Romualdo Tresguerres

HYPERFLUID - A MODEL OF CLASSICAL MATTER WITH HYPERMOMENTUM

Abstract A variational theory of a continuous medium is developed the elements of which carry momentum and hypermomentum ( hyperfluid ). It is shown that the structure of the sources in metric-affine gravity is predetermined by the conservation identifies and, when using the Weyssenhoff ansatz , these explicitly yield the hyperfluid currents.

An Exact solution of the metric affine gauge theory with dilation, shear, and spin charges

Abstract The spacetime of the metric-affine gauge theory of gravity (MAG) encompasses nonmetricity Qαβ and torsion Tα as post-Riemannian structures. The sources of MAG are the conserved currents of energy-momentum and dilation ⊕ shear ⊕ spin. We present an exact static spherically symmetric vacuum solution of the theory describing the exterior of a lump of matter carrying mass and dilation ⊕ shear ⊕ spin charges.

Nonlinear gauge realization of spacetime symmetries including translations

We present a general scheme for the nonlinear gauge realizations of spacetime groups on coset spaces of the groups considered. In order to show the relevance of the method for the rigorous treatment of the translations in gravitational gauge theories, we apply it in particular to the affine group. This is an illustration of the family of spacetime symmetries having the form of a semidirect productH ⊗ T, whereH is the stability subgroup andT are the translations. The translational component of the connection behaves like a true tensor underH when coset realizations are involved.

An axially symmetric solution of metric-affine gravity

We present an exact stationary axially symmetric vacuum solution of metric-affine gravity (MAG) which generalizes the recently reported spherically symmetric solution; besides the metric, it carries nonmetricity and torsion as post-Riemannian geometrical structures. The parameters of the solution are interpreted as mass and angular momentum and as dilation, shear and spin charges.

Exact static vacuum solution of four-dimensional metric affine gravity with nontrivial torsion

Abstract We present an exact spherically symmetric vacuum solution for a metric-affine quadratic Lagrangian. The metric part of the solution is of Reissner-Nordstrom type. The connection part includes nonmetricity depending on a dilatation charge and a shear charge. Furthermore, a nontrivial torsion depending on a certain torsion mass and with intrinsic contributions is present.

Ordinary matter in non-linear affine gauge theories of gravitation

We present a general framework to include ordinary fermionic matter in the metric--affine gauge theories of gravity. It is based on a non-linear gauge realization of the affine group, with the Lorentz group as the classification subgroup of the matter and gravitational fields.We present a general framework to include ordinary fermionic matter in the metric--affine gauge theories of gravity. It is based on a nonlinear gauge realization of the affine group, with the Lorentz group as the classification subgroup of the matter and gravitational fields.

Gravitational contribution to fermion masses

Abstract.In the context of a non-linear gauge theory of the Poincaré group, we show that covariant derivatives of Dirac fields include a coupling to the translational connections, manifesting itself in the matter action as a universal background mass contribution to fermions.PACS. 04.50. + h, 11.15.-q

Exact vacuum solutions of 4-dimensional metric-affine gauge theories of gravitation

We presenttwo exact spherically symmetric vacuum solutions of gauge theories of gravity on a spacetime with non metric-compatible connection. One of them is defined on a Weyl-Cartan spacetime and the other on a general metric-affine space. We consider Lagrangians which include terms quadratic in the irreducible parts of the curvature, the torsion, and the nonmetricity. The metric part of both solutions is of the Reissner-Nordström type and includes a contribution of an effectivedilatation charge. A nontrivial Weyl 1-form is also common to both solutions. It resembles a Coulomb potential originating from thedilatation charge. The torsion is closely related to the nonmetricity.

An exact solution of (2 + 1)-dimensional topological gravity in metric-affine spacetime

Abstract We present a solution of a generalized topological theory of gravity defined in a three-dimensional metric-affine spacetime. The solution includes nonmetricity and torsion. Both are functions of the conformal factor present in the triads ϑ α .

Husain-Kuchař model: Time variables and nondegenerate metrics

We study the Husain-Kuchayr model by introducing a new action principle similar to the self-dual action used in the Ashtekar variables approach to Quantum Gravity. This new action has several interesting features; among them, the presence of a scalar time variable that allows the definition of geometric observables without adding new degrees of freedom, the appearance of a natural non-degenerate four-metric and the possibility of coupling ordinary matter.