46 research outputs found
Solving integral equations in
A dispersive analysis of decays has been performed in the past
by many authors. The numerical analysis of the pertinent integral equations is
hampered by two technical difficulties: i) The angular averages of the
amplitudes need to be performed along a complicated path in the complex plane.
ii) The averaged amplitudes develop singularities along the path of integration
in the dispersive representation of the full amplitudes. It is a delicate
affair to handle these singularities properly, and independent checks of the
obtained solutions are demanding and time consuming. In the present article, we
propose a solution method that avoids these difficulties. It is based on a
simple deformation of the path of integration in the dispersive representation
(not in the angular average). Numerical solutions are then obtained rather
straightforwardly. We expect that the method also works for .Comment: 11 pages, 10 Figures. Version accepted for publication in EPJC. The
ancillary files contain an updated set of fundamental solutions. The
numerical differences to the former set are tiny, see the READMEv2 file for
detail
Truncated Schwinger-Dyson Equations and Gauge Covariance in QED3
We study the Landau-Khalatnikov-Fradkin transformations (LKFT) in momentum
space for the dynamically generated mass function in QED3. Starting from the
Landau gauge results in the rainbow approximation, we construct solutions in
other covariant gauges. We confirm that the chiral condensate is gauge
invariant as the structure of the LKFT predicts. We also check that the gauge
dependence of the constituent fermion mass is considerably reduced as compared
to the one obtained directly by solving SDE.Comment: 17 pages, 11 figures. v3. Improved and Expanded. To appear in Few
Body System
Isgur-Wise function in a QCD inspired potential model with confinement as parent in the Variationally Improved Perturbation Theory (VIPT)
We have recently reported the calculation of slope and curvature of
Isgur-Wise function based on Variationally Improved Perturbation Theory (VIPT)
in a QCD inspired potential model. In that work, Coulombic potential was taken
as the parent while the linear one as the perturbation.In this work, we choose
the linear one as the parent with Coulombic one as the perturbation and see the
consequences. Keywords: VIPT,Isgur-Wise function, charge radii and convexity
pa- rameter
The GAIA theory: from Lovelock to Margulis. From a homeostatic to a cognitive autopoietic worldview
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