511 research outputs found

    Dynamic Properties of Charmonium

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    Nonrelativistic quark models of charmonia are tested by comparison of theoretical charmonium decay constants, form factors, and γγ\gamma\gamma widths with experiment and lattice gauge computations. The importance of relativistic effects, a running coupling, and the correct implementation of bound state effects are demonstrated. We describe how an improved model and computational techniques resolve several outstanding issues in previous nonrelativistic quark models such as the use of `correction' factors in quark model form factors, artificial energy prescriptions in decay constant calculations, and ad hoc phase space modifications. We comment on the small experimental value of fψf_{\psi''} and the D-wave component of the J/ψJ/\psi. Decay constants and γγ\gamma\gamma widths for bottomonium are also presented.Comment: 22 pages, 22 ps figures (table entries corrected, text modified

    Strange-Beauty Meson Production at ppˉp\bar p Colliders

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    The production rates and transverse momentum distributions of the strange-beauty mesons BsB_s and BsB_s^* at ppˉp\bar p colliders are calculated assuming fragmentation is the dominant process. Results are given for the Tevatron in the large transverse momentum region, where fragmentation is expected to be most important.Comment: Minor changes in the discussion section. Also available at http://www.ph.utexas.edu/~cheung/paper.htm

    On the π\pi and KK as qqˉq \bar q Bound States and Approximate Nambu-Goldstone Bosons

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    We reconsider the two different facets of π\pi and KK mesons as qqˉq \bar q bound states and approximate Nambu-Goldstone bosons. We address several topics, including masses, mass splittings between π\pi and ρ\rho and between KK and KK^*, meson wavefunctions, charge radii, and the KπK-\pi wavefunction overlap.Comment: 15 pages, late

    Effect of integrated care for sick listed patients with chronic low back pain: economic evaluation alongside a randomised controlled trial

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    Objective To evaluate the cost effectiveness, cost utility, and cost-benefit of an integrated care programme compared with usual care for sick listed patients with chronic low back pain

    Ratios of BB and DD Meson Decay Constants in Relativistic Quark Model

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    We calculate the ratios of BB and DD meson decay constants by applying the variational method to the relativistic hamiltonian of the heavy meson. We adopt the Gaussian and hydrogen-type trial wave functions, and use six different potentials of the potential model. We obtain reliable results for the ratios, which are similar for different trial wave functions and different potentials. The obtained ratios show the deviation from the nonrelativistic scaling law, and they are in a pretty good agreement with the results of the Lattice calculations.Comment: 13 pages, 1 Postscript figur

    The ACRA Anatomy Study (Assessment of Disability After Coronary Procedures Using Radial Access): A Comprehensive Anatomic and Functional Assessment of the Vasculature of the Hand and Relation to Outcome After Transradial Catheterization

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    BACKGROUND: The palmar arches serve as the most important conduits for digital blood supply, and incompleteness may lead to digital ischemia when the radial artery becomes obstructed after cardiac catheterization. The rate of palmar arch incompleteness and the clinical consequences after transradial access are currently unknown.METHODS AND RESULTS: The vascular anatomy of the hand was documented by angiography in 234 patients undergoing transradial cardiac catheterization. In all patients, a preprocedural modified Allen test and Barbeau test were performed. Upper-extremity function was assessed at baseline and 2-year follow-up by the QuickDASH. Incompleteness of the superficial palmar arch (SPA) was present in 46%, the deep palmar arch was complete in all patients. Modified Allen test and Barbeau test results were associated with incompleteness of the SPA (P=0.001 and P=0.001). The modified Allen test had a 33% sensitivity and 86% specificity for SPA incompleteness with a cutoff value of >10 seconds and a 59% sensitivity and 60% specificity with a cutoff value of >5 seconds. The Barbeau test had a 7% sensitivity and 98% specificity for type D and a 21% sensitivity and 93% specificity for types C and D combined. Upper-extremity dysfunction was not associated with SPA incompleteness (P=0.77).CONCLUSIONS: Although incompleteness of the SPA is common, digital blood supply is always preserved by a complete deep palmar arch. Preprocedural patency tests have thus no added benefit to prevent ischemic complications of the hand. Finally, incompleteness of the SPA is not associated with a loss of upper-extremity function after transradial catheterization

    Di-electron and two-photon widths in charmonium

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    The vector and pseudoscalar decay constants are calculated in the framework of the Field Correlator Method. Di-electron widths: Γee(J/ψ)=5.41\Gamma_{ee}(J/\psi)=5.41 keV, Γee(ψ(3686))=2.47\Gamma_{ee}(\psi'(3686))=2.47 keV, Γee(ψ(3770))=0.248\Gamma_{ee}(\psi''(3770))=0.248 keV, in good agreement with experiment, are obtained with the same coupling, αs=0.165\alpha_s=0.165, in QCD radiative corrections. We show that the larger αs=0.191±0.004\alpha_s=0.191\pm 0.004 is needed to reach agreement with experiment for Γγγ(ηc)=7.22\Gamma_{\gamma\gamma}(\eta_c)=7.22 keV, Γγγ(χ(3P0))=3.3\Gamma_{\gamma\gamma} (\chi(^3P_0))=3.3 keV, Γγγ(χ(3P2))=0.54\Gamma_{\gamma\gamma}(\chi(^3P_2))= 0.54 keV, and also for Γ(J/ψ3g)=59.5\Gamma(J/\psi\to 3g)=59.5 keV, Γ(J/ψγ2g)=5.7\Gamma(J/\psi\to \gamma 2g)=5.7 keV. Meanwhile even larger αs=0.238\alpha_s=0.238 gives rise to good description of Γ(ψ3g)=52.7\Gamma(\psi'\to 3g)=52.7 keV, Γ(ψγ2g)=3.5\Gamma(\psi'\to \gamma 2g)= 3.5 keV, and provides correct ratio of the branching fractions: B(J/ψlighthadrons)B(ψlighthadrons)=0.24.\frac{\mathcal{B}(J/\psi\to light hadrons)}{\mathcal{B}(\psi'\to light hadrons)}=0.24.Comment: 8 pages, no figure

    The decay constants of pseudoscalar mesons in a relativistic quark model

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    The decay constants of pseudoscalar mesons are calculated in a relativistic quark model which assumes that mesons are made of a valence quark antiquark pair and of an effective vacuum like component. The results are given in terms of quark masses and of some free parameters entering the expression of the internal wave functions of the mesons. By using the pion and kaon decay constants Fπ+=130.7 MeV, FK+=159.8 MeVF_{\pi^+}=130.7~MeV,~F_{K^+}=159.8~MeV to fix the parameters of the model one gets 60 MeVFD+185 MeV, 95 MeVFDs230 MeV, 80 MeVFB+205 MeV60~MeV\leq F_{D^+}\leq 185~MeV,~95~MeV\leq F_{D_s}\leq230~MeV,~80~MeV\leq F_{B^+}\leq205~MeV for the light quark masses mu=5.1 MeV, md=9.3 MeV, ms=175 MeVm_u=5.1~MeV,~m_d=9.3~MeV,~m_s=175~MeV and the heavy quark masses in the range: 1. GeVmc1.6 GeV, 4.1 GeVmb4.5 GeV1.~GeV\leq m_c\leq1.6~GeV,~4.1~GeV\leq m_b\leq4.5~GeV. In the case of light neutral mesons one obtains with the same set of parameters Fπ0138 MeV, Fη 130 MeV,Fη 78 MeVF_{\pi^0}\approx 138~MeV,~F_\eta\approx~130~MeV,F_{\eta'} \approx~78~MeV. The values are in agreement with the experimental data and other theoretical results.Comment: 11 pages, LaTe

    Decay Constants and Semileptonic Decays of Heavy Mesons in Relativistic Quark Model

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    We investigate the BB and DD mesons in the relativistic quark model by applying the variational method with the Gaussian wave function. We calculate the Fermi momentum parameter pFp_{_F}, and obtain pF=0.500.54p_{_F} = 0.50 \sim 0.54 GeV, which is almost independent of the input parameters, αs\alpha_s, mbm_b, mcm_c and mspm_{sp}. We then calculate the ratio fBf_B/fDf_D, and obtain the result which is larger, by the factor of about 1.3, than MD/MB\sqrt{M_D / M_B} given by the naive nonrelativistic analogy. This result is in a good agreement with the recent Lattice calculations. We also calculate the ratio (MBMB)(M_{B^*}-M_{B})/(MDMD)(M_{D^*}-M_{D}). In these calculations the wave function at origin ψ(0)\psi (0) is essential. We also determine pFp_{_F} by comparing the theoretical prediction of the ACCMM model with the lepton energy spectrum of BeνXB \rightarrow e \nu X from the recent ARGUS analysis, and find that pF=0.27 ± 0.270.22p_{_F}=0.27~\pm~^{0.22}_{0.27} GeV, when we use mc=1.5m_c=1.5 GeV. However, this experimentally determined value of pFp_{_F} is strongly dependent on the value of input parameter mcm_c.Comment: 15 pages (Latex) (uses epsfig.sty, 1 figure appended as a uuencoded compressed ps-file
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