Duality Transformations and temperature inversion symmetry

We argue that the temperature inversion symmetry present in the original Casimir setup and also in other Casimir systems for which symmetrical boundary conditions are imposed is not related to the duality transformations that in the context defined in Ref. [1] are transformations relating spatial extension and temperature, and pressure and energy density. We provide an example of a Casimir system for which in principle there is no temperature inversion symmetry but nevertheless these duality transformations can be found.Comment: 5 pages, no figures, standard Late

Quantized gravitoelectromagnetism theory at finite temperature

The Gravitoelectromagnetism (GEM) theory is considered in a lagrangian formulation using the Weyl tensor components. A perturbative approach to calculate processes at zero temperature has been used. Here the GEM at finite temperature is analyzed using Thermo Field Dynamics, real time finite temperature quantum field theory. Transition amplitudes involving gravitons, fermions and photons are calculated for various processes. These amplitudes are likely of interest in astrophysics.Comment: 18 page

A note on the Lorentz force, magnetic charges and the Casimir effect

We show that in order to account for the repulsive Casimir effect in the parallel plate geometry in terms of the quantum version of the Lorentz force, virtual surface densities of magnetic charges and currents must be introduced. The quantum version of the Lorentz force expressed in terms of the correlators of the electric and magnetic fields for planar geometries yields then correctly the Casimir pressure.Comment: Simple latex file: six pages, no figure

On G\"odel-type Solution in Rastall's Gravity

Rastall's theory is a generalization of Einstein's equations in which the energy-momentum tensor is not a conserved quantity, its covariant derivative is proportional to the gradient of the Ricci scalar and this fact can be associated with quantum effects in curved space-time. In this work we will go study the Rastall's gravity in the context of the G\"odel-type universe

Lorentz violation, Gravitoelectromagnetism and Bhabha Scattering at finite temperature

Gravitoelectromagnetism (GEM) is an approach for the gravitation field that is described using the formulation and terminology similar to that of electromagnetism. The Lorentz violation is considered in the formulation of GEM that is covariant in its form. In practice such a small violation of the Lorentz symmetry may be expected in a unified theory at very high energy. In this paper a non-minimal coupling term, which exhibits Lorentz violation, is added as a new term in the covariant form. The differential cross section for Bhabha scattering in the GEM framework at finite temperature is calculated that includes Lorentz violation. The Thermo Field Dynamics (TFD) formalism is used to calculate the total differential cross section at finite temperature. The contribution due to Lorentz violation is isolated from the total cross section. It is found to be small in magnitude.Comment: 14 pages, 1 figure, accepted for publication in Mod. Phys. Lett. A. arXiv admin note: text overlap with arXiv:1801.0600

Spontaneous generation of quantum turbulence through the decay of a giant vortex in a two-dimensional superfluid

We show the generation of two-dimensional quantum turbulence through simulations of a giant vortex decay in a trapped Bose-Einstein condensate. While evaluating the incompressible kinetic energy spectra of the quantum fluid described by the Gross-Pitaevskii equation, a bilinear form in a log-log plot is verified. A characteristic scaling behavior for small momenta shows resemblance to the Kolmogorov $k^{-5/3}$ law, while for large momenta it reassures the universal behavior of the core-size $k^{-3}$ power-law. This indicates a mechanism of energy transportation consistent with an inverse cascade. The feasibility of the described physical system with the currently available experimental techniques to create giant vortices opens up a new route to explore quantum turbulence

An English translation o Bertrand's theorem

A beautiful theorem due to J. L. F. Bertrand concerning the laws of attraction that admit bounded closed orbits for arbitrarily chosen initial conditions is translated from French into English.Comment: This is English version of a beautiful theorem due to Joseph Bertrand; simple latex file, no figures, six page

Remarks on the conservation of mechanical energy in introductory mechanics

We discuss the work-kinetic energy theorem and the mechanical energy conservation theorem in the context of general physics courses. The motivation is the fact that all modern texts on introductory mechanics show the same conceptually dangerous statement that besides obliterating the concept of mechanical work, diminishing the importance of the work-kinetic energy theorem, leads to erroneous applications of the energy conservation theorem and at the same eliminates its relationship with the principle of the conservation of the mechanical momentum.Comment: Latex file, 8 pages, no figures; typos correcte

An alternative calculation of the Casimir energy for kappa-deformed electrodynamics

A simple, but effcient way of calculating regularized Casimir energies suitable for non-trivial frequency spectra is briefly described and applied to the case of a kappa-deformed scalar field theory. The results are consistent with the ones obtained by other means.Comment: Four pages, latex file. Submitted for the Proceedings of the XXIV Brazilian National Meeting on Particles and Fields held in Caxambu MG, Brazil, September 30 -- October 4, 200

On Gravitational Casimir Effect and Stefan-Boltzmann Law at Finite Temperature

Gravitons are described by the propagator in Teleparallel gravity in nearly flat space-time. Finite temperature is introduced by using Thermo Field Dynamics formalism. The Gravitational Casimir effect and Stefan-Boltzmann law are calculated as a function of temperature. Then an equation of state for gravitons is determined.Comment: 12 pages, accepted for publication in Advances in High Energy Physic