Gravitational and topological effects on $\sqrt{-F^2}$ confinement dynamics

Abstract

We present a review, of recent developments on non-linear gauge theory containing a √ −F 2 term coupled to gravity. We start by showing some of the confining features of this theory in flat space-time. We then consider the coupling, of this non-linear term, to gravity and discuss two types of spherically symmetric solutions. One of them has a tube topology, that is M 2 × S 2 , or of the Levi-Civitta-Robinson-Berttoti (LCRB) type, where the metric coefficient g θθ is a constant. The other type of solutions, Reissner-Nordström-de-Sitter (RNdS), with g θθ = r 2 , where r is a radial variable allowed to have all values from zero to infinity. Next we consider the matching of these solutions via light-like, and subsequently, time-like membranes and show the topologically induced effects of "Hiding of Charge", where a charged particle can appear neutral to an external observer looking at it from the RNdS region, and the "Confining of charge" in a wormhole throat, where two opposite charges are at the opposite sides of a wormhole throats. We proceed with some applications to extended theories of general relativity, in the form of quadratic gravity model (F (R)), then wormholes arise naturally from the non-linear electromagnetic field rather than requiring exotic matter to generate a pre-designed wormhole geometry (Morris-Thorne approach), in another model considered here we have, in addition to quadratic gravity, a dilaton filed (φ), where we find wormhole solutions with de-Sitter asymptotics, and confinement-deconfinement transition effects as function of the dilaton vacuum expectation value. The last application we present is to the "Two Measure theory", where in addition to the metric volume element, √ −g, we consider a new, metric independent, volume element Φ. Finally we conclude and summarize our findings.

Nonlinear electrodynamics effects on the black hole shadow, deflection angle, quasinormal modes and greybody factors

“…15. The behaviour of the tails of the l = 0 waveforms, given in (14). They follow the same paths, unlike [135], the behaviour of the DL-NED black hole is very similar to the Schwarzschild black hole.…”

“…In the following figures (14,16,17), we show the |Ψ| and ln |Ψ| for l = 0, 1, 2, for both the Schwarzschild potential and the DL-NED potential. The waveforms are essentially identical, but there are slight differences in the oscillation frequencies, which are clearer to see in the logarithmic plots.…”

Black hole with confining electric potential in scalar-tensor description of regularized 4-dimensional Einstein-Gauss-Bonnet gravity

“…On the other hand, we show new effects of 4D EGB gravity by coupling the confining potential which generates nonlinear gauge field system. This is also clear way to generate dynamically the cosmological constant through the non-Maxwell gauge fields [11][12][13][14][15][16]. The metric function for the derived black hole solution in Eq.…”

“…It is crucial to stress that the Lagrangian contains both the usual Maxwell term as well as a non-analytic function of F 2 and thus it is a non-standard form of nonlinear electrodynamics. The energy-momentum tensor of the nonlinear gauge field is [11][12][13][14][15][16][17]:…”

“…It was shown that the nonlinear terms in NGF interpret as "infrared counterterms". Along with the Maxwell term, one can add a square root of the field strength squared, and construct a special type of non-Maxwell nonlinear effective gauge field model as given by [11][12][13][14][15][16][17]:…”