5,771 research outputs found
A MASTER FORMULA FOR CHIRAL SYMMETRY BREAKING
We derive a master formula for chiral breaking, based on
the Veltman-Bell equations and the Peierls-Dyson relation. Our approach does
not rely on the use of the soft pion limit or an expansion around the chiral
limit, and yields exact results for on-shell pions. Threshold theorems for , , ,
, and are recovered, and corrections to them are given. The
reactions , ,
and are also
discussed. A general formula for scattering and a new one loop
effective action are obtained. The new effective action reproduces the KSFR
relation, and yields specific estimates for the pion polarisabilities. A
detailed comparison with baryon-free chiral perturbation theory to one loop is
made. An extension of our effective action to two loops is outlined.Comment: 119 pages + 7 Figures available from (I.Zahed
Meson vacuum phenomenology in a three-flavor linear sigma model with (axial-)vector mesons
We study scalar, pseudoscalar, vector, and axial-vector mesons with
non-strange and strange quantum numbers in the framework of a linear sigma
model with global chiral symmetry. We perform a
global fit of meson masses, decay widths, as well as decay amplitudes. The
quality of the fit is, for a hadronic model that does not consider
isospin-breaking effects, surprisingly good. We also investigate the question
whether the scalar states lie below or above 1 GeV and find the
scalar states above 1 GeV to be preferred as states. Additionally,
we also describe the axial-vector resonances as states.Comment: 29 pages, 4 figures, 3 tables. v2 is the updated version after
referee remarks (dilaton field discussed, a new figure added
Further Analysis on \sigma-particle Properties
In a previous work, we have reanalyzed the I=0 S-wave \pi\pi-scattering
phase-shift through a new method of Interfering Breit-Wigner amplitudes, and
have shown the existence of a light scalar, \sigma particle, accompanied by a
negative "repulsive core"-type background phase-shift, whose origin may have
some correspondence to a ``compensating'' \pi\pi contact interaction. In this
work we make further analysis on the phase shift under KKbar threshold from the
same standpoint, to determine precise values of \sigma mass and width, so far
as present experimental data are concerned.Comment: Updated with recent progres
On the semiclassical mass of -kinks
One-loop mass shifts to the classical masses of stable kinks arising in a
massive non-linear -sigma model are computed. Ultraviolet
divergences are controlled using the heat kernel/zeta function regularization
method. A comparison between the results achieved from exact and
high-temperature asymptotic heat traces is analyzed in depth.Comment: RevTex file, 15 pages, 2 figures. Version to appear in Journal of
Physics
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