120 research outputs found
The hadronic off-shell width of meson resonances
Within the resonance chiral effective theory we study the dressed propagators
of the spin-1 fields, as arise from a Dyson-Schwinger resummation
perturbatively constructed from loop diagrams with absorptive contributions in
the s-channel. We apply the procedure to the vector pion form factor and the
elastic pion-pion scattering to obtain the off-shell width of the rho_0 meson.
We adopt a definition of the off-shell width of spin-1 meson resonances that
satisfies the requirements of analyticity, unitarity, chiral symmetry and
asymptotic behaviour ruled by QCD. To fulfil these constraints the resummation
procedure cannot consist only of self-energy diagrams. Our width definition is
shown to be independent of the formulation used to describe the spin-1 meson
resonances.Comment: 1+12 pages, 4 figures. Minor changes in text. Conclusions unchanged.
Version accepted for publication in Phys. Rev.
Main phenomenological features of the spontaneous CP violation in SU(3) x U(1) models
We analyze the phenomenological consequences of assuming spontaneous CP
violation in an SU(3) x U(1) model with three Higgs triplets and one sextuplet.
After the identification of the relevant physical scalars, we estimate the
contributions to the parameters , and coming
from the Higgs-fermion couplings.Comment: 21 pages RevTex, epsf, epsfig, 4 figure
Deconfinement and chiral restoration in nonlocal SU(3) chiral quark models
We study the features of nonlocal SU(3) chiral quark models with wave
function renormalization. Model parameters are determined from meson
phenomenology, considering different nonlocal form factor shapes. In this
context we analyze the characteristics of the deconfinement and chiral
restoration transitions at finite temperature, introducing the couplings of
fermions to the Polyakov loop. We analyze the results obtained for various
thermodynamical quantities considering different Polyakov loop potentials and
nonlocal form factors, in comparison with data obtained from lattice QCD
calculations.Comment: 25 pages, 5 figures. Discussion of results enlarged, figures
modified, references added. Version to appear in Physical Review
Generalized Ginzburg-Landau approach to inhomogeneous phases in nonlocal chiral quark models
We analyze the presence of inhomogeneous phases in the QCD phase diagram
within the framework of nonlocal chiral quark models. We concentrate in
particular in the positions of the tricritical (TCP) and Lifshitz (LP) points,
which are studied in a general context using a generalized Ginzburg-Landau
approach. We find that for all the phenomenologically acceptable model
parametrizations considered the TCP is located at a higher temperature and a
lower chemical potential in comparison with the LP. Consequently, these models
seem to favor a scenario in which the onset of the first order transition
between homogeneous phases is not covered by an inhomogeneous, energetically
favored phase.Comment: 9 pages, 1 figure. V2: Two references added, figure modified, minor
changes in the text introduced. Matches version to be published in Physics
Letters
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