We consider the most general class of teleparallel gravitational theories quadratic in the torsion tensor, in three space-time dimensions, and carry out a detailed investigation of its Hamiltonian formulation in Schwinger's time gauge. This general class is given by a family of three-parameter theories. A consistent implementation of the Legendre transform reduces the original theory to a one-parameter family of theories. By calculating the Poisson brackets, we show explicitly that the constraints of the theory constitute a first-class set. Therefore, the resulting theory is well defined with regard to time evolution. The structure of the Hamiltonian theory rules out the existence of the Newtonian

We apply the Hamiltonian formulation of teleparallel theories of gravity in 2+1 dimensions to a circularly symmetric geometry. We find a family of one-parameter black hole solutions. The BTZ solution fixes the unique free parameter of the theory. The resulting field equations coincide with the teleparallel equivalent of Einstein's three-dimensional equations. We calculate the gravitational energy of the black holes by means of the simple expression that arises in the Hamiltonian formulation and conclude that the resulting value is identical to that calculated by means of the Brown-York method.Comment: 20 pages, Latex file, no figure

We theoretically demonstrate that the transport inefficiency recently found experimentally for branched-out mesoscopic networks can also be observed in a quantum ring of finite width with an attached central horizontal branch. This is done by investigating the time evolution of an electron wave packet in such a system. Our numerical results show that the conductivity of the ring does not necessary improves if one adds an extra channel. This ensures that there exists a quantum analogue of the Braess Paradox, originating from quantum scattering and interference.

We study the gravitomagnetic effect in the context of absolute parallelism with the use of a modified geodesic equation via a free parameter b. We calculate the time difference in two atomic clocks orbiting the Earth in opposite directions and find a small correction due the coupling between the torsion of space time and the internal structure of atomic clocks measured by the free parameter.

We carry out the Hamiltonian formulation of the three- dimensional gravitational teleparallelism without imposing the time gauge condition, by rigorously performing the Legendre transform. Definition of the gravitational angular momentum arises by suitably interpreting the integral form of the constraint equation Gama^ik=0 as an angular momentum equation. The gravitational angular momentum is evaluated for the gravitational field of a rotating BTZ black hole.Comment: 17 pages, no figures, v2: some misprints corrected, Ref.s added, Eq.s revised, submitted to General Relativity and Gravitatio

The main scope of this research consists in evaluating the energymomentum (gravitational field plus matter) and gravitational angular momentum densities in the universe with global rotation, considering the Gödel-Obukhov metric. For this, we use the Hamiltonian formalism of the Teleparallel Equivalent of General Relativity (TEGR), which is justified for presenting covariant expressions for the considered quantities. We found that the total energy density calculated by the TEGR method is in agreement with the results reported by other authors in the literature using pseudotensors. The result found for the angular momentum density depends on the rotational parameter as expected. We also show explicitly the equivalence among the field equations of the TEGR and Einstein equations (RG), considering a perfect fluid and Gödel-Obukhov metric.

We theoretically investigate the role of the dielectric mismatch between materials on the energy levels and recombination energies of a core-shell nanowire. Our results demonstrate that when the dielectric constant of the core material is lower than that of the shell material, the self-image potential pushes the charge carriers towards the core-shell interface, in such a way that the ideal confinement model is no longer suitable. The effects of this interfacial confinement on the electronic properties of such wires, as well as on its response to applied magnetic fields, are discussed. PACS numbers:Great attention has been devoted to the investigation of the electronics and optical properties of core-shell nanowires (NW). In particular, the applications of these low dimensionality structure in optoelectronic and photonic devices are of interest for the electronics industry, and much effort has been dedicated to their fabrication. [1][2][3][4] In addition, studies of low dimensional systems surrounded by high dielectric constant materials continue to attract attention from many researchers [5,6] towards a continuation of the Moore's law. Recently, wire diameters of a few nanometers were experimentally achieved, [7] and carrier confinement effects in these nanowires have been reported with different levels of sophistication. [8][9][10] This work aims to investigate the dielectric mismatch effects on core-shell NW, focusing on the possibility of interfacial confinement of the carriers. As for the model structure, we consider a semiconductor cylindrical nanowire (core region) of radius R, surrounded by a different material (shell region). The interface between core and shell regions is assumed to be abrupt, i.e. the materials parameters change abruptly from the core to the shell regions. For the heterostructure materials considered in this paper, the bands mismatch creates a high potential barrier for the charge carriers in the shell, leading to a short penetration of the wave functions in this region. This rules out the role of the shell width on the energy states of the NW, since the wave functions does not reach the outer edge of the shell. The nanowire electronic structure is obtained by solving numerically a Schrödinger-like equation within the adiabatic approach and the effective mass framework.[11] The total confinement potential V i T (ρ i ) = ∆E i (ρ i ) + Σ i (ρ i ) is given by the sum of band edges discontinuities ∆E i (ρ i ) and the self-energy potential Σ i (ρ i ), where i = e, lh, hh represents the carrier types (electron, light hole and heavy hole, respectively). The latter term appears due to the dielectric mismatch, and its calculation is based on the method of the image charges. The details of this calculation can be seen in our supplementary material. [11] In a nutshell, the self-energy potential Σ i (ρ i ) inside the core region, due to a carrier located in the core region, is given by Eq. (19) of Ref. 10, whereas when the carrier is located in the shell region, the self-energy potential inside thi...

The main purpose of this paper is to explicitly verify the consistency of the energy-momentum and angular momentum tensor of the gravitational field established in the Hamiltonian structure of the Teleparallel Equivalent of General Relativity (TEGR). In order to reach these objectives, we obtained the total energy and angular momentum (matter plus gravitational field) of the closed universe of the Friedmann-Lemaître-Robertson-Walker (FLRW). The result is compared with those obtained from the pseudotensors of Einstein and Landau-Lifshitz. We also applied the field equations (TEGR) in an expanding FLRW universe. Considering the stress energymomentum tensor for a perfect fluid, we found a teleparallel equivalent of Friedmann equations of General Relativity (GR).