42,040 research outputs found
A QCD sum rules calculation of the and form factors and strong coupling constants
We use the QCD sum rules for the three point correlation functions to compute
the strong coupling constants of the meson vertices and . 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 and .Comment: 22 pages, 3 figure
Unveiling The Sigma-Discrepancy II: Revisiting the Evolution of ULIRGs & The Origin of Quasars
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 strong coupling constant
In this work, we calculate the form factors and the coupling constant of the
strange-charmed vertex in the framework of the QCD sum rules
by studying their three-point correlation functions. All the possible off-shell
cases are considered, , and , 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 coupling constant is .Comment: 17 pages, 4 figure
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