8,957 research outputs found
Gauging Nonlinear Supersymmetry
Coset methods are used to construct the action describing the dynamics
associated with the spontaneous breaking of the local supersymmetries. The
resulting action is an invariant form of the Einstein-Hilbert action, which in
addition to the gravitational vierbein, also includes a massive gravitino
field. Invariant interactions with matter and gauge fields are also
constructed. The effective Lagrangian describing processes involving the
emission or absorption of a single light gravitino is analyzed.Comment: 20 pages, no figure
Odd-Parity Negative Modes of Einstein-Yang-Mills Black Holes and Sphalerons
An analytical proof of the existence of negative modes in the odd--parity
perturbation sector is given for all known non-abelian Einstein--Yang--Mills
black holes. The significance of the normalizability condition in the
functional stability analysis is emphasized. The role of the odd--parity
negative modes in the sphaleron interpretation of the Bartnik--McKinnon
solutions is discussed.Comment: (minor typographical errors fixed, to appear in Phys.Lett.B
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
Cylindrically symmetric solitons in Einstein-Yang-Mills theory
Recently new Einstein-Yang-Mills (EYM) soliton solutions were presented which
describe superconducting strings with Kasner asymptotic (hep-th/0610183). Here
we study the static cylindrically symmetric SU(2) EYM system in more detail.
The ansatz for the gauge field corresponds to superposition of the azimuthal
and the longitudinal components of the color magnetic field. We
derive sum rules relating data on the symmetry axis to asymptotic data and show
that generic asymptotic structure of regular solutions is Kasner. Solutions
starting with vacuum data on the axis generically are divergent. Regular
solutions correspond to some bifurcation manifold in the space of parameters
which has the low-energy limiting point corresponding to string solutions in
flat space (with the divergent total energy) and the high-curvature point where
gravity is crucial. Some analytical results are presented for the low energy
limit, and numerical bifurcation curves are constructed in the gravitating
case. Depending on the parameters, the solution looks like a straight string or
a pair of straight and circular strings. The existence of such non-linear
superposition of two strings becomes possible due to self-interaction terms in
the Yang-Mills action which suppress contribution of the circular string near
the polar axis.Comment: 21 pages, 11 figure
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
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
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