Braneworlds in bumblebee gravity

We investigate the thick braneworld scenario within the five-dimensional bumblebee gravity in the presence of a real scalar field. Since the contribution of the bumblebee field is expected to be weak, we solve the field equations in the small-parameter regime. In this situation, we develop a first-order framework to describe the brane. The results show that the function which drives the bumblebee field may engender a lumplike structure whose shape depends on the parameters. On one hand, the effect of the non-minimal coupling, controlled by $\xi$, between the bumblebee field and gravity shifts the field from the vacuum expectation value. On the other hand, the aether parameter, $\beta$, is responsible for modifying the solution inside the brane.Comment: 6 pages, double column, 2 figure

New brane-like solutions in modified four-dimensional Gauss-Bonnet gravity

We investigate solutions of a new $4D$ Gauss-Bonnet gravity. We first describe the bulk vacuum solution, then we add a massive probe scalar field, and we follow considering a self-interacting scalar field which acts as a source to support thick brane solutions in the four-dimensional Gauss-Bonnet scenario with a single extra dimension of infinite extent. We illustrate our results with some distinct brane-like configurations engendering controllable thickness.Comment: 24 pages, 6 figure

Vacuum solution within a metric-affine bumblebee gravity

We consider a metric-affine extension to the gravitational sector of the Standard-Model Extension for the Lorentz-violating coefficients $u$ and $s^{\mu\nu}$. The general results, which are applied to a specific model called metric-affine bumblebee gravity, are obtained. A Schwarzschild-like solution, incorporating effects of the Lorentz symmetry breaking through coefficient $X=\xi b^2$, is found. Furthermore, a complete study of the geodesics trajectories of particles has been accomplished in this background, emphasizing the departure from general relativity. We also compute the deflection of light within the context of the weak field approximation and verify that there exist two new contributions ascribed to the Lorentz symmetry breaking. As a phenomenological application, we compare our theoretical results with observational data in order to estimate the coefficient $X$.Comment: 22 pages, 5 figure

Gravitational traces of bumblebee gravity in metric-affine formalism

This work explores various manifestations of bumblebee gravity within the metric--affine formalism. We investigate the impact of Lorentz violation parameter, denoted as $X$, on the modification of the \textit{Hawking} temperature. Our calculations reveal that as $X$ increases, the values of the \textit{Hawking} temperature attenuate. To examine the behavior of massless scalar perturbations, specifically the \textit{quasinormal} modes, we employ the WKB method. The transmission and reflection coefficients are determined through our calculations. The outcomes indicate that a stronger Lorentz--violating parameter results in slower damping oscillations of gravitational waves. To comprehend the influence of the \textit{quasinormal} spectrum on time--dependent scattering phenomena, we present a detailed analysis of scalar perturbations in the time--domain solution. Additionally, we conduct an investigation on shadows, revealing that larger values of $X$ correspond to larger shadow radii. Lastly, we explore the concept of time delay within this framework.Comment: 29 pages and 7 figure

Nonlinear σ\sigma-models in the Eddington-inspired Born-Infeld Gravity

In this paper we consider two different nonlinear $\sigma$-models minimally coupled to Eddington-inspired Born-Infeld gravity. We show that the resultant geometries represent minimal modifications with respect to those found in GR, though with important physical consequences. In particular, wormhole structures always arise, though this does not guarantee by itself the geodesic completeness of those space-times. In one of the models, quadratic in the canonical kinetic term, we identify a subset of solutions which are regular everywhere and are geodesically complete. We discuss characteristic features of these solutions and their dependence on the relationship between mass and global charge.Comment: 19 pages, 5 figure

Perfil sanitário de rebanhos ovinos e caprinos da Microrregião do Alto Médio Gurguéia, no Sul do estado do Piauí, Brasil.

Resumo: Objetivou-se caracterizar o perfil sanitário de rebanhos caprinos e ovinos na Microrregião do Alto Médio Gurguéia, sul do estado do Piauí. Foi aplicado questionário em 53 unidades produtoras. O manejo sanitário, características das instalações e sinais clínicos das enfermidades foram descritas. Verificou-se que 92,4% dos rebanhos foram acondicionados em ?chiqueiros?. A higiene diária das instalações era realizada em 1,9% das propriedades e 13,2% não adotavam higiene sanitária alguma. A vermifugação foi a prática mais difundida (94,3%) e os principais achados clínicos foram sugestivos de doenças infecciosas e parasitárias. Conclui-se que o manejo sanitário tem sido empregado de forma inadequada, com a manifestação de sinais clínicos que podem decorrer de enfermidades peculiares a caprino e ovinocultura. Abstract: This study aimed to characterize the health profile of goats and sheep herds in the High Middle Gurguéia micro-region, the southern state of Piaui. A questionnaire was applied at 53 farms. The health management, animal facilities and clinical signs of disease were described. The results showed that 92.4% of the herds were kept in "sty". Daily hygiene of the animal facilities was carried out at 1.9% and 13.2% of farms did not adopt any health care. The worming practice was more widespread (94.3%) and the main clinical findings were suggestive of infectious and parasitic diseases. We conclude that the health management has been used inappropriately, with manifestation of clinical signs that may result from diseases peculiar to goat and sheep industr