Narrow Results

We study electric-magnetic duality rotations for noncommutative electromagnetism (NCEM). We express NCEM as a nonlinear commutative U(1) gauge theory and show that it is self-dual when the noncommutativity parameter θ is light-like (e.g. θ⁰ⁱ=θ¹ⁱ). This implies, in the slowly varying field approximation, self-duality of NCEM to all orders in θ.

A non-Abelian Born–Infeld theory is presented. Its construction does not require the square-root structure that characterizes the Dirac–Born–Infeld (DBI) action. The procedure is based on an Abelian theory proposed by Schrödinger that, as he showed, is equivalent to Born–Infeld theory. Various non-Abelian generalizations are possible. We focus our attention on one of them. For it, it is shown that instantons solutions exist. Our formalism could be of interest in connection with string theory and possible extensions of well-known physical results in the usual Born–Infeld Abelian case.

We construct solutions of a model which includes the Gauss–Bonnet and Born–Infeld terms for various horizon topologies (k = 0, ±1), and then the mass, temperature, entropy, and heat capacity of black holes are computed. For the sake of simplicity, we perform the stability analysis of five-dimensional topological black holes in AdS space.

We present black hole solutions in (2+1)-dimensional Einstein’s theory of gravity coupled with Born–Infeld (BI) nonlinear electrodynamic and a massless self-interacting scalar field. The model has five free parameters: mass $M$, cosmological constant $\ell$, electric $q$ and scalar $r_0$ charges and BI parameter $\beta$. To attain exact solution for such a highly nonlinear system we adjust, i.e. finely tune, the parameters of the theory with the integration constants. In the limit $\beta \to 0$, we recover the results of Einstein–Maxwell–Scalar theory, obtained before. The self-interacting potential admits finite minima apt for the vacuum contribution. Hawking temperature of the model is investigated versus properly tuned parameters. By employing this tuned-solution as basis, we obtain also a dynamic solution which in the proper limit admits the known solution in Einstein gravity coupled with self-interacting scalar field. Finally, we establish the equations of a general scalar–tensor field coupled to nonlinear electrodynamics (NED) field in 2+1 dimensions without searching for exact solutions.

Radiative extensions of BTZ metric in 2 + 1 dimensions are found which are sourced by nonlinear Maxwell fields and a null current. This may be considered as generalization of the problem formulated long go by Vaidya and Bonnor. The mass and charge are functions of retarded/advanced null coordinate apt for decay/inflation. The new solutions are constructed through a Theorem that works remarkably well for any nonlinear electrodynamic model. Hawking temperature is analyzed for the case of the Born–Infeld electrodynamics.

Starting with a simple two-scalar field system coupled to a modified measure that is independent of the metric, we, first, find a Born–Infeld dynamics sector of the theory for a scalar field and second, show that the initial scale invariance of the action is dynamically broken and leads to a scale charge nonconservation, although there is still a conserved dilatation current.

Following the work of David Fairlie and his collaborators, we discuss the geometry of the equations of motion for the companion Lagrangian. This arises while we attempt to construct the field theoretic Lagrangians for strings and branes. These equations are related to generalized Bateman equations. Interestingly, an inhomogeneous form of these equations are related to what Dubrovin and Novikov called equations of the hydrodynamic type. We translate this set of equations into (Nambu)–Poisson equations and formulate the Lax representation of these systems. We deform all this set of equations by the Moyal product. We also present the Lax pair of the Moyal deformed systems for some special cases.

We rewrite the Born–Infeld Lagrangian, which is originally given by the determinant of a 4×4 matrix composed of the metric tensor g and the field strength tensor F, using the determinant of a (4·2ⁿ)×(4·2ⁿ) matrix H_4·2ⁿ. If the elements of H_4·2ⁿ are given by the linear combination of g and F, it is found, based on the representation matrix for the multiplication operator of the Cayley–Dickson algebras, that H_4·2ⁿ is distinguished by a single parameter, where distinguished matrices are not similar matrices. We also give a reasonable condition to fix the parameter.

We propose a generalization of gravitational interactions where the action contains, instead of the square root of the metric determinant, the square root of determinant of some other tensor field. We analyze the action as a possible alternative or addition to the Einstein gravity. Cosmological consequences of this hypothesis are briefly discussed.

Born-Infeld deformation strategy to smooth theories having divergent solutions is applied to the teleparallel equivalent of General Relativity. The equivalence between teleparallelism and General Relativity is exploited to obtain a deformed theory of gravity based on second order differential equations, since teleparallel Lagrangian is built just from first derivatives of the vierbein. We show that Born-Infeld teleparallelism cures the initial singularity in a spatially flat FRW universe; moreover, it provides a natural inflationary stage without resorting to an inflaton field. The Born-Infeld parameter λ bounds the dynamics of Hubble parameter H(t) and establishes a maximum attainable spacetime curvature.

In this paper we investigate the perturbations by a massless Dirac spinor of a Born–Infeld black hole. The decay rates of the spinor field which is given by the quasinormal mode frequencies are computed using the sixth-order WKB approximation. The behavior of the quasinormal modes with the nonlinear parameter, temperature and charge of the black hole are analyzed in detail. We also compare the decay rates of the Born–Infeld black hole with its linear counterpart Reissner–Nordstrom black hole.

We investigate the possibility that dark energy does not couple to gravitation in the same way as ordinary matter, yielding a violation of the weak and strong equivalence principles on cosmological scales. We build a transient mechanism in which gravitation is pushed away from general relativity (GR) by a Born–Infeld (BI) gauge interaction acting as an "abnormally weighting (dark) energy" (AWE). This mechanism accounts for the Hubble diagram of far-away supernovae by cosmic acceleration and time variation of the gravitational constant while accounting naturally for the present tests on GR.

We examine the (n + 1)-dimensional (n ≥ 3) action in which gravity is coupled to the Born–Infeld nonlinear electrodynamic and a dilaton field. We construct a new (n + 1)-dimensional analytic solution of this theory in the presence of Liouville-type dilaton potentials. These solutions, which describe charged topological dilaton black holes with nonlinear electrodynamics, have unusual asymptotics. They are neither asymptotically flat nor (anti)-de Sitter. The event horizons of these black holes can be an (n - 1)-dimensional positive, zero or negative constant curvature hypersurface. We also analyze the thermodynamics and stability of these solutions and disclose the effect of the dilaton and Born–Infeld fields on the thermal stability in the canonical ensemble.

The field equations associated to Born–Infeld type brane theories are studied by using auxiliary variables. This approach hinges on the fact, that the expressions defining the physical and geometrical quantities describing the worldvolume are varied independently. The general structure of the Born–Infeld type theories for branes contains the square root of a determinant of a combined matrix between the induced metric on the worldvolume swept out by the brane and a symmetric/antisymmetric tensor depending on gauge, matter or extrinsic curvature terms taking place on the worldvolume. The higher-order curvature terms appearing in the determinant form come to play in competition with other effective brane models. Additionally, we suggest a Born–Infeld–Einstein type action for branes where the higher-order curvature content is provided by the worldvolume Ricci tensor. This action provides an alternative description of the dynamics of braneworld scenarios.

We show how the flat spacetime Galileon field theories (FSGFT) in arbitrary dimensions can be obtained through a Born–Infeld (BI) type structure. This construction involves a brane metric and nonlinear combinations of derivatives of a scalar field. Our setup gives rise to some Galileon tensors and vectors useful for the variational analysis which are related to the momentum density of the probe Lovelock branes floating in a N-dimensional flat bulk. We find further that the Noether currents associated to these Galileon theories may be written in terms of such tensors.

In this paper, we have studied QNM modes and absorption cross-sections of Born–Infeld–de Sitter black holes. WKB approximation is employed to compute the QNM modes of massless scalar fields. We have also used null geodesics to compute quasinormal modes in the eikonal approximation. In the eikonal limit, QNMs of black holes are determined by the parameters of the circular null geodesics. Unstable circular null orbits are derived from the effective metric which is obeyed by light rays under the influence of a nonlinear electromagnetic field. Comparison is shown with the QNM of the linear electromagnetic counterpart, the Reissner–Nordström black hole. Furthermore, the null geodesics are employed to compute the absorption cross-sections in the high frequency limit via the sinc approximation.

Gravastar models have recently been proposed as an alternative to black holes, mainly to avoid the problematic issues associated with event horizons and singularities. In this work, a regular variety of gravastar models within the context of Einstein–Born–Infeld (EBI) nonlinear electrodynamics are builded. These models presented here are truly regular in the sense that both the metric and its derivatives are continuous throughout spacetime, contrary to other cases in the literature where matching conditions are necessary in the interior and exterior regions of the event horizon. We investigated the accretion process for spherically symmetric spacetime geometries generated for a nonlinear electromagnetic field where the energy–momentum tensor has the same form that an anisotropic fluid that is the general EBI case. We analyze this procedure using the most general static spherically symmetric metric ansatz. In this theoretical context, we examined the accretion process for specific spherically symmetric compact configuration obtaining the accretion rates and the accretion velocities during the process and the flow of the fluid around the black hole. In addition, we study the behavior of the rate of change of the mass for each chosen metric.

Gravastar models have recently been proposed as an alternative to black holes, mainly to avoid the problematic issues associated with event horizons and singularities. Recently, in [D. J. Cirilo-Lombardo and C. D. Vigh, Int. J. Mod. Phys. D28 (2019) 1950108], a regular variety of gravastar models within the context of Einstein–Born–Infeld (EBI) nonlinear electrodynamics were built. These original models are truly regular in the sense that both the metric and its derivatives are continuous throughout spacetime, contrary to other cases in the literature where matching conditions are necessary in the interior and exterior regions of the event horizon. In this work, in the same theoretical context from [D. J. Cirilo-Lombardo and C. D. Vigh, Int. J. Mod. Phys. D28 (2019) 1950108], we study some optical phenomena, such as the weak gravitational lens for the case of the magnetized plasma and the influence of working with a nonlinear field of BI in observables such as the Einstein ring or the total delay time. These important issues allow us to compare the results obtained in the context of these new static Born–Infeld gravastars with the standard linear ones (e.g. Reissner–Nordström).

Theory of gravitation based on a non-Riemannian geometry with dynamical torsion field is geometrically analyzed. To this end, the simplest Lagrangian density is introduced as a measure (reminiscent of a sigma model) and the dynamical equations are derived. Our goal is to rewrite this generalized affine action in a suitable form similar to the standard Born–Infeld (BI) Lagrangian. As soon as the functional action is rewritten in the BI form, the dynamical equations lead the trace-free GR-type equation and the field equations for the torsion, respectively: both equations emerge from the model in a sharp contrast with other attempts where additional assumptions were heuristically introduced. In this theoretical context, the Einstein $\kappa$, Newton $G$ and the analog to the absolute $b$-field into the standard BI theory all arise from the same geometry through geometrical invariant quantities (as from the curvature $R$). They can be clearly identified and correctly interpreted both physical and geometrically. Interesting theoretical and physical aspects of the proposed theory are given as clear examples that show the viability of this approach to explain several problems of actual interest. Some of them are the dynamo effect and geometrical origin of $\alpha \mathrm{\Omega }$ term, origin of primordial magnetic fields and the role of the torsion in the actual symmetry of the standard model. The relation with gauge theories, conserved currents, and other problems of astrophysical character is discussed with some detail.

In this work, we investigate the quantum dynamics of non-relativistic systems in a Born–Infeld spacetime. We analyze some general scenarios, which concerns the effects of a harmonic oscillator and an inverse square-type potential as well as an Aharonov–Bohm geometric phase. We obtain an analytical solution for the most general case in terms of a confluent Heun function and define the energy spectrum by referring to the ground state, together with its respective eigenfunction. A graphical representation was built so that it was possible to visualize some of the possible energy configurations. For negative values of the Born–Infeld parameter $𝜖<0$, we perform a connection with results of quantum dynamics already investigated in the literature for the Ellis–Bronnikov spacetime.