26 citations · 76 across the 18 of their papers we have counts for
19 papers
Alternative Hamiltonian and Lagrangian Approaches for Constrained Systems
M. A. de Andrade, C. Neves, E. V. Corrêa Silva
While standard Hamiltonian and Lagrangian methods are powerful for unconstrained classical systems, they are not directly suited to constrained ones, despite the existence of well-…
Quantum Tunneling and the Emergence of Classical Spacetime in Einstein-Æther Quantum Cosmology
Germano A. Monerat, Alessandro O. Castro Junior, Eduardo V. Corrêa Silva +1
We investigate a quantum cosmological model within the framework of Einstein-Æther gravity. The model consists of a positively curved FLRW Universe whose matter content is describe…
Barcelos-Wotzasek symplectic algorithm for constrained systems revisited
M. A. de Andrade, C. Neves, E. V. Corrêa Silva
A minor change in the Barcelos-Wotzasek (BW) symplectic algorithm for constrained systems is proposed. The change addresses some criticism that formalism has received, placing it o…
Primordial Universe with radiation and Bose-Einstein condensate
F. G. Alvarenga, L. G. Ferreira Filho, R. Fracalossi +5
In this work we derive a scenario {in which} the early universe consists of {radiation fluid} and Bose-Einstein condensate. The possibility of gravitational self-interaction due to…
Comparison of the ferromagnetic Blume-Emery-Griffiths model and the AF spin-1 longitudinal Ising model at low temperature
M. T. Thomaz, E. V. Corrêa Silva
We derive the exact Helmholtz free energy (HFE) of the standard and staggered one-dimensional Blume-Emery-Griffiths (BEG) model in the presence of an external longitudinal magnetic…
Noncommutativity in the early Universe
G. Oliveira-Neto, M. Silva de Oliveira, G. A. Monerat +1
In the present work, we study the noncommutative version of a quantum cosmology model. The model has a Friedmann-Robertson-Walker geometry, the matter content is a radiative perfec…
Quantum noncomutativity in quantum cosmology
G. Oliveira-Neto, G. A. Monerat, E. V. Corrêa Silva +2
In the present work, we study the noncommutative version of a quantum cosmology model. The model has a Friedmann-Robertson-Walker geometry, the matter content is a radiative perfec…
Can noncommutativity affect the whole history of the Universe?
G. A. Monerat, E. V. Corrêa Silva, C. Neves +3
We study a classical, noncommutative (NC), Friedmann-Robertson-Walker cosmological model. The spatial sections may have positive, negative or zero constant curvatures. The matter c…
An Early Universe Model with Stiff Matter and a Cosmological Constant
G. Oliveira-Neto, G. A. Monerat, E. V. Corrêa Silva +2
In the present work, we study the quantum cosmology description of a Friedmann-Robertson-Walker model in the presence of a stiff matter perfect fluid and a negative cosmological co…
Canonical transformation for stiff matter models in quantum cosmology
C. Neves, G. A. Monerat, G. Oliveira-Neto +2
In the present work we consider Friedmann-Robertson-Walker models in the presence of a stiff matter perfect fluid and a cosmological constant. We write the superhamiltonian of thes…
The Planck era with a negative cosmological constant and cosmic strings
G. A. Monerat, L. G. Ferreira Filho, G. Oliveira-Neto +2
In the present letter, we consider the DeBroglie-Bohm interpretation of quantum Friedmann-Robertson-Walker models in the presence of a negative cosmological constant and cosmic str…
Probing singularities in quantum cosmology with curvature scalars
G. Oliveira Neto, E. V. Correa Silva, N. A. Lemos +1
We provide further evidence that the canonical quantization of cosmological models eliminates the classical Big Bang singularity, using the {\it DeBroglie-Bohm} interpretation of q…
Tunneling probability for the birth of an asymptotically DeSitter universe
J. Acacio de Barros, E. V. Corrêa Silva, G. A. Monerat +3
In the present work, we quantize a closed Friedmann-Robertson-Walker model in the presence of a positive cosmological constant and radiation. It gives rise to a Wheeler-DeWitt equa…
Thermodynamics of the quantum spin-S XXZ chain
Onofre Rojas, S. M. de Souza, E. V. Correa Silva +1
The thermodynamics of the spin- anisotropic quantum chain with arbitrary value of and unitary norm, in the high-temperature regime, is reported. The single-ion anisotr…
Numerical Calculations Using Maple: Why & How?
E. V. Correa Silva, L. G. S. Duarte, L. A. C. P. da Mota +1
The possibility of interaction between Maple and numeric compiled languages in performing extensive numeric calculations is exemplified by the Ndynamics package, a tool for studyin…
Grassmann Algebra and Fermions at Finite Temperature
I. C. Charret, E. V. Corrêa Silva, S. M. de Souza +2
For any d-dimensional self-interacting fermionic model, all coefficients in the high-temperature expansion of its grand canonical partition function can be put in terms of multivar…
On the Electromagnetic Response of Charged Bosons Coupled to a Chern-Simons Gauge Field: A Path Integral Approach
D. G. Barci, E. V. Correa Silva, J. F. Medeiros Neto
We analyze the electromagnetic response of a system of charged bosons coupled to a Chern-Simons gauge field. Path integral techniques are used to obtain an effective action for the…
Analytical Results for the Grand-Canonical Partition Function for Unidimensional Hubbard Model up to Order
I. C. Charret, E. V. Correa Silva, S. M. de Souza +1
We calculate the exact analytical coefficients of the expansion of the grand-canonical partition function of the unidimensional Hubbard model up to order , using an altern…
Grand Canonical Partition Function for Unidimensional Systems: Application to Hubbard Model up to Order beta^3
I. C. Charret, S. M. de Souza, M. T. Thomaz +1
We exploit the grassmannian nature of the variables involved in the path integral expression of the grand canonical partition function for self--interacting fermionic models to sho…