1,286 research outputs found

    Observation of Two Resonant Structures in e+e- to pi+ pi- psi(2S) via Initial State Radiation at Belle

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    The cross section for e+e- to pi+ pi- psi(2S) between threshold and \sqrt{s}=5.5 GeV is measured using 673 fb^{-1} of data on and off the \Upsilon(4S) resonance collected with the Belle detector at KEKB. Two resonant structures are observed in the pi+ pi- psi(2S) invariant mass distribution, one at 4361\pm 9\pm 9 MeV/c2 with a width of 74\pm 15\pm 10 MeV/c2, and another at 4664\pm 11\pm 5 MeV/c2 with a width of 48\pm 15\pm 3 MeV/c2, if the mass spectrum is parameterized with the coherent sum of two Breit-Wigner functions. These values do not match those of any of the known charmonium states.Comment: 10 pages, 5 figures, 2 tables, version to appear in Phys. Rev. Let

    Dalitz analysis of B --> K pi psi' decays and the Z(4430)+

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    From a Dalitz plot analysis of B --> K pi psi' decays, we find a signal for Z(4430)+ --> pi+ psi' with a mass M= (4443(+15-12)(+19-13))MeV/c^2, width Gamma= (107(+86-43)(+74-56))MeV, product branching fraction BR(B0 --> K- Z(4430)+) x BR(Z(4430)+ --> pi+ psi')= (3.2(+1.8-0.9)(+5.3-1.6)) x 10^{-5}, and significance of 6.4sigma that agrees with previous Belle measurements based on the same data sample. In addition, we determine the branching fraction BR(B^0 --> K*(892)^0 psi')= (5.52(+0.35-0.32)(+0.53-0.58)) x 10^{-4} and the fraction of K*(892)^0 mesons that are longitudinally polarized f_L= 44.8(+4.0-2.7)(+4.0-5.3)%. These results are obtained from a 605fb^{-1} data sample that contains 657 million B-anti-B pairs collected near the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric energy e+e- collider.Comment: Final version published in PRD(RC

    Measurements of Charmless Hadronic b->s Penguin Decays in the pi+pi-K+pi- Final State and First Observation of B0 -> rho0K+pi-

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    We report measurements of charmless hadronic B^0 decays into the pi+pi-K+pi+ final state. The analysis uses a sample of 657x10^6 BBbar pairs collected with the Belle detector at the KEKB asymmetric-energy e+e- collider at the Y(4S) resonance. The decay B^0 -> rho0 Kpi is observed for the first time; the significance is 5.0sigma and the corresponding partial branching fraction for M_Kpi in (0.75,1.20) GeV/c^2 is [2.8 +- 0.5(stat) +-0.5(syst)] x 10^{-6}. We also obtain the first evidence for B^0 -> f0Kpi with 3.5sigma significance and for B^0 -> pi+pi-K*0 with 4.5sigma significance. For the two-body decays B^0 -> rho0K*0 and B^0 -> f0K*0, the significances are 2.7sigma and 2.5sigma, respectively, and the upper limits on the branching fractions are 3.4x10^{-6} and 2.2x10^{-6} at 90% confidence level.Comment: 6 pages, 3 figures. accepted by PRD(RC

    Time-dependent CP Asymmetries in B0→KS0ρ0ÎłB^0\to K^0_S\rho^0\gamma Decays

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    We report the first measurement of CP-violation parameters in B^0 -> K_S^0\rho^0\gamma decays based on 657 million B\bar B pairs collected with the Belle detector at the KEKB asymmetric-energy collider. We measure the time-dependent CP violating parameter S_{K_S^0\rho^0\gamma}= 0.11 +/- 0.33(stat.)^{+0.05}_{-0.09}(syst.). We also obtain the effective direct CP violating parameter A_eff=0.05 +/- 0.18(stat.) +/- 0.06(syst.) for m_{K_S\pi^+\pi^-}<1.8 GeV/c^2 and 0.6 GeV/c^2<m_{\pi^+\pi^-}<0.9 GeV/c^2.Comment: 6 pages, 3 figures, to be submitted to PR

    Improved measurement of time-dependent CP violation in B0 -> J/Psi pi0 decays

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    We report improved measurements of time-dependent CP violation parameters for B0(Bˉ0)→J/ψπ0B^0(\bar{B}^0) \to J/\psi \pi^0 decay. This analysis is based on 535 million BBˉB\bar{B} pairs accumulated at the ΄(4S)\Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e^+e^- collider. From the distribution of proper time intervals between the two B decays, we obtain the following CP violation parameters SJ/ψπ0=−0.65±0.21(stat)±0.05(syst)\mathcal{S}_{J/\psi \pi^0} = -0.65\pm0.21 (\rm{stat})\pm0.05 (\rm{syst}) and AJ/ψπ0=+0.08±0.16(stat)±0.05(syst)\mathcal{A}_{J/\psi \pi^0} = +0.08\pm0.16 (\rm{stat})\pm0.05 (\rm{syst}), which are consistent with Standard Model expectations.Comment: Resubmitted to PRD(RC), including 4 figures, 6pages Revision has been made according to communication with PRD referee

    Observation of a new D_sJ meson in B+->D0BD0K+ decays

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    We report the observation of a new DsJD_{sJ} meson produced in B+→Dˉ0DsJ→Dˉ0D0K+B^{+} \to \bar{D}^{0} D_{sJ} \to \bar{D}^{0} D^{0} K^{+}. This state has a mass of M=2708±9−10+11MeV/c2M=2708 \pm 9 ^{+11}_{-10} \rm{MeV}/{\it c}^{2}, a width Γ=108±23−31+36 MeV/c2\Gamma = 108 \pm 23 ^{+36}_{-31} ~\rm{MeV}/ {\it c}^{2} and a 1−1^{-} spin-parity. The results are based on an analysis of 449 million BBˉB\bar{B} events collected at the ΄(4S)\Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e−e^{+} e^{-} collider.Comment: submitted to Phys. Rev. Let

    Structure and Instabilities of an Irradiated Viscous Protoplanetary Disk

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    We investigate the structure and the stabilities of a protoplanetary disk, which is heated by viscous process in itself and by its central star. The disk is set to rotate with the Keplerian velocity and has the surface density distribution of the minimum mass solar nebula. We assume the vertical hydrostatic equilibrium and the radiative equilibrium at each point, and solve the two-dimensional radiative transfer equation by means of the Short Characteristic method in the spherical coordinate in order to determine the disk structure. Our calculation shows that at the outer region of the disk with a distance from the central star of x>1AU the radiative heating from the inner disk dominates the viscous heating even near the midplane. It is because of the high temperature distribution in the optically thin surface layer and the relatively high disk height as a consequence of the irradiation from the inner hot region of the disk. In addition, we examine the convective and the magnetorotational instabilities of the disk. As a result, the whole disk is convectively stable since the dusty region is not heated by the viscous dissipation from the midplane but by the radial radiative heating. On the other hand, almost all the disk is magnetorotationally unstable except for the region near the equatorial plane of from 2AU to 10AU. Finally we discuss the growth and the size distribution of dust particles in the disk, which suggests that there exist cm-sized particles in the surface layer, namely, in the exposed region of the disk.Comment: 23 pages, 5 figures, accepted by ApJ (Vol. 567, 2002

    Evidence for B0→χc1π0B^0 \to \chi_{c1} \pi ^0 at Belle

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    We present a measurement of the branching fraction for the Cabibbo- and color-suppressed B0→χc1π0B^0 \to \chi_{c1}\pi^0 decay based on a data sample of 657×106657\times 10^6 BBˉB\bar B events collected at the ΄(4S)\Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e−e^+e^- collider. We observe a signal of 40±940\pm9 events with a significance of 4.7σ4.7\sigma including systematic uncertainties. The measured branching fraction is B(B0→χc1π0)=(1.12±0.25(stat.)±0.12(syst.))×10−5\mathcal {B}(B^0 \to \chi_{c1} \pi^0) = (1.12\pm 0.25(\rm {stat.})\pm 0.12({\rm syst.}))\times 10^{-5}.Comment: 5 pages, 5 figure
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