42,040 research outputs found

    A QCD sum rules calculation of the ηcDD\eta_c D^* D and ηcDsDs\eta_c D_s^* D_s form factors and strong coupling constants

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    We use the QCD sum rules for the three point correlation functions to compute the strong coupling constants of the meson vertices ηcDD\eta_c D^* D and ηcDsDs\eta_c D_s^* D_s. We consider perturbative and non-perturbative contributions, working up to dimension five on the OPE. The vertices were studied considering that each one of its three mesons are off-shell alternately. The vertex coupling constant is evaluated through the extrapolation of the three different form factors. The results obtained for the coupling constants are gηcDD=5.231.38+1.80g_{\eta_c D^* D} = 5.23^{+1.80}_{-1.38} and gηcDsDs=5.551.55+1.29g_{\eta_c D_s^* D_s}=5.55^{+1.29}_{-1.55}.Comment: 22 pages, 3 figure

    Unveiling The Sigma-Discrepancy II: Revisiting the Evolution of ULIRGs & The Origin of Quasars

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    We present the first central velocity dispersions (sigma_o) measured from the 0.85 micron Calcium II Triplet (CaT) for 8 advanced (i.e. single nuclei) local (z < 0.15) Ultraluminous Infrared Galaxies (ULIRGs). First, these measurements are used to test the prediction that the "sigma-Discrepancy," in which the CaT sigma_o is systematically larger than the sigma_o obtained from the 1.6 or 2.3 micron stellar CO band-heads, extends to ULIRG luminosities. Next, we combine the CaT data with rest-frame I-band photometry obtained from archival Hubble Space Telescope data and the Sloan Digital Sky Survey (SDSS) to derive dynamical properties for the 8 ULIRGs. These are then compared to the dynamical properties of 9,255 elliptical galaxies from the SDSS within the same redshift volume and of a relatively nearby (z < 0.4) sample of 53 QSO host galaxies. A comparison is also made between the I-band and H-band dynamical properties of the ULIRGs. We find four key results: 1) the sigma-Discrepancy extends to ULIRG luminosities; 2) at I-band ULIRGs lie on the Fundamental Plane (FP) in a region consistent with the most massive elliptical galaxies and not low-intermediate mass ellipticals as previously reported in the near-infrared; 3) the I-band M/L of ULIRGs are consistent with an old stellar population, while at H-band ULIRGs appear significantly younger and less massive; and 4) we derive an I-band Kormendy Relation from the SDSS ellipticals and demonstrate that ULIRGs and QSO host galaxies are dynamically similar.Comment: Accepted to The Astrophysical Journal. 6 Figures, 5 Tables, 4 Appendices. Version 2 changes: Corrects errors in Table 1 of Appendix C; and now formatted using ApJ emulat

    A QCD sum rules calculation of the J/ψDsDsJ/\psi D_s^* D_s strong coupling constant

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    In this work, we calculate the form factors and the coupling constant of the strange-charmed vertex J/ψDsDsJ/\psi D_s^* D_s in the framework of the QCD sum rules by studying their three-point correlation functions. All the possible off-shell cases are considered, DsD_s, DsD_s^* and J/ψJ/\psi, resulting in three different form factors. These form factors are extrapolated to the pole of their respective off-shell mesons, giving the same coupling constant for the process. Our final result for the J/ψDsDsJ/\psi D_s^* D_s coupling constant is gJ/ψDsDs=4.300.37+0.42GeV1g_{J/\psi D^*_s D_s} = 4.30^{+0.42}_{-0.37}\text{GeV}^{-1}.Comment: 17 pages, 4 figure
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