17,567 research outputs found
N=1 Supergravity and Maxwell superalgebras
We present the construction of the supergravity action from the minimal
Maxwell superalgebra , which can be derived from the
superalgebra by applying the abelian
semigroup expansion procedure. We show that , pure supergravity can
be obtained alternatively as the MacDowell-Mansouri like action built from the
curvatures of the Maxwell superalgebra . We extend this
result to all minimal Maxwell superalgebras type . The
invariance under supersymmetry transformations is also analized.Comment: 22 pages, published versio
Maxwell Superalgebras and Abelian Semigroup Expansion
The Abelian semigroup expansion is a powerful and simple method to derive new
Lie algebras from a given one. Recently it was shown that the -expansion of
leads us to the Maxwell algebra
. In this paper we extend this result to superalgebras, by proving
that different choices of abelian semigroups lead to interesting
Maxwell Superalgebras. In particular, the minimal Maxwell superalgebra
and the -extended Maxwell superalgebra recently found by the Maurer Cartan expansion procedure, are
derived alternatively as an -expansion of . Moreover we show that new minimal Maxwell superalgebras type
and their -extended generalization can be obtained
using the -expansion procedure.Comment: 31 pages, some clarifications in the abstract,introduction and
conclusion, typos corrected, a reference and acknowledgements added, accepted
for publication in Nuclear Physics
Lovelock gravities from Born-Infeld gravity theory
We present a Born-Infeld gravity theory based on generalizations of Maxwell
symmetries denoted as . We analyze different configuration
limits allowing to recover diverse Lovelock gravity actions in six dimensions.
Further, the generalization to higher even dimensions is also considered.Comment: v3, 15 pages, two references added, published versio
Chern-Simons and Born-Infeld gravity theories and Maxwell algebras type
Recently was shown that standard odd and even-dimensional General Relativity
can be obtained from a -dimensional Chern-Simons Lagrangian invariant
under the algebra and from a -dimensional Born-Infeld
Lagrangian invariant under a subalgebra respectively. Very
Recently, it was shown that the generalized In\"on\"u-Wigner contraction of the
generalized AdS-Maxwell algebras provides Maxwell algebras types
which correspond to the so called Lie algebras. In this article we
report on a simple model that suggests a mechanism by which standard
odd-dimensional General Relativity may emerge as a weak coupling constant limit
of a -dimensional Chern-Simons Lagrangian invariant under the Maxwell
algebra type , if and only if . Similarly, we show
that standard even-dimensional General Relativity emerges as a weak coupling
constant limit of a -dimensional Born-Infeld type Lagrangian invariant
under a subalgebra of the Maxwell algebra type, if and
only if . It is shown that when this is not possible for a
-dimensional Chern-Simons Lagrangian invariant under the
and for a -dimensional Born-Infeld type Lagrangian
invariant under algebra.Comment: 30 pages, accepted for publication in Eur.Phys.J.C. arXiv admin note:
text overlap with arXiv:1309.006
Generalized Poincare algebras and Lovelock-Cartan gravity theory
We show that the Lagrangian for Lovelock-Cartan gravity theory can be
re-formulated as an action which leads to General Relativity in a certain
limit. In odd dimensions the Lagrangian leads to a Chern-Simons theory
invariant under the generalized Poincar\'{e} algebra
while in even dimensions the Lagrangian leads to a Born-Infeld theory invariant
under a subalgebra of the algebra. It is also shown that
torsion may occur explicitly in the Lagrangian leading to new torsional
Lagrangians, which are related to the Chern-Pontryagin character for the
group.Comment: v2: 18 pages, minor modification in the title, some clarifications in
the abstract, introduction and section 2, section 4 has been rewritten, typos
corrected, references added. Accepted for publication in Physic letters
Few-body decay and recombination in nuclear astrophysics
Three-body continuum problems are investigated for light nuclei of
astrophysical relevance. We focus on three-body decays of resonances or
recombination via resonances or the continuum background. The concepts of
widths, decay mechanisms and dynamic evolution are discussed. We also discuss
results for the triple decay in connection with resonances and
density and temperature dependence rates of recombination into light nuclei
from -particles and neutrons.Comment: 9 pages, 8 figures. Proceedings of the 21st European Few Body
Conference held in Salamanca (Spain) in August-September 201
Positivity in the presence of initial system-environment correlation
The constraints imposed by the initial system-environment correlation can
lead to nonpositive Dynamical maps. We find the conditions for positivity and
complete positivity of such dynamical maps by using the concept of an
assignment map. Any initial system-environment correlations make the assignment
map nonpositive, while the positivity of the dynamical map depends on the
interplay between the assignment map and the system-environment coupling. We
show how this interplay can reveal or hide the nonpositivity of the assignment
map. We discuss the role of this interplay in Markovian models.Comment: close to the published version. 5 pages, 1 figur
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