7,009 research outputs found
Chern-Simons--Antoniadis-Savvidy forms and standard supergravity
In the context of the so called the Chern--Simons--Antoniadis--Savvidy
(ChSAS) forms, we use the methods for FDA decomposition in 1-forms to construct
a four-dimensional ChSAS supergravity action for the Maxwell superalgebra. On
the another hand, we use the Extended Cartan Homotopy Formula to find a method
that allows the separation of the ChSAS action into bulk and boundary
contributions and permits the splitting of the bulk Lagrangian into pieces that
reflect the particular subspace structure of the gauge algebra.Comment: 14 page
Standard General Relativity from Chern-Simons Gravity
Chern-Simons models for gravity are interesting because they provide with a
truly gauge-invariant action principle in the fiber-bundle sense. So far, their
main drawback has largely been the perceived remoteness from standard General
Relativity, based on the presence of higher powers of the curvature in the
Lagrangian (except, remarkably, for three-dimensional spacetime). Here we
report on a simple model that suggests a mechanism by which standard General
Relativity in five-dimensional spacetime may indeed emerge at a special
critical point in the space of couplings, where additional degrees of freedom
and corresponding "anomalous" Gauss-Bonnet constraints drop out from the
Chern-Simons action. To achieve this result, both the Lie algebra g and the
symmetric g-invariant tensor that define the Chern-Simons Lagrangian are
constructed by means of the Lie algebra S-expansion method with a suitable
finite abelian semigroup S. The results are generalized to arbitrary odd
dimensions, and the possible extension to the case of eleven-dimensional
supergravity is briefly discussed.Comment: 6 pages, no figures; v2: published versio
Modified newtonian dynamics and non-relativistic ChSAS gravity
In the context of the non-relativistic theories, a generalization of the
Chern--Weil-theorem allows us to show that extended Chern--Simons actions for
gravity in d=4 invariant under some specific non-relativistic groups lead to
modified Poisson equations. In some particular cases, these modified equations
have the form of the so-called MOND approach to gravity. The modifications
could be understood as due to the effects of dark matter. This result could
leads us to think that dark matter can be interpreted as a non-relativistic
limit of dark energy
Generalized Galilean Algebras and Newtonian Gravity
The non-relativistic versions of the generalized Poincar\'{e} algebras and
generalized -Lorentz algebras are obtained. This non-relativistic algebras
are called, generalized Galilean algebras type I and type II and denoted by
and
respectively. Using a generalized In\"{o}n\"{u}--Wigner contraction procedure
we find that the generalized Galilean algebras type I can be obtained from the
generalized Galilean algebras type II. The -expansion procedure allows us to
find the algebra from the Newton--Hooke
algebra with central extension. The procedure developed in Ref. \cite{newton}
allow us to show that the non-relativistic limit of the five dimensional
Einstein--Chern--Simons gravity is given by a modified version of the Poisson
equation. The modification could be compatible with the effects of Dark Matter,
which leads us to think that Dark Matter can be interpreted as a
non-relativistic limit of Dark Energy.Comment: 16 pages, no figures in 755 (2016) 433-43
Euler Chern Simons Gravity from Lovelock Born Infeld Gravity
In the context of a gauge theoretical formulation, higher dimensional gravity
invariant under the AdS group is dimensionally reduced to Euler-Chern-Simons
gravity. The dimensional reduction procedure of Grignani-Nardelli [Phys. Lett.
B 300, 38 (1993)] is generalized so as to permit reducing D-dimensional Lanczos
Lovelock gravity to d=D-1 dimensions.Comment: 6 pages, no figures, accepted for publication in Phys. Lett.
Minimal AdS-Lorentz supergravity in three-dimensions
The AdS-Lorentz superalgebra is studied and its relationship
to semigroup expansion developed. Using this mathematical tool, the invariant
tensors and Casimir operators are found. In terms of these invariants, a
three-dimensionnal Chern--Simons supergravity action with AdS-Lorentz symmetry
is constructed. The Killing spinors for a BTZ black-hole like solution of the
theory are discussed.Comment: 18 pages, matches published versio
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