Cosmic strings in generalized hybrid metricPalatini gravity
Abstract
We consider the possible existence of gravitationally bound stringlike objects, and approximation of local U (1 ) AbelianHiggs strings, in the framework of the generalized hybrid metricPalatini gravity theory, in which the gravitational action is represented by an arbitrary function of the Ricci and of the Palatini scalars, respectively. The theory admits an equivalent scalartensor representation in terms of two independent scalar fields. Assuming cylindrical symmetry, and the boost invariance of the metric, we obtain the gravitational field equations that describe cosmic stringlike structures in the theory. The physical and geometrical properties of the cosmic strings are determined by the two scalar fields, as well by an effective field potential, functionally dependent on both scalar fields. The field equations can be exactly solved for a vanishing, and a constant potential, respectively, with the corresponding string tension taking both negative and positive values. Furthermore, for more general classes of potentials, having an additive and a multiplicative algebraic structure in the two scalar fields, the gravitational field equations are solved numerically. For each potential we investigate the effects of the variations of the potential parameters and of the boundary conditions on the structure of the cosmic string. In this way, we obtain a large class of stable stringlike astrophysical configurations, whose basic parameters (string tension and radius) depend essentially on the effective field potential, and on the boundary conditions.
 Publication:

Physical Review D
 Pub Date:
 December 2021
 DOI:
 10.1103/PhysRevD.104.124056
 arXiv:
 arXiv:2104.12126
 Bibcode:
 2021PhRvD.104l4056D
 Keywords:

 General Relativity and Quantum Cosmology
 EPrint:
 27 pages, 16 figures, accepted for publication in PRD