7,570 research outputs found
The decays and in the NJL model
The widths of the decays and
are calculated in the framework of the NJL
model. It is shown that these decays are defined by the and quark mass
difference. It leads to the suppression of these decays in comparison with the
main decay modes. In the process the intermediate
scalar state is taken into account. For the decays the
intermediate states with , and mesons
are used. Our estimates are compared with the results obtained in other works.Comment: 6 pages, 5 figures, 1 tabl
The processes in the extended NJL model
The process is described in the framework of
the extended NJL model. Intermediate vector mesons ,
and \rho'(1450)e^{+}e^{-}
\to \pi\pi'(1300)\rho'(1450)$ meson.Comment: 7 pages, 5 figure
Pion Polarizability in the NJL model and Possibilities of its Experimental Studies in Coulomb Nuclear Scattering
The charge pion polarizability is calculated in the Nambu-Jona-Lasinio model,
where the quark loops (in the mean field approximation) and the meson loops (in
the approximation) are taken into account. We show that quark loop
contribution dominates, because the meson loops strongly conceal each other.
The sigma-pole contribution plays the main role and
contains strong t-dependence of the effective pion polarizability at the region
. Possibilities of experimental test of this sigma-pole
effect in the reaction of Coulomb Nuclear Scattering are estimated for the
COMPASS experiment.Comment: 11 pages, 8 figure
decay in the extended NJL model
The width of the decay was calculated
in the extended NJL model. Contact interaction of boson with pion pair as
well as the contribution of the mesons in ground and first radial-exited
states are taken into account. The sum of the contact diagram and diagram with
intermediate meson in the ground state leads to the result which
coincides with the result of the vector-dominance model. Our results are in
satisfactory agreement with experimental data.Comment: 5 pages, 3 figures, 1 tabl
rho(omega)-> pi^0 pi^0 gamma, rho(omega) -> eta pi^0 gamma decays in the local quark Nambu--Jona-Lasinio model
The branching ratios and photon spectra of the rare processes rho(omega)->
pi^0 pi^0 gamma, rho(omega) -> eta pi^0 gamma are calculated in the framework
of the standard local quark Nambu--Jona-Lasinio (NJL) model. Three types of
diagrams are considered: the quark box and the pole diagrams with scalar
(sigma,a_0(980)) and vector (rho,omega) mesons. The obtained estimations for
the widths of the processes rho(omega)-> pi^0 pi^0 gamma are in satisfactory
agreement with existing experimental data. Predictions are made for the widths
of the processes rho(omega) -> eta pi^0 gamma.Comment: 6 pages, 5 figure
Cosmic Colored Black Holes
We present spherically symmetric static solutions (a particle-like solution
and a black hole solution) in the Einstein-Yang-Mills system with a
cosmological constant.Although their gravitational structures are locally
similar to those of the Bartnik-McKinnon particles or the colored black holes,
the asymptotic behavior becomes quite different because of the existence of a
cosmological horizon. We also discuss their stability by means of a catastrophe
theory as well as a linear perturbation analysis and find the number of
unstable modes.Comment: 12 pages, latex, 4 figures (available upon request
Chiral quark model with infrared cut-off for the description of meson properties in hot matter
A simple chiral quark model of the Nambu--Jona-Lasinio (NJL) type with a
quark confinement mechanism is constructed for the description of the light
meson sector of QCD at finite temperature. Unphysical quark production
thresholds in the NJL model are excluded by an infrared cut-off in the momentum
integration within quark loop diagrams. This chiral quark model satisfies the
low energy theorems. Using the vacuum masses and decay widths of \pi- and
\rho-mesons for fixing the model parameters, the properties of the \sigma-
meson are derived. Within the Matsubara formalism, the model is systematically
extended to finite temperatures where chiral symmetry restoration due to a
dropping constituent quark mass entails a vanishing of the infrared cut-off
(deconfinement) at the pion Mott temperature T_c=186 MeV. Besides of the pion
mass and weak decay constant, the masses, coupling constants and decay widths
of \sigma- and \rho-mesons in hot matter are investigated. The quark-antiquark
decay channel of the light mesons is opened for T>T_c only and becomes
particularly strong for the \rho- meson. The two-pion decay channel below T_c
has almost constant width for the \rho- meson up to T_c, but for the
\sigma-meson it closes below T_c such that a scalar meson state with vanishing
width is obtained as a precursor of the chiral/deconfinement transition.Comment: Latex file, 23 pages, 7 figure
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