arXiv subjects
Publications and source records attributed to A. García-Parrado.
We present an \emph{ideal, conformally covariant} characterization of the family of four dimensional Lorentzian spacetimes that are conformally related to the Kerr vacuum solution.
In this paper we extend the projective symmetry of the full metric-affine Einstein-Hilbert theory to a new symmetry transformation in the space of affine connections called the amplified symmetry. We prove that the Lagrangian of the Standard Model of particle physics is invariant under this new symmetry. We also show that the gravitational Lagrangian can be modified so that the amplified symmetry extends to the gravitational sector and hence to the whole action. The new theory so constructed is shown to be dynamically equivalent to Einstein-Cartan's though genuinely metric-affine.
We define a new type of transformation for Lorentzian manifolds characterized by mapping every causal future-directed vector onto a causal future-directed vector. The set of all such transformations, which we call causal symmetries, has the structure of a submonoid. Some of their properties are investigated and we give necessary conditions for a vector field $\xiv$ to be the infinitesimal generator of a one-parameter group of causal symmetries. Some examples are discussed.