3,425 research outputs found

    Recent developments in the modeling of heavy quarkonia

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    We examine the spectra and radiative decays of the cc-bar and bb-bar systems using a model which incorporates the complete one-loop spin-dependent perturbative QCD short distance potential, a linear confining term including (spin-dependent) relativistic corrections to order v^2/c^2, and a fully relativistic treatment of the kinetic energy. We compare the predictions of this model to experiments, including states and decays recently measured at Belle, BaBar, CLEO and CDF.Comment: 3 pages, contribution to PANIC05, Santa Fe, NM October 200

    Note on recent measurements of the \psi(1S)\to\ga \eta_C(1S) and \psi(2S)\to\ga \eta_C(1S) branching ratios

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    Recently published measurements of the branching ratios {\cal B}(\psi(1S)\to\ga \eta_C(1S)) and {\cal B}(\psi(2S)\to\ga \eta_C(1S)) by the CLEO collaboration are examined in the context of a potential model that includes both relativistic and one-loop QCD corrections to the quark-antiquark interaction. The prediction for the width \Gamma(\psi(1S)\to\ga \eta_C(1S)) is in excellent agreement with the new data but the prediction for \Gamma(\psi(2S)\to\ga \eta_C(1S)) is too small. In an effort to understand this discrepancy, we derive an upper bound on \Gamma(\psi(2S)\to\ga \eta_C(1S)) and point out its experimental value saturates this bound.Comment: Corrected typos, addeded referenc

    A "Sidewinding" Locomotion Gait for Hyper-Redundant Robots

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    This paper considers the kinematics of a novel form of hyper-redundant mobile robot locomotion which is analogous to the 'sidewinding' locomotion of desert snakes. This form of locomotion can be generated by a repetitive travel wave of mechanism bending. Using a continuous backbone curve model, we develop algorithms which enable travel in a uniform direction as well as changes in direction

    Potential model calculations and predictions for heavy quarkonium

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    We investigate the spectroscopy and decays of the charmonium and upsilon systems in a potential model consisting of a relativistic kinetic energy term, a linear confining term including its scalar and vector relativistic corrections and the complete perturbative one-loop quantum chromodynamic short distance potential. The masses and wave functions of the various states are obtained using a variational technique, which allows us to compare the results for both perturbative and nonperturbative treatments of the potential. As well as comparing the mass spectra, radiative widths and leptonic widths with the available data, we include a discussion of the errors on the parameters contained in the potential, the effect of mixing on the leptonic widths, the Lorentz nature of the confining potential and the possible ccˉc\bar{c} interpretation of recently discovered charmonium-like states.Comment: Physical Review published versio

    An evaluation of geomagnetic harmonic series for 1100 kilometers altitude

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    Geomagnetic harmonic series evaluation for 1100 kilometers altitude using satellite observation

    The scaler magnetic intensity at 1100 kilometers in middle and low latitudes

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    Satellite borne magnetometer for measuring scalar magnetic intensities in middle and low latitudes at 1100 km altitud

    The Molecular Interstellar Medium in Ultraluminous Infrared Galaxies

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    We present CO observations of a large sample of ultraluminous IR galaxies out to z = 0.3. Most of the galaxies are interacting, but not completed mergers. All but one have high CO(1-0) luminosities, log(Lco [K-km/s-pc^2]) = 9.92 +/- 0.12. The dispersion in Lco is only 30%, less than that in the FIR luminosity. The integrated CO intensity correlates Strongly with the 100 micron flux density, as expected for a black body model in which the mid and far IR radiation are optically thick. We use this model to derive sizes of the FIR and CO emitting regions and the enclosed dynamical masses. Both the IR and CO emission originate in regions a few hundred parsecs in radius. The median value of Lfir/Lco = 160 Lsun/(K-km/s-pc^2), within a factor of two of the black body limit for the observed FIR temperatures. The entire ISM is a scaled up version of a normal galactic disk with densities a factor of 100 higher, making even the intercloud medium a molecular region. Using three different techniques of H2 mass estimation, we conclude that the ratio of gas mass to Lco is about a factor of four lower than for Galactic molecular clouds, but that the gas mass is a large fraction of the dynamical mass. Our analysis of CO emission reduces the H2 mass from previous estimates of 2-5e10 Msun to 0.4-1.5e10 Msun, which is in the range found for molecular gas rich spiral galaxies. A collision involving a molecular gas rich spiral could lead to an ultraluminous galaxy powered by central starbursts triggered by the compression of infalling preexisting GMC's.Comment: 34 pages LaTeX with aasms.sty, 14 Postscript figures, submitted to ApJ Higher quality versions of Figs 2a-f and 7a-c available by anonymous FTP from ftp://sbast1.ess.sunysb.edu/solomon/
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