1,128 research outputs found
New torsion black hole solutions in Poincar\'e gauge theory
We derive a new exact static and spherically symmetric vacuum solution in the
framework of the Poincar\'e gauge field theory with dynamical massless torsion.
This theory is built in such a form that allows to recover General Relativity
when the first Bianchi identity of the model is fulfilled by the total
curvature. The solution shows a Reissner-Nordstr\"om type geometry with a
Coulomb-like curvature provided by the torsion field. It is also shown the
existence of a generalized Reissner-Nordstr\"om-de Sitter solution when
additional electromagnetic fields and/or a cosmological constant are coupled to
gravity.Comment: 14 pages, 0 figures, minor changes, references adde
Einstein-Yang-Mills-Lorentz black holes
Different black hole solutions of the coupled Einstein-Yang-Mills equations
have been well known for a long time. They have attracted much attention from
mathematicians and physicists since their discovery. In this work, we analyze
black holes associated with the gauge Lorentz group. In particular, we study
solutions which identify the gauge connection with the spin connection. This
ansatz allows one to find exact solutions to the complete system of equations.
By using this procedure, we show the equivalence between the Yang-Mills-Lorentz
model in curved space-time and a particular set of extended gravitational
theories.Comment: 10 pages, 0 figures, minor changes, references added. It matches the
version published in Eur. Phys. J.
Extended Reissner-Nordstr\"om solutions sourced by dynamical torsion
We find a new exact vacuum solution in the framework of the Poincar\'e Gauge
field theory with massive torsion. In this model, torsion operates as an
independent field and introduces corrections to the vacuum structure present in
General Relativity. The new static and spherically symmetric configuration
shows a Reissner-Nordstr\"om-like geometry characterized by a spin charge. It
extends the known massless torsion solution to the massive case. The
corresponding Reissner-Nordstr\"om-de Sitter solution is also compatible with a
cosmological constant and additional U(1) gauge fields.Comment: 12 pages, 0 figures, minor changes, references adde
Correspondence between Einstein-Yang-Mills-Lorentz systems and dynamical torsion models
In the framework of Einstein-Yang-Mills theories, we study the gauge Lorentz
group and establish a particular correspondence between this case and a certain
class of theories with torsion within Riemann-Cartan space-times. This relation
is specially useful in order to simplify the problem of finding exact solutions
to the Einstein-Yang-Mills equations. The applicability of the method is
divided into two approaches: one associated with the Lorentz group SO(1,n-1) of
the space-time rotations and another one with its subgroup SO(n-2). Solutions
for both cases are presented by the explicit use of this correspondence and,
interestingly, for the last one by imposing on our ansatz the same kind of
rotation and reflection symmetry properties as for a nonvanishing space-time
torsion. Although these solutions were found in previous literature by a
different approach, our method provides an alternative way to obtain them and
it may be used in future research to find other exact solutions within this
theory.Comment: 10 pages, 0 figures, minor changes, references added. It matches the
version published in Phys. Rev.
Stability in quadratic torsion theories
We revisit the definition and some of the characteristics of quadratic
theories of gravity with torsion. We start from the most general Lagrangian
density quadratic in the curvature and torsion tensors. By assuming that
General Relativity should be recovered when torsion vanishes and investigating
the behaviour of the vector and pseudovector torsion fields in the weak-gravity
regime, we present a set of necessary conditions for the stability of these
theories. Moreover, we explicitly obtain the gravitational field equations
using the Palatini variational principle with the metricity condition
implemented via a Lagrange multiplier
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