10,095 research outputs found
On the instabilities of the static, spherically symmetric SU(2) Einstein-Yang-Mills-Dilaton solitons and black holes
We prove that the number of odd parity instabilities of the n-th SU(2)
Einstein-Yang-Mills-Dilaton soliton and black hole equals n.Comment: Added reference
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
Instability Proof for Einstein-Yang-Mills Solitons and Black Holes with Arbitrary Gauge Groups
We prove that static, spherically symmetric, asymptotically flat soliton and
black hole solutions of the Einstein-Yang-Mills equations are unstable for
arbitrary gauge groups, at least for the ``generic" case. This conclusion is
derived without explicit knowledge of the possible equilibrium solutions.Comment: 26 pages, LATEX, no 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
Einstein-Yang-Mills-Chern-Simons solutions in D=2n+1 dimensions
We investigate finite energy solutions of the
Einstein--Yang-Mills--Chern-Simons system in odd spacetime dimensions, D=2n+1,
with n>1. Our configurations are static and spherically symmetric, approaching
at infinity a Minkowski spacetime background. In contrast with the Abelian
case, the contribution of the Chern-Simons term is nontrivial already in the
static, spherically symmetric limit. Both globally regular, particle-like
solutions and black holes are constructed numerically for several values of D.
These solutions carry a nonzero electric charge and have finite mass. For
globally regular solutions, the value of the electric charge is fixed by the
Chern-Simons coupling constant. The black holes can be thought as non-linear
superpositions of Reissner-Nordstrom and non-Abelian configurations. A
systematic discussion of the solutions is given for D=5, in which case the
Reissner-Nordstrom black hole becomes unstable and develops non-Abelian hair.
We show that some of these non-Abelian configurations are stable under linear,
spherically symmetric perturbations. A detailed discussion of an exact D=5
solution describing extremal black holes and solitons is also provided.Comment: 34 pages, 14 figures; v2: misprints corrected and references adde
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
On Yang-Mills instantons in a spherically symmetric background
We present arguments for the existence of self-dual Yang-Mills instantons for
several spherically symmetric backgrounds with Euclidean signature. The
time-independent Yang-Mills field has finite action and a vanishing energy
momentum tensor and does not disturb the geometry. We conjecture the existence
of similar solutions for any nonextremal SO(3)-spherically symmetric
background.Comment: 6 pages, 3 figures; v2: references adde
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
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