Quantization and simulation of Born-Infeld non-linear electrodynamics on a lattice

Born-Infeld non-linear electrodynamics arises naturally as a field theory description of the dynamics of strings and branes. Most analyses of this theory have been limited to studying it as a classical field theory. We quantize this theory on a Euclidean 4-dimensional space-time lattice and determine its properties using Monte-Carlo simulations. The electromagnetic field around a static point charge is measured using Luscher-Weisz methods to overcome the sign problem associated with the introduction of this charge. The D field appears identical to that of Maxwell QED. However, the E field is enhanced by quantum fluctuations, while still showing the short distance screening observed in the classical theory. In addition, whereas for the classical theory, the screening increases without bound as the non-linearity increases, the quantum theory approaches a limiting conformal field theory.Comment: 24 pages, 10 figures. Latex with postscript figure

Dynamics of the Born-Infeld dyons

The approach to the dynamics of a charged particle in the Born-Infeld nonlinear electrodynamics developed in [Phys. Lett. A 240 (1998) 8] is generalized to include a Born-Infeld dyon. Both Hamiltonian and Lagrangian structures of many dyons interacting with nonlinear electromagnetism are constructed. All results are manifestly duality invariant.Comment: 11 pages, LATE

Nonperturbative calculation of Born-Infeld effects on the Schroedinger spectrum of the hydrogen atom

We present the first nonperturbative numerical calculations of the nonrelativistic hydrogen spectrum as predicted by first-quantized electrodynamics with nonlinear Maxwell-Born-Infeld field equations. We also show rigorous upper and lower bounds on the ground state. When judged against empirical data our results significantly restrict the range of viable values of the new electromagnetic constant which is introduced by the Born-Infeld theory. We assess Born's own proposal for the value of his constant.Comment: 4p., 2 figs, 1 table; submitted for publicatio

Superconductivity in Boron under pressure - why are the measured Tc_c's so low?

Using the full potential linear muffin-tin orbitals (FP-LMTO) method we examine the pressure-dependence of superconductivity in the two metallic phases of Boron: bct and fcc. Linear response calculations are carried out to examine the phonon frequencies and electron-phonon coupling for various lattice parameters, and superconducting transition temperatures are obtained from the Eliashberg equation. In both bct and fcc phases the superconducting transition temperature T$_c$ is found to decrease with increasing pressure, due to stiffening of phonons with an accompanying decrease in electron-phonon coupling. This is in contrast to a recent report, where T$_c$ is found to increase with pressure. Even more drastic is the difference between the measured T$_c$, in the range 4-11 K, and the calculated values for both bct and fcc phases, in the range 60-100 K. The calculation reveals that the transition from the fcc to bct phase, as a result of increasing volume or decreasing pressure, is caused by the softening of the X-point transverse phonons. This phonon softening also causes large electron-phonon coupling for high volumes in the fcc phase, resulting in coupling constants in excess of 2.5 and T$_c$ nearing 100 K. We discuss possible causes as to why the experiment might have revealed T$_c$'s much lower than what is suggested by the present study. The main assertion of this paper is that the possibility of high T$_c$, in excess of 50 K, in high pressure pure metallic phases of boron cannot be ruled out, thus substantiating the need for further experimental investigations of the superconducting properties of high pressure pure phases of boron.Comment: 16 pages, 8 figures, 1 Tabl

Einstein-Born-Infeld on Taub-NUT Spacetime in 2k+2 Dimensions

We wish to construct solutions of Taub-NUT spacetime in Einstein-Born-Infeld gravity in even dimensions. Since Born-Infeld theory is a nonlinear electrodynamics theory, in leads to nonlinear differential equations. However a proper analytical solution was not obtain, we try to solve it numerically (by the Runge-Kotta method) with initial conditions coinciding with those of our previous work in Einstein-Maxwell gravity. We solve equations for 4, 6 and 8 dimensions and do data fitting by the least-squares method. For N=l=b=1, the metric turns to the NUT solution only in 8 dimensions, but in 4 and 6 dimensions the spacetime does not have any Nut solution.Comment: 8 pages, 5 figure

In search of a working notion of lex sportiva

The emergence of a lex specialis regime and its interaction with the established, governing lex generalis in their overlapping spheres of application is always an intriguing legal relationship to explore. In this article, the focus will be on the development of legal principles and rules that have been/can be collectively described as lex sportiva. However, it is notable that those involved in the consideration, usage and application of this notion have not agreed as to the scope and delimitation of the concept. It is debated whether lex sportiva exists in the first place, its legal sources and its purpose. The risk is for the concept becoming redundant when not vilified as a hidden strategy to exclude non-sports-related law from the ambit of sport. Through an examination of the different propositions to the framework of the term, this article will shed light on the existence, utility and limits of the development of this conceptualisation

Downscaling heavy rainfall in the subtropics ? a simple approach for dynamical nesting

International audienceThe simulation of local scale precipitation with nested models often suffers from large errors in the boundary rows. Advection of precipitation into the model domain of the small scale model can lead to an overestimation of precipitation in the boundary grid cells of the nested model and a drying of the interior grid area. Consequently, the finer scale structure of rainfall events of the small scale model can not evolve. These errors result from three main sources: "dynamical", "scale", and "parameterization" problems. As a first step to reduce the "parameterization" boundary errors, we propose a nesting procedure where rainwater from the driving larger scale model is converted to cloud water in the smaller scale model. The nesting method is applied to a case study of heavy rainfall in semi-arid southern Morocco. The results show the elimination of erroneous excessive rainfall in the boundary rows and slightly enhanced rainfall in the interior of the nested model domain. Additionally, fine scale structures in the precipitation patterns develop. The excessive surface runoff is clearly diminished in comparison to the standard nesting procedure. The proposed approach enables scale consistent precipitation patterns resulting from model physics and grid-resolution of the smaller scale model for the complete model domain

Noise properties of two single electron transistors coupled by a nanomechanical resonator

We analyze the noise properties of two single electron transistors (SETs) coupled via a shared voltage gate consisting of a nanomechanical resonator. Working in the regime where the resonator can be treated as a classical system, we find that the SETs act on the resonator like two independent heat baths. The coupling to the resonator generates positive correlations in the currents flowing through each of the SETs as well as between the two currents. In the regime where the dynamics of the resonator is dominated by the back-action of the SETs, these positive correlations can lead to parametrically large enhancements of the low frequency current noise. These noise properties can be understood in terms of the effects on the SET currents of fluctuations in the state of a resonator in thermal equilibrium which persist for times of order the resonator damping time.Comment: Accepted for publication in Phys. Rev.

Lateral shift of the transmitted light beam through a left-handed slab

It is reported that when a light beam travels through a slab of left-handed medium in the air, the lateral shift of the transmitted beam can be negative as well as positive. The necessary condition for the lateral shift to be positive is given. The validity of the stationary-phase approach is demonstrated by numerical simulations for a Gaussian-shaped beam. A restriction to the slab's thickness is provided that is necessary for the beam to retain its profile in the traveling. It is shown that the lateral shift of the reflected beam is equal to that of the transmitted beam in the symmetric configuration.Comment: 14 pages, 4 figure

Evaluation of Born and local effective charges in unoriented materials from vibrational spectra

We present an application of the Lorentz model in which fits to vibrational spectra or a Kramers Kronig analysis are employed along with several useful formalisms to quantify microscopic charge in unoriented (powdered) materials. The conditions under which these techniques can be employed are discussed, and we analyze the vibrational response of a layered transition metal dichalcogenide and its nanoscale analog to illustrate the utility of this approach.Comment: 9 pages, 1 figur