistent with the evaluation of B(KS0πeν)B(K_S^0 \to \pi e \nu) from the KL0K_L^0 semileptonic rate and KS0K_S^0 lifetime assuming ΔS=ΔQ\Delta S=\Delta Q .Comment: 7 pages, 6 figures, LaTex2e. Submitted to Phys.Lett.

    Measurement of omega meson parameters in pi^+pi^-pi^0 decay mode with CMD-2

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    About 11 200 e^+e^- -> omega -> pi^+pi^-pi^0 events selected in the center of mass energy range from 760 to 810 MeV were used for the measurement of the \omega meson parameters. The following results have been obtained: sigma _{0}=(1457 \pm 23 \pm 19)nb, m_{\omega}=(782.71 \pm 0.07 \pm 0.04) MeV/c^{2}, \Gamma_{\omega}=(8.68 \pm 0.23 \pm 0.10) MeV, \Gamma_{e^+e^-}\cdot Br (\omega -> pi^+pi^-pi^0)= (0.528 \pm 0.012 \pm 0.007) \cdot 10^{-3} MeV.Comment: 8 pages, 4 figure

    Study of the Process e+eKL0KS0e^+e^- \to K^0_L K^0_S in the C.M.Energy Range 1.05-1.38 GeV with CMD-2

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    The process e+eKL0KS0e^+e^- \to K^0_L K^0_S has been studied with the CMD-2 detector using about 950 events detected in the center-of-mass energy range from 1.05 to 1.38 GeV. The cross section exceeds the expectation based on the contributions of the rho(770), omega(782) and phi(1020) mesons only.Comment: 12 pages, 3 figures, uses elsart.cls, submitted to Physics Letters

    Cross section of the reaction e+eπ+ππ+πe^+ e^- \to \pi^+\pi^-\pi^+\pi^- below 1 GeV at CMD-2

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    Using 3.07 pb1{pb}^{-1} of data collected in the energy range 0.60-0.97 GeV by CMD-2, about 150 events of the process \epm \to \pch have been selected. The energy dependence of the cross section agrees with the assumption of the a1(1260)πa_1(1260) \pi intermediate state which is dominant above 1 GeV. For the first time \fourpi events are observed at the ρ\rho meson energy. Under the assumption that all these events come from the ρ\rho meson decay, the value of the cross section at the ρ\rho meson peak corresponds to the following decay width: \Gamma(\rho^0 \to \fourpi) = (2.8 \pm 1.4 \pm 0.5) {keV} or to the branching ratio B(\rho^0 \to \fourpi) = (1.8 \pm 0.9 \pm 0.3) \cdot 10 ^{-5}.Comment: 15 pages, 5 figure

    Study of KS KL Coupled Decays and KL -Be Interactions with the CMD-2 Detector at VEPP-2M Collider

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    The integrated luminosity about 4000 inverse nanobarn of around phi meson mass ( 5 millions of phi mesons) has been collected with the CMD-2 detector at the VEPP-2M collider. A latest analysis of the KS KL coupled decays based on 30 % of available data is presented in this paper. The KS KL pairs from phi meson decays were reconstructed in the drift chamber when both kaons decayed into two charged particles. From a sample of 1423 coupled decays a selection of candidates to the CP violating KL into pi+ pi- decay was performed. CP violating decays were not identified because of the domination of events with a KL regenerating at the Be beam pipe into KS and a background from KL semileptonic decays. The regeneration cross section of 110 MeV/c KL mesons was found to be 53 +- 17 mb in agreement with theoretical expectations. The angular distribution of KS mesons after regeneration and the total cross section of KL for Be have been measured.Comment: 14 pages, 8 figure
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