61 research outputs found

    A Phenomenological Analysis of Gluon Mass Effects in Inclusive Radiative Decays of the J/ψ\rm{J/\psi} and $\Upsilon

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    The shapes of the inclusive photon spectra in the processes \Jp \to \gamma X and \Up \to \gamma X have been analysed using all available experimental data. Relativistic, higher order QCD and gluon mass corrections were taken into account in the fitted functions. Only on including the gluon mass corrections, were consistent and acceptable fits obtained. Values of 0.721−0.068+0.0160.721^{+0.016}_{-0.068} GeV and 1.18−0.29+0.091.18^{+0.09}_{-0.29} GeV were found for the effective gluon masses (corresponding to Born level diagrams) for the \Jp and \Up respectively. The width ratios \Gamma(V \to {\rm hadrons})/\Gamma(V \to \gamma+ {\rm hadrons}) V=\Jp, \Up were used to determine αs(1.5GeV)\alpha_s(1.5 {\rm GeV}) and αs(4.9GeV)\alpha_s(4.9 {\rm GeV}). Values consistent with the current world average αs\alpha_s were obtained only when gluon mass correction factors, calculated using the fitted values of the effective gluon mass, were applied. A gluon mass ≃1\simeq 1 GeV, as suggested with these results, is consistent with previous analytical theoretical calculations and independent phenomenological estimates, as well as with a recent, more accurate, lattice calculation of the gluon propagator in the infra-red region.Comment: 50 pages, 11 figures, 15 table

    The Yuan-Tseh Lee Array for Microwave Background Anisotropy

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    The Yuan-Tseh Lee Array for Microwave Background Anisotropy (AMiBA) is the first interferometer dedicated to studying the cosmic microwave background (CMB) radiation at 3mm wavelength. The choice of 3mm was made to minimize the contributions from foreground synchrotron radiation and Galactic dust emission. The initial configuration of seven 0.6m telescopes mounted on a 6-m hexapod platform was dedicated in October 2006 on Mauna Loa, Hawaii. Scientific operations began with the detection of a number of clusters of galaxies via the thermal Sunyaev-Zel'dovich effect. We compare our data with Subaru weak lensing data in order to study the structure of dark matter. We also compare our data with X-ray data in order to derive the Hubble constant.Comment: accepted for publication in ApJ (13 pages, 7 figures); a version with high resolution figures available at http://www.asiaa.sinica.edu.tw/~keiichi/upfiles/AMiBA7/pho_highreso.pd

    Color-Octet J/ψJ/\psi Production in the ΄\Upsilon Decay

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    The direct production rate of ψ\psi in the ΄\Upsilon decay is shown to be dominated by the process ΄→ggg∗ \Upsilon \to ggg^* followed by g∗→ψg^* \to \psi via the color-octet mechanism proposed recently to explain the anomalous prompt charmonium production at the Tevatron. We show that this plausibly dominant process has a branching ratio compatible with the experimental data. Further experimental study in this channel is important to test the significance of the color-octet component of ccˉc\bar c pair inside the ψ\psi system.Comment: 20 pages, Standard LaTeX, 2 figures; a couple of new processes added, but conclusion unchange

    Dynamic Analysis of Rotor Flex-beams Based on Nonlinear Anisotropic Shell Models

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    An anisotropic shallow shell model is developed that accommodates transverse shearing deformations, and arbitrarily large displacements and rotations, but strains are assumed to remain small. The kinematic model developed in this paper uses three degrees of freedom to locate the direction of the normal to the shell's midplane. This model allows for an automatic compatibility of the shell model with beam models. The shell model is validated by comparing its predictions with several benchmark problems. The shell model of the flexbeam is shown to give very different results when compared to beam models. The lead-lag and torsion modes in particular are strongly affected, whereas flapping modes seem to be less affected

    Preparation of a cobalt-containing P,N-bidentate ligand ligated palladium complex: Its applications in amination and Suzuki cross-coupling reactions

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    A cobalt-containing P,N-ligand, alkyne-bridged dicobalt phosphine [(mu-PPh(2)CH(2)PPh(2))Co(2)(CO)(4) (mu,eta-Me(2)NCH(2)C = CP(Cy)(2))] (4c), was prepared from the reaction of Me(2)NCH(2)C = CPR(2) (2c) with a dppm-bridged dicobalt complex [Co(2)(CO)(6)(mu-P,P-PPh(2)CH(2)PPh(2))] (3). Further reaction of 4c with Pd(COD)Cl(2) gave a 4c-chelated palladium dichloride complex (mu-PPh(2)CH(2)PPh(2))Co(2)(CO)(4) (mu,eta-Cy(2)PC = CCH(2)NMe(2))- PdCl(2) (5c). Compound 5c was characterized by spectroscopic methods and crystal structure of 5c was determined by single-crystal X-ray diffraction techniques. It shows that 4c is an authentic cobalt-containing P,N-bidentate ligand. Amination and Suzuki reactions employing either a 4c/palladium salt system or an isolated 5c as the catalytic precursor led to satisfactory results. (c) 2009 Elsevier B.V. All rights reserved
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