4,606 research outputs found

    Observation of Bs0J/ψf0(980)B_s^0\to J/\psi f_0(980) and Evidence for Bs0J/ψf0(1370)B_s^0\to J/\psi f_0(1370)

    Full text link
    We report the first observation of Bs0J/ψf0(980)B_s^0\to J/\psi f_0(980) and first evidence for Bs0J/ψf0(1370)B_s^0\to J/\psi f_0(1370), which are CP eigenstate decay modes. These results are obtained from 121.4  fb1121.4\;\mathrm{fb}^{-1} of data collected at the Υ(5S)\Upsilon(5S) resonance with the Belle detector at the KEKB e+ee^+e^- collider. We measure the branching fractions B(Bs0J/ψf0(980);f0(980)π+π)=(1.160.19+0.31(stat.)0.17+0.15(syst.)0.18+0.26(NBs()Bˉs()))×104\mathcal{B}(B_s^0\to J/\psi f_0(980);f_0(980)\to\pi^+\pi^-)=(1.16^{+0.31}_{-0.19}(\mathrm{stat.})^{+0.15}_{-0.17}(\mathrm{syst.})^{+0.26}_{-0.18}(N_{B_s^{(*)}\bar B_s^{(*)}})) \times 10^{-4} with a significance of 8.4σ8.4\sigma, and B(Bs0J/ψf0(1370);f0(1370)π+π)=(0.340.14+0.11(stat.)0.02+0.03(syst.)0.05+0.08(NBs()Bˉs()))×104\mathcal{B}(B_s^0\to J/\psi f_0(1370);f_0(1370)\to\pi^+\pi^-)=(0.34^{+0.11}_{-0.14}(\mathrm{stat.})^{+0.03}_{-0.02}(\mathrm{syst.})^{+0.08}_{-0.05}(N_{B_s^{(*)}\bar B_s^{(*)}})) \times 10^{-4} with a significance of 4.2σ4.2\sigma. The last error listed is due to uncertainty in the number of produced Bs()Bˉs()B_s^{(*)}\bar B_s^{(*)} pairs.Comment: 5 pages, 2 figures, 2 tables, published in PR

    Measurement of eta_c(1S), eta_c(2S) and non-resonant eta' pi+ pi- production via two-photon collisions

    Full text link
    We report the measurement of gamma gamma to eta_c(1S), eta_c(2S) to eta' pi+ pi- with eta' decays to gamma rho and eta pi+ pi- using 941 fb^{-1} of data collected with the Belle detector at the KEKB asymmetric-energy e+e- collider. The eta_c(1S) mass and width are measured to be M = [2984.6\pm0.7 (stat.)\pm2.2 (syst.)] MeV/c^{2} and \Gamma = [30.8^{+2.3}_{-2.2}~(stat.) \pm 2.5~(syst.)] MeV, respectively. First observation of eta_c(2S) to eta' pi+ pi- with a significance of 5.5sigma including systematic error is obtained, and the eta_c(2S) mass is measured to be M = [3635.1\pm3.7~(stat.)\pm2.9~(syst.)] MeV/c^{2}. The products of the two-photon decay width and branching fraction (B) of decays to eta'pi+ pi- are determined to be \Gamma_{gamma gamma}B = [65.4\pm2.6~(stat.)\pm6.9~(syst.)] eV for eta_c(1S) and [5.6^{+1.2}_{-1.1}~(stat.)\pm1.1~(syst.)] eV for eta_c(2S). A new decay mode for the eta_c(1S) to eta'f_0(2080) with f_0(2080) to pi+ pi- is observed with a statistical significance of 20sigma. The f_0(2080) mass and width are determined to be M = [2083^{+63}_{-66}~(stat.)\pm 32~(syst.)] MeV/c^{2} and \Gamma = [178^{+60}_{-178}~(stat.) \pm 55~(syst.)] MeV. The cross sections for gamma gamma to eta' pi+ pi- and eta'f_{2}(1270) are measured for the first time.Comment: 19 pages, 14 figure

    Experimental Tests of Neutron Shielding for the ATLAS Forward Region

    Get PDF
    Experimental tests devoted to the optimization of the neutron shielding for the ATLAS forward region were performed at the CERN-PS with a 4 GeV/c proton beam. Spectra of fast neutrons, slow neutrons and gamma rays escaping a block of iron (40×\times40×\times80 cm3^3) shielded with different types of neutron and gamma shields (pure polyethylene - PE, borated polyethylene - BPE, lithium filled polyethylene - LiPE, lead, iron) were measured by means of plastic scintillators, a Bonner spectrometer, a HPGe detector and a slow neutron detector. Effectiveness of different types of shielding agaisnt neutrons and γ\gamma-rays were compared. The idea of a segmented outer layer shielding (iron, BPE, iron, LiPE) for the ATLAS Forward Region was also tested

    Bounds on the width, mass difference and other properties of X(3872) --> pi+pi-J/psi decays

    Full text link
    We present results from a study of X(3872) --> pi+pi- J/psi decays produced via exclusive B--> K X(3872) decays. We determine the mass to be M_X(3872)= (3871.84\pm 0.27 (stat)\pm 0.19 (syst)) MeV, a 90% CL upper limit on the natural width of Gamma_X(3872) K+X(3872))xBf(X(3872)-->pi+pi-J/psi)=(8.61 \pm 0.82(stat) \pm 0.52 (syst)) x10^{-6}, and a ratio of branching fractions Bf(B0--> K0 X(3872))/BF(B+--> K+ X(3872))=0.50\pm 0.14(stat)\pm0.04(syst). The difference in mass between the X(3872)-->pi+pi-J/psi signals in B+ and B0 decays is Delta M_{X(3872)= (-0.69 \pm 0.97 (stat)} \pm 0.19 (syst)) MeV. A search for a charged partner of the X(3872) in the decays Bbar0-->K- X+ or B+-->K0X+, X+-->pi+pi0 J/psi resulted in upper limits on the product branching fractions for these processes that are well below expectations for the case that the X(3872) is the neutral member of an isospin triplet. In addition, we examine possible J^{PC} quantum number assignments for the X(3872) based on comparisons of angular correlations between final state particles in X(3872)-->pi+pi-J/psi decays with simulated data for J^{PC} values of 1^{++} and 2^{-+}. We examine the influence of rho-omega interference in the M(pi+pi-) spectrum. The analysis is based on a 711fb^{-1} data sample that contains 772 million BBbar meson pairs collected at the Upsilon(4S) resonance in the Belle detector at the KEKB e+e- collider.Comment: 15 pages, 10 figures and 6 tables. Submitted to Physical Review

    Evidence for a new resonance and search for the Y(4140) in γγϕJ/ψ\gamma \gamma \to \phi J/\psi

    Full text link
    The process \gamma \gamma \to \phi \jpsi is measured for \phi \jpsi masses between threshold and 5 GeV/c2{\it c}^2, using a data sample of 825 fb1^{-1} collected with the Belle detector. A narrow peak of 8.83.2+4.28.8^{+4.2}_{-3.2} events, with a significance of 3.2 standard deviations including systematic uncertainty, is observed. The mass and natural width of the structure (named X(4350)) are measured to be (4350.65.1+4.6(stat)±0.7(syst))MeV/c2(4350.6^{+4.6}_{-5.1}(\rm{stat})\pm 0.7(\rm{syst})) \hbox{MeV}/{\it c}^2 and (139+18(stat)±4(syst))MeV(13^{+18}_{-9}(\rm{stat})\pm 4(\rm{syst})) \hbox{MeV}, respectively. The product of its two-photon decay width and branching fraction to \phi\jpsi is (6.72.4+3.2(stat)±1.1(syst))eV(6.7^{+3.2}_{-2.4}(\rm{stat}) \pm 1.1(\rm{syst})) \hbox{eV} for JP=0+J^P=0^+, or (1.50.6+0.7(stat)±0.3(syst))eV(1.5^{+0.7}_{-0.6}(\rm{stat}) \pm 0.3(\rm{syst})) \hbox{eV} for JP=2+J^P=2^+. No signal for the Y(4140)\to \phi \jpsi structure reported by the CDF Collaboration in B\to K^+ \phi \jpsi decays is observed, and limits of \Gamma_{\gamma \gamma}(Y(4140)) \BR(Y(4140)\to\phi \jpsi)<41 \hbox{eV} for JP=0+J^P=0^+ or <6.0eV<6.0 \hbox{eV} for JP=2+J^P=2^+ are determined at the 90% C.L. This disfavors the scenario in which the Y(4140) is a Ds+DsD_{s}^{\ast+} {D}_{s}^{\ast-} molecule.Comment: 9 pages, 3 figures, publication in Phys. Rev. Lett. 104, 112004, 201

    Observation of an alternative χc0(2P)\chi_{c0}(2P) candidate in e+eJ/ψDDˉe^+ e^- \rightarrow J/\psi D \bar{D}

    Full text link
    We perform a full amplitude analysis of the process e+eJ/ψDDˉe^+ e^- \rightarrow J/\psi D \bar{D}, where DD refers to either D0D^0 or D+D^+. A new charmoniumlike state X(3860)X^*(3860) that decays to DDˉD \bar{D} is observed with a significance of 6.5σ6.5\sigma. Its mass is (386232+2613+403862^{+26}_{-32}{}^{+40}_{-13}) MeV/c2c^2 and width is (20167+15482+88201^{+154}_{-67}{}^{+88}_{-82}) MeV. The JPC=0++J^{PC}=0^{++} hypothesis is favored over the 2++2^{++} hypothesis at the level of 2.5σ2.5\sigma. The analysis is based on the 980 fb1\mathrm{fb}^{-1} data sample collected by the Belle detector at the asymmetric-energy e+ee^+ e^- collider KEKB.Comment: 17 pages, 11 figure

    Search for the 00^{--} Glueball in Υ(1S)\Upsilon(1S) and Υ(2S)\Upsilon(2S) decays

    Full text link
    We report the first search for the JPC=0J^{PC}=0^{--} glueball in Υ(1S)\Upsilon(1S) and Υ(2S)\Upsilon(2S) decays with data samples of (102±2)(102\pm2) million and (158±4)(158\pm4) million events, respectively, collected with the Belle detector. No significant signals are observed in any of the proposed production modes, and the 90\% credibility level upper limits on their branching fractions in Υ(1S)\Upsilon(1S) and Υ(2S)\Upsilon(2S) decays are obtained. The inclusive branching fractions of the Υ(1S)\Upsilon(1S) and Υ(2S)\Upsilon(2S) decays into final states with a χc1\chi_{c1} are measured to be \BR(\Upsilon(1S)\to \chi_{c1}+ anything) = (1.90\pm 0.43(stat.)\pm 0.14(syst.))\times 10^{-4} with an improved precision over prior measurements and \BR(\Upsilon(2S)\to \chi_{c1}+ anything) = (2.24\pm 0.44(stat.)\pm 0.20(syst.))\times 10^{-4} for the first time.Comment: 19 pages, 17 figures, Fig.10b was polished, but all the results unchanged. Paper was published in PR
    corecore