21,230 research outputs found
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
Spectroscopy of quadrupole and octupole states in rare-earth nuclei from a Gogny force
Collective quadrupole and octupole states are described in a series of Sm and
Gd isotopes within the framework of the interacting boson model (IBM), whose
Hamiltonian parameters are deduced from mean field calculations with the Gogny
energy density functional. The link between both frameworks is the
() potential energy surface computed within the
Hartree-Fock-Bogoliubov framework in the case of the Gogny force. The
diagonalization of the IBM Hamiltonian provides excitation energies and
transition strengths of an assorted set of states including both positive and
negative parity states. The resultant spectroscopic properties are compared
with the available experimental data and also with the results of the
configuration mixing calculations with the Gogny force within the generator
coordinate method (GCM). The structure of excited states and its
connection with double octupole phonons is also addressed. The model is shown
to describe the empirical trend of the low-energy quadrupole and octupole
collective structure fairly well, and turns out to be consistent with GCM
results obtained with the Gogny force.Comment: 17 pages, 12 figures, 4 table
Structural evolution in germanium and selenium nuclei within the mapped interacting boson model based on the Gogny energy density functional
The shape transitions and shape coexistence in the Ge and Se isotopes are
studied within the interacting boson model (IBM) with the microscopic input
from the self-consistent mean-field calculation based on the Gogny-D1M energy
density functional. The mean-field energy surface as a function of the
quadrupole shape variables and , obtained from the constrained
Hartree-Fock-Bogoliubov method, is mapped onto the expectation value of the IBM
Hamiltonian with configuration mixing in the boson condensate state. The
resultant Hamiltonian is used to compute excitation energies and
electromagnetic properties of the selected nuclei Ge and
Se. Our calculation suggests that many nuclei exhibit
softness. Coexistence between prolate and oblate, as well as between spherical
and -soft, shapes is also observed. The method provides a reasonable
description of the observed systematics of the excitation energy of the
low-lying energy levels and transition strengths for nuclei below the neutron
shell closure , and provides predictions on the spectroscopy of
neutron-rich Ge and Se isotopes with , where data are scarce
or not available.Comment: 16 pages, 20 figure
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