P. H. F. Oliveira | Searcharxiv

arXiv2024

Effects of position-dependent mass (PDM) on the bound-state solutions of a massive spin-0 particle subjected to the Yukawa potential

With the advent of Albert Einstein's theory of special relativity, Klein and Gordon made the first attempt to elevate time to the status of a coordinate in the Schrödinger equation. In this study, we graphically discuss the eigenfunctions and eigenenergies of the Klein-Gordon equation with a Yukawa-type potential (YP), within a position-dependent mass (PDM) framework. We conclude that the PDM leads to the equivalence of the positive ($E^+$) and negative ($E^-$) solution states at low energies. We observe that in the energy spectrum as a function of $η$ (YP intensity factor), the PDM can induce gap closure at the critical point where $E^+$ and $E^-$ become imaginary. In the spectrum as a function of $α$ (YP shielding factor), it can compel the energies to be zero at $α=0$, instead of being equal to $(m_0c^2)$ as in the invariant mass case.

quant-ph↗

arXiv2022

On the traversable Yukawa-Casimir wormholes

Wormholes (WH) require negative energy, and therefore an exotic matter source. Since Casimir energy is negative, it has been speculated as a good candidate to source that objects a long time ago. However only very recently a full solution for $D = 4$ has been found by Garattini, thus the Casimir energy can be a source of traversable WHs. In the manuscript published by the authors, we show that this solution is possible for all space-time of dimension $D > 3$. Recently, Garattini sought to analyze the effects of Yukawa-type terms on shape functions and obtained promising results. However, it assumes reasonably questionable premises when establishing a non-homogeneity in the Equation of State, when assuming a fixation between the constants that is only observed in the usual model and when considering the Zero Tidal Condition, not observed in Casimir's wormholes. In this work, we study the effects generated by Yukawa-type corrective factors on traversable wormhole solutions generated by Casimir energy without assuming such premises. We observe that, in addition to being possible to build traversable wormholes that satisfy all the necessary conditions, it is possible to obtain an adequate fixation of the constants in order to recover the standard case without a double limit. It was observed that, in the global and constant cases, it is possible to set a value in the shielding parameter that makes the wormhole generate a repulsive gravitational force. Finally, we observed that in the constant case there was a limitation for the shielding factor, something not observed in the original article.

gr-qc↗

arXiv2021

Traversable Casimir Wormholes in D Dimensions

Wormholes (WH) require negative energy, and therefore an exotic matter source. Since Casimir energy is negative, it has been speculated as a good candidate to source that objects a long time ago. However only very recently a full solution for D = 4 has been found by Garattini [1], thus the Casimir energy can be a source of traversable WHs. Soon later Alencar et al [2] have shown, that this is not true in D = 3. In this paper, we show that Casimir energy can be a source of the Morris-Thorne WH for all spacetime with D > 3. Finally, we add the cosmological constant and find that for D = 3 Casimir WHs are possible, however, the space must always being AdS. For D > 3, we show that the cosmological constant invert the signal with increasing throat size.

hep-th↗