arXiv subjects

A. Gil-Ocaranza

Publications and source records attributed to A. Gil-Ocaranza.

3 recordsLinked to original sources

arXiv2026

Exact solutions using power law scalar potential in the Saez-Ballester-K-essence like theory

We investigate a K-essence like cosmological model whose scalar-field potential is constructed from a negative power-law Sáez--Ballester potential. By means of a suitable field redefinition from $ϕ$ to $φ$, we show that the resulting field equations acquire a mathematical structure analogous to that of a previously solved Friedmann-Lemaître-Robertson-Walker (FLRW) cosmological model. This correspondence allows us to obtain exact classical solutions for both the scale factor and the scalar field within the Hamiltonian formalism. The resulting cosmological dynamics exhibits a late-time accelerated expansion, with the deceleration parameter approaching the asymptotic value $q\rightarrow -1$, characteristic of a de Sitter phase. At the quantum level, the corresponding Wheeler-DeWitt (WDW) equation is derived and exact quantum solutions are obtained. These results provide a consistent classical and quantum description of the cosmological evolution generated by this class of K-essence models. In this formalism, the scalar field remains as a cosmic background where the universe unfolds, which is glimpsed from the quantum solution perspective.

gr-qc↗

arXiv2026

Power law scalar potential in the Saez-Ballester like theory: Exact solutions in the Bianchi type I case

We investigate exact anisotropic Bianchi type I cosmological solutions in a generalized S'aez--Ballester--K-essence-like theory containing two interacting scalar fields with quintessence, phantom, and mixed (quintom) kinetic sectors. The scalar-field self-interaction is described by inverse power-law potentials, which admit analytical solutions after an appropriate transformation of the field equations. The mixed kinetic interaction imposes nontrivial constraints on the model parameters, leading to six exact cosmological branches associated with the quintessence, phantom, and quintom scenarios. The exact solutions provide explicit expressions for the effective volume and scalar fields, allowing the reconstruction of the Hubble parameter, the deceleration parameter, and the effective equation-of-state parameter. Although the six branches exhibit distinct transient behaviors, all physically admissible solutions evolve toward the same asymptotic de Sitter attractor characterized by accelerated expansion. The analytical solutions reveal how the different kinetic sectors control the cosmological evolution while preserving a common late-time behavior. These results provide a unified analytical description of anisotropic cosmological dynamics in generalized scalar-field theories and may serve as a useful framework for investigating the role of interacting scalar fields in the early and late evolution of the Universe.

gr-qc↗

arXiv2020

Scalar field unification of interacting viscous dark fluid from a geometrical scalar-tensor theory of gravity

We investigate, in the framework of a recently introduced new class of invariant geometrical scalar-tensor theory of gravity, the possibility that a viscous dark fluid can be described in a unified manner by a single scalar field. Thus we developed a model in which both the metric tensor and the scalar field have geometrical origin. The scalar field is characterized by a non-canonical kinetic term and the scalar viscosity of the dark fluid appears as soon the kinetic energy of the scalar field is no longer canonical. The scalar viscosity is considered as a function of the Hubble and the deceleration parameters. To illustrate the formalism we have considered two cases: a constant and a thermodynamic equation of state parameters. In the both cases we obtain analytic representations for the scalar field and their respective potentials. We delimit free parameters by comparing with some Planck 2018 results.

gr-qc↗