A5067997705- Cosmology and Gravitation Theories
- Black Holes and Theoretical Physics
- Geophysics and Gravity Measurements
- Solar and Space Plasma Dynamics
- Noncommutative and Quantum Gravity Theories
- Dark Matter and Cosmic Phenomena
- Distributed systems and fault tolerance
- Pulsars and Gravitational Waves Research
- Data Quality and Management
- Advanced Differential Geometry Research
- Isotope Analysis in Ecology
- Galaxies: Formation, Evolution, Phenomena
Universidade Federal de Juiz de Fora
2024
Universidade Federal de Ouro Preto
2023
Universidade Federal do Espírito Santo
2017-2022
George Mason University
2017
The $f(R,T)$ gravity is a model whose action contains an arbitrary function of the Ricci scalar $R$ and trace energy-momentum tensor $T$. We consider minimally coupled $f(R,T)=\ensuremath{\chi}(R)+\ensuremath{\varphi}(T)$ shown that, for perfect fluids, analysis dynamical equations are sufficient to determine how $\ensuremath{\varphi}$ depends on $T$, independently matter fields equation state geometry space-time. Imposing conservation we obtain that dependent part must be linear in apart...
Abstract A fundamental element of scale-dependent gravity is the scale-setting procedure. We present a new covariant expression to set scale that arises when examining field equations. Considering renormalization group equations and imposing energy-momentum tensor conservation, we arrive at two models running gravitational cosmological constants. In setting, found in one model Big Bang singularity avoided, while other Hubble tension can be alleviated. At level perturbations, derived basic...
Here we apply the full Will-Nordtvedt version of Parameterized Post-Newtonian (PPN) formalism to a class General Relativity extensions that are based on nontrivial renormalization group (RG) effects at large scales. We focus models in which gravitational coupling constant $G$ is correlated with Newtonian potential. A previous PPN analysis considered specific realization RG effects, and only within Eddington-Robertson-Schiff formalism, less complete robust formulation. find stronger, more...
General relativity (GR) extensions based on renormalization group (RG) flows may lead to scale-dependent couplings with nontrivial effects at large distance scales. Here we develop further the approach in which RG scales are fully encoded an effective action and apply it cosmology. In order evaluate cosmological consequences, our main assumption is use of a scale such that (infrared) only appear perturbative (not background level). The emphasis here analytical results qualitative...
We consider an inflationary scenario in the holographic braneworld with a cosmological fluid occupying $3+1$ dimensional brane located at boundary of asymptotic ${\mathrm{ADS}}_{5}$ bulk. The contribution conformal field can be represented as modification Einstein's equations on boundary. Using these effective Einstein we calculate perturbations and derive corresponding power spectra assuming general $k$-essence type inflaton. find that affects scalar spectrum only speed sound dependence...
Near-Earth Objects (NEOs), like species extinction events, present a great threat to our home planet and human kind. The motivation of designing this architectural framework is the current lack structured architecture for process detecting, characterizing mitigating these NEO threats. Due recent establishment NASA's Planetary Defense Coordination Office (PDCO), it critical link individual facilities conducting separate research with an objective forming clearly defined collaborative system...
We explore the possibility of a consistent cosmology based on gauge-fixing independent running gravitational and cosmological constants ($G$ $\Lambda$) in framework effective quantum gravity. In particular, their this was found to satisfy $G \propto \Lambda^4$. setting, covariance theory provides energy conservation relations, which are impossible with unique scale parameter. However, by introducing second sub-dominant corresponding higher-loop corrections higher-derivative terms, one can...
We explore the possibility of a consistent cosmology based on gauge-fixing independent running gravitational and cosmological constants ($G$ $\Lambda$) in framework effective quantum gravity. In particular, their this was found to satisfy $G \propto \Lambda^4$. setting, covariance theory provides energy conservation relations, which are impossible with unique scale parameter. However, by introducing second sub-dominant corresponding higher-loop corrections higher-derivative terms, one can...
A fundamental element of scale-dependent gravity is the scale-setting procedure. We present a new covariant expression to set scale that arises when examining field equations. Considering renormalization group equations and imposing energy-momentum tensor conservation, we arrive at two models running gravitational cosmological constants. In setting, found in one model Big Bang singularity avoided, while other Hubble tension can be alleviated. At level perturbations, derived basic solutions...
The $f(R,T)$ gravity is a model whose action contains an arbitrary function of the Ricci scalar $R$ and trace energy-momentum tensor $T$. We consider separable $f (R, T ) = χ(R) + φ(T )$ shown that, for perfect fluids, dynamical equations are sufficient to determine how $φ$ depends on $T$, independently matter state equation geometry space-time. Imposing conservation we obtain that must be linear in However, $T$ dependence severely constrained using full Will-Nordtvedt version parameterized...
We consider an action for gravity that, in addition to the Einstein-Hilbert term, contains a function of Ricci scalar and Gauss-Bonnet invariant. The specific form considered is motivated by holographic cosmology. At background level field equations imply modified Friedmann same as those calculate cosmological perturbations derive corresponding power spectra assuming general $k$-inflation. find that resulting differ substantially from obtained both standard estimated spectral index...