2,255 research outputs found

    A Simple Explanation for the X(3872) Mass Shift Observed for Decay to D^{*0} {D^0}bar

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    We propose a simple explanation for the increase of approximately 3 MeV/c^2 in the mass value of the X(3872) obtained from D^{*0} {D^0}bar decay relative to that obtained from decay to J/psi pi+ pi-. If the total width of the X(3872) is 2-3 MeV, the peak position in the D^{*0} {D^0}bar invariant mass distribution is sensitive to the final state orbital angular momentum because of the proximity of the X(3872) to D^{*0} {D^0}bar threshold. We show that for total width 3 MeV and one unit of orbital angular momentum, a mass shift ~3 MeV/c^2 is obtained; experimental mass resolution should slightly increase this value. A consequence is that spin-parity 2^- is favored for the X(3872).Comment: 3.5 pages, 4 eps figure

    Chiral Suppression of Scalar Glueball Decay

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    Because glueballs are SU(3)_{Flavor} singlets, they are expected to couple equally to u,d, and s quarks, so that equal coupling strengths to \pi^+\pi^- and K^+K^- are predicted. However, we show that chiral symmetry implies the scalar glueball amplitude for G_0 \to \qbq is proportional to the quark mass, so that mixing with \sbs mesons is enhanced and decays to K^+K^- are favored over \pi^+\pi^-. Together with evidence from lattice calculations and from experiment, this supports the hypothesis that f_0(1710) is the ground state scalar glueball.Comment: 9 pages; This revision reconciles posting (approximately) with published version. Posting contains figures that are omitted in the publicatio

    Renaissance of the ~1 TeV Fixed-Target Program

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    This document describes the physics potential of a new fixed-target program based on a ~1 TeV proton source. Two proton sources are potentially available in the future: the existing Tevatron at Fermilab, which can provide 800 GeV protons for fixed-target physics, and a possible upgrade to the SPS at CERN, called SPS+, which would produce 1 TeV protons on target. In this paper we use an example Tevatron fixed-target program to illustrate the high discovery potential possible in the charm and neutrino sectors. We highlight examples which are either unique to the program or difficult to accomplish at other venues.Comment: 31 pages, 11 figure

    The BES f_0(1810): a new glueball candidate

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    We analyze the f_0(1810) state recently observed by the BES collaboration via radiative J/\psi decay to a resonant \phi\omega spectrum and confront it with DM2 data and glueball theory. The DM2 group only measured \omega\omega decays and reported a pseudoscalar but no scalar resonance in this mass region. A rescattering mechanism from the open flavored KKbar decay channel is considered to explain why the resonance is only seen in the flavor asymmetric \omega\phi branch along with a discussion of positive C parity charmonia decays to strengthen the case for preferred open flavor glueball decays. We also calculate the total glueball decay width to be roughly 100 MeV, in agreement with the narrow, newly found f_0, and smaller than the expected estimate of 200-400 MeV. We conclude that this discovered scalar hadron is a solid glueball candidate and deserves further experimental investigation, especially in the K-Kbar channel. Finally we comment on other, but less likely, possible assignments for this state.Comment: 11 pages, 4 figures. Major substantive additions, including an ab-initio, QCD-based computation of the glueball inclusive decay width, evaluation of final state effects, and enhanced discussion of several alternative possibilities. Our conclusions are unchanged: the BES f_0(1810) is a promising glueball candidat

    A partial wave analysis of the centrally produced K+K- and K0K0 systems in pp interactions at 450 GeV/c and new information on the spin of the fJ(1710)

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    A partial wave analysis of the centrally produced K+K- and K0K0 channels has been performed in pp collisions using an incident beam momentum of 450 GeV/c. An unambiguous physical solution has been found in each channel. The striking feature is the observation of peaks in the S-wave corresponding to the f0(1500) and fJ(1710) with J = 0. The D-wave shows evidence for the f2(1270)/a2(1320), the f2(1525) and the f2(2150) but there is no evidence for a statistically significant contribution in the D-wave in the 1.7 GeV mass region.Comment: 15 pages, Latex, 5 Figure

    Study of the P-wave charmonium state \chi_{cJ} in \psi(2S) decays

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    The processes ψ(2S)γπ+π\psi(2S)\to \gamma \pi^+ \pi^-, γK+K\gamma K^+ K^- and γppˉ\gamma p \bar{p} have been studied using a sample of 3.7×1063.7 \times 10^6 produced ψ(2S)\psi(2S) decays. We determine the total width of the χc0\chi_{c0} to be Γχc0tot=14.3±2.0±3.0\Gamma^{tot}_{\chi_{c0}} = 14.3\pm 2.0\pm 3.0 MeV. We present the first measurement of the branching fraction B(χc0ppˉ)=(16.3±4.4±5.4)×105B(\chi_{c0} \to p \bar{p}) = (16.3 \pm 4.4 \pm 5.4)\times 10^{-5}, where the first error is statistical and the second one systematic. Branching fractions of χc0,2π+π\chi_{c0,2} \to \pi^+ \pi^- and K+KK^+ K^- are also reported.Comment: 10 pages, revtex, 3 figures, 2 table

    Measurement of the Inclusive Charm Cross Section at 4.03 GeV and 4.14 GeV

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    The cross section for charmed meson production at s=4.03\sqrt{s} = 4.03 and 4.14 GeV has been measured with the Beijing Spectrometer. The measurement was made using 22.3 pb1pb^{-1} of e+ee^+e^- data collected at 4.03 GeV and 1.5 pb1pb^{-1} of e+ee^+e^- data collected at 4.14 GeV. Inclusive observed cross sections for the production of charged and neutral D mesons and momentum spectra are presented. Observed cross sections were radiatively corrected to obtain tree level cross sections. Measurements of the total hadronic cross section are obtained from the charmed meson cross section and an extrapolation of results from below the charm threshold.Comment: 11 pages, 13 figures. The top level tex file is paper.tex. It builds the paper from other tex files in this .tar and the .eps file

    Measurement of ψ(2S)\psi(2S) decays to baryon pairs

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    A sample of 3.95M ψ(2S)\psi(2S) decays registered in the BES detector are used to study final states containing pairs of octet and decuplet baryons. We report branching fractions for ψ(2S)ppˉ\psi(2S)\to p\bar{p}, ΛΛˉ\Lambda\bar{\Lambda}, Σ0Σˉ0\Sigma^0\bar{\Sigma}{}^0, ΞΞˉ+\Xi^-\bar{\Xi}{}^+, Δ++Δˉ\Delta^{++}\bar{\Delta}{}^{--}, Σ+(1385)Σˉ(1385)\Sigma^+(1385)\bar{\Sigma}{}^-(1385), Ξ0(1530)Ξˉ0(1530)\Xi^0(1530)\bar{\Xi}{}^0(1530), and ΩΩˉ+\Omega^-\bar{\Omega}{}^+. These results are compared to expectations based on the SU(3)-flavor symmetry, factorization, and perturbative QCD.Comment: 22 pages, 21 figures, 4 table

    Measurement of the Total Cross Section for Hadronic Production by e+e- Annihilation at Energies between 2.6-5 Gev

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    Using the upgraded Beijing Spectrometer (BESII), we have measured the total cross section for e+ee^+e^- annihilation into hadronic final states at center-of-mass energies of 2.6, 3.2, 3.4, 3.55, 4.6 and 5.0 GeV. Values of RR, σ(e+ehadrons)/σ(e+eμ+μ)\sigma(e^+e^-\to {hadrons})/\sigma(e^+e^-\to\mu^+\mu^-), are determined.Comment: Submitted to Phys. Rev. Let
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