Related papers: Gravitational scalar-tensor theory
Considering the so-called Ricci-based gravity theories, a family of extensions of General Relativity whose action is given by a non-linear function of contractions and products of the (symmetric part of the) Ricci tensor of an independent…
Out of several possible extensions of general relativity, the scalar-tensor theory is the most popular for several reasons. Since the quantum description of gravity is yet to be formulated properly, the understanding of a gravitational…
The scalar normal modes of higher dimensional gravitating kink solutions are derived. By perturbing to second order the gravity and matter parts of the action in the background of a five-dimensional kink, the effective Lagrangian of the…
The scalar field theory with higher derivatives is considered in the first order formalism. The field equation of the forth order describes scalar particles possessing two mass states. The first order relativistic wave equation in the…
We present new results involving general higher-curvature gravities in three dimensions. The most general Lagrangian can be written as a function of the Ricci scalar $R$, $\mathcal{S}_2\equiv \tilde R_{a}^b \tilde R_b^a$ and…
It has recently been shown that $f(T)$ gravity has $\frac{n(n-3)}{2}+1$ physical degrees of freedom (d.o.f.) in $n$ dimensions, contrary to previous claims. The simplest physical interpretation of this fact is that the theory possesses a…
In the first order formalism of gravitational theories, the spacetime connection is considered as an independent variable to vary together with the metric. However, the metric still generates its Levi-Civita connection that turns out to…
The novel proposal to invoke the split of the Ricci scalar into bulk and boundary terms in the gravitational action, opens up a new avenue of investigation into stellar dynamics. The Lagrangian contains functional forms of the bulk term…
In any diffeomorphism invariant theory of gravity, one can define a Noether charge arising from the invariance of the Lagrangian under diffeomorphisms. We have determined the Noether charge for scalar-tensor theories of gravity, in which…
In the effective field theory approach to gravity, the Lagrangian density for general relativity is supplemented by generally covariant terms of higher order in the Riemann tensor and its derivatives. At face value, these terms will result…
We investigate the Hamiltonian structure of a class of gravitational theories whose actions are linear in the lapse function. We derive the necessary and sufficient condition for a theory in this class to have two or less local physical…
In this work, we explore the construction of the most general vector-tensor theory with an SU(2) global symmetry in the vector sector as a proposal for a modified theory of gravity. We start with a general Lagrangian containing terms…
We consider topological contributions to the action integral in a gauge theory formulation of gravity. Two topological invariants are found and are shown to arise from the scalar and pseudoscalar parts of a single integral. Neither of these…
We study new physical phenomena and constraints in generalized scalar--tensor theories of gravity with $\Phi$--dependent masses. We investigate a scenario (which can arise in string theories) with two types of $\Phi$--dependent masses which…
We point out the idea that, at small scales, gravity can be described by the standard degrees of freedom of general relativity, plus a scalar particle and a degree of freedom of a new type: the fakeon. This possibility leads to fundamental…
We construct the energy conditions for the recently proposed $f(R,L,T)$ gravity theory, for which $f$ is a generic function of the Ricci scalar $R$, matter lagrangian density $L$ and trace of the energy-momentum tensor $T$. We analyse two…
We formulate Eddington's affine gravity in a spacetime which is immersed in a larger eight dimensional space endowed with a hypercomplex structure. The dynamical equation of the first immersed Ricci-type tensor leads to gravitational field…
A fourth-order theory of gravity is considered which in terms of dynamics has the same degrees of freedom and number of constraints as those of scalar-tensor theories. In addition it admits a canonical point-like Lagrangian description. We…
We study field theory models in the context of a gravitational theory based on the requirement that the measure of integration in the action is not necessarily \sqrt{-g} but it is determined dynamically through additional degrees of…
f(R)-theories of gravity are reviewed in the framework of the matter-antimatter asymmetry in the Universe. The asymmetry is generated by the gravitational coupling of heavy (Majorana) neutrinos with the Ricci scalar curvature. In order that…