arXiv subjects

I. Díaz-Saldaña

Publications and source records attributed to I. Díaz-Saldaña.

10 recordsLinked to original sources

arXiv2026

Static Black Holes and Iyer-Wald Entropy in $f(\mathcal{R},\mathcal{K})$ Gravity

We investigate static, spherically symmetric black hole solutions in a class of higher-curvature gravitational theories described by a Lagrangian that depends on the Ricci and Kretschmann scalars. The modified Einstein equations contain higher-order curvature terms. We develop a perturbative scheme to look for a black hole solution that deviates parametrically from the Schwarzschild geometry. We obtain first-order corrections to the metric by solving the resulting coupled differential equations. The corresponding Iyer--Wald entropy is then evaluated consistently to first order in the perturbative coupling. We show that the higher-curvature contribution gives rise to a power-law correction to the Bekenstein--Hawking entropy.

gr-qc↗

arXiv2026

Bosonic Spin-1 SOPHY

In this work we study the canonical quantization of a second-order pseudo-Hermitian field theory for massive spin-1 bosons transforming under the $(1,0)\oplus(0,1)$ representation of the restricted Lorentz Group and satisfying the Klein-Gordon equation.

hep-th↗

arXiv2025

Second-order pseudo-Hermitian spin-$1/2$ bosons

The canonical quantization of a field theory for spin-$1/2$ massive bosons that satisfy the Klein-Gordon equation is presented. The breakdown of the usual spin-statistics connection is due to the redefinition of the dual field, rendering the theory pseudo-Hermitian. The normal-ordered Hamiltonian is bounded from below with real eigenvalues, and the theory is consistent with microcausality and invariant under parity, charge conjugation and time reversal.

hep-th↗

arXiv2025

Strong lensing by GUP-improved black holes

We employ Bozza's method to calculate the deflection angle of light in the presence of the strong gravitational field generated by an improved Schwarzschild-like black hole whose metric, regular throughout the entire spacetime, was derived using the improved Generalized Uncertainty Principle (GUP). This framework incorporates effective quantum gravity corrections that resolve the physical singularity inside the black hole, quantified by a model parameter $\vert \tilde{Q}_{c}\vert$. In addition, the event horizon, the photon sphere, and the shadow radius receive modifications characterized by a second model parameter $\tilde{Q}_{b}$. Using observational properties of the supermassive black holes Messier~87$\ast$ and Sagittarius~A$\ast$ reported by the Event Horizon Telescope, we derive constraints on the parameter $\vert \tilde{Q}_{b}\vert$, namely $0 \leq \vert \tilde{Q}_{b}\vert \leq 0.3$. To the best of our knowledge, these are the first constraints reported in the literature for this improved GUP parameter. Since $\vert \tilde{Q}_{c}\vert$ does not play a significant role in the correction of the shadow radius, it was not possible to impose restrictions on its allowed values. However, it is important to consider a non-zero $\vert \tilde{Q}_{c}\vert$ in order to avoid a black hole singularity.

gr-qc↗

arXiv2024

Observational constraints on entropic cosmology

In this work, we derive a generalized modified Friedmann equation based on an entropy-area relation that incorporates established modifications, such as volumetric, linear, and logarithmic terms, in addition to novel entropic modifications that might yield to relevant cosmological implications at different stages of the evolution of the Universe. Some of these modifications are capable of mimicking the effects of dark energy and describing the current state of accelerated expansion of the Universe. We study particular cases of the generalized Friedmann equation and constrain the free parameters using observational datasets, including Hubble parameter measurements, baryon acoustic oscillations, and strong lensing systems. Our findings indicate that the proposed models align well with current observational data, particularly in low-redshift regimes; furthermore, these models are compatible with the value of $H_0$ obtained by the SH0ES program.

gr-qc↗

arXiv2024

Cosmic acceleration in entropic cosmology

In this paper we study the viability of an entropic cosmological model. The effects of entropic gravity are derived from a modified entropy-area relationship with a volumetric entropy term. This model describes a late time limit cosmic acceleration, whose origin is related to a volumetric term in the entropy. Moreover, we analyze the phenomenological implications of the entropic model using the Supernovae Pantheon compilation and the observational Hubble parameter data to find consistency with cosmological observations. Finally, we show the equivalence between the entropic model and a brane world cosmological model, by means of an effective geometrical construction.

gr-qc↗

arXiv2023

On the entropy of a stealth vector-tensor black hole

We apply Wald's formalism to a Lagrangian within generalised Proca gravity that admits a Schwarzschild black hole with a non-trivial vector field. The resulting entropy differs from that of the same black hole in General Relativity by a logarithmic correction modulated by the only independent charge of the vector field. We find conditions on this charge to guarantee that the entropy is a non-decreasing function of the black hole area, as is the case in GR. If this requirement is extended to black hole mergers, we find that for Planck scale black holes, a non-decreasing entropy is possible only if the area of the final black hole is several times larger than the initial total area of the merger. Finally, we discuss some implications of the vector Galileon entropy from the point of view of entropic gravity.

gr-qc↗

arXiv2021

Comments on the symmetry breaking condition in MacDowell-Mansouri action

In this work we study the symmetry breaking conditions, given by a (anti)de Sitter-valued vector field, of a full (anti)de Sitter-invariant MacDowell-Mansouri inspired action. We show that under these conditions the action breaks down to General Relativity with a cosmological constant, the four dimensional topological invariants, as well as the Holst term. We obtain the equations of motion of this action, and analyze the symmetry breaking conditions.

hep-th↗

arXiv2018

An Effective Cosmological Constant From an Entropic Formulation of Gravity

We use the ideas of entropic gravity to derive the FRW cosmological model and show that for late time evolution we have an effective cosmological constant. By using the first law of thermodynamics and the modified entropy area relationship derived from the supersymmetric Wheeler-DeWitt equation of the Schwarzschild black hole, we obtain modifications to the Friedmann equations that in the late time regime gives an effective positive cosmological constant. Therefore, this simple model can account for the dark energy component of the universe by providing an entropic origin to the cosmological constant $Λ$.

gr-qc↗

arXiv2018

On Emergent Gravity, Black Hole Entropy and Galactic Rotation Curves

In this work we derive a generalized Newtonian gravitational force and show that it can account for the anomalous galactic rotation curves. We derive the entropy-area relationship applying the Feynman-Hibbs procedure to the supersymmetric Wheeler-DeWitt equation of the Schwarzschild black hole. We obtain the modifications to the Newtonian gravitational force from the entropic formulation of gravity.

gr-qc↗