We study holographic superconductors in Einstein-Gauss-Bonnet gravity. consider two particular backgrounds: a $d$-dimensional Gauss-Bonnet-AdS black hole and soliton. discuss detail the effects that mass of scalar field, Gauss-Bonnet coupling dimensionality AdS space have on condensation formation conductivity. also ratio ${\ensuremath{\omega}}_{g}/{T}_{c}$ for various masses field couplings.

We study certain bi-scalar-tensor theories emanating from conformal symmetry requirements of Horndeski's four-dimensional action. The former scalar is a Galileon with shift whereas the latter adjusted to have higher order coupling. Employing techniques local Weyl geometry terms are thus constructed be conformally invariant. combined and partial action, allow us construct exact black hole solutions. holes initially found planar horizon embedded in anti de Sitter space can accommodate electric...

Recently new scalarized black hole solutions were constructed in the extended scalar-tensor-Gauss-Bonnet gravity, where scalar field is sourced by curvature of spacetime via Gauss-Bonnet invariant. A natural extension these results to consider case nonzero charge. In addition we have explored a large set coupling functions between invariant and field, that was not done until now even uncharged case, order understand better behavior deviations from pure general relativity. The show charge two...

In this work we discuss the polarization contents of Einstein-\ae{}ther theory and generalized tensor-vector-scalar (TeVeS) theory, as both theories have a normalized timelike vector field. We derive linearized equations motion around flat spacetime background using gauge-invariant variables to easily separate physical degrees freedom. find plane wave solutions identify polarizations by examining geodesic deviation equations. that there are five in six TeVeS theory. particular, transverse...

Using Euclidean methods we investigate the thermodynamics of stealth black hole solutions, which are solutions that geometrically indistinguishable from those general relativity; however, they accompanied by a nontrivial additional field does not backreact to metric. We find in general, one can observe shifts mass and/or entropy such holes; hence, at least thermodynamic level, may be distinguished relativity. also point out an example, , where scalar accompany (A)dS-Schwarzschild without...

We construct cubic gravity and its $f(P)$ extension we investigate their early- late-time cosmological applications. Cubic is based on a particular invariant $P$, constructed from contractions of the Riemann tensor, under three requirements: (i) resulting theory possesses spectrum identical to that general relativity, (ii) it neither topological nor trivial in four dimensions, (iii) defined such independent dimensions. Relaxing last condition restricting parameters can obtain second-order...

It was recently shown that Strong Cosmic Censorship might be violated for near-extremally-charged black holes in 4-dimensional de Sitter space under scalar perturbations. Here, we extend the study of neutral massless perturbations higher dimensions and discuss dimensional influence on validity hypothesis. By giving an elaborate description Reissner-Nordstr\"{o}m-de $d=4,5$ $6$ conclude is near extremality.

In this work we consider a generalized Bronnikov-Ellis wormhole and the tideless Morris-Thorne study propagation of massive scalar fields. We calculate quasinormal frequencies using Wentzel-Kramers-Brillouin method pseudospectral Chebyshev show presence an anomalous decay rate for modes in wormhole. However, such behavior is avoided fundamental mode background.

We derive an exact wormhole spacetime supported by a phantom scalar field in the context of $f(\mathsf{R})$ gravity theory. Without specifying form function, self-interacts with mass term potential which is derived from equation and resulting model curvature modified presence it free ghosts avoids tachyonic instability.

We discuss thermodynamical stability for hairy black hole spacetimes, viewed as defects in the parameter space, taking into account backreaction of a secondary hair onto spacetime geometry, which is modified nontrivially. derive, model independent way, conditions with to reach stable thermal equilibrium heat bath. Specifically, if scalar hair, induced by interactions matter fields quadratic-curvature corrections, produces an inner horizon deformed thermodynamically configuration will be...

We discuss spontaneous scalarization of the Reissner-Nordstr\"om black hole in presence higher derivative gauge field corrections that arise context string, as well higher-dimensional more fundamental gravity theories. Our theory admits solution at scalar vacuum ($\ensuremath{\phi}=0$), and we find order correction term results tachyonic instability our system once coupling function satisfies condition its second is positive appropriate parameter space. branches do not end with an extremal...

We consider a gravitating system of vanishing cosmological constant consisting an electromagnetic field and scalar coupled to the Einstein tensor. A Reissner–Nordström black hole undergoes second-order phase transition hairy generally anisotropic hair at certain critical temperature which we compute. The no-hair theorem is evaded due coupling between Within first-order perturbative approach, calculate explicitly properties configuration near show that it energetically favourable over...

We study spherically symmetric solutions in scalar-torsion gravity theories which a scalar field is coupled to torsion with derivative coupling. obtain the general equations from we extract decoupled master equation, solution of leads specification all other unknown functions. first an exact represents new wormholelike dressed regular field. Then, find large distance linearized space asymptotically anti--de Sitter.

We study the entanglement entropy as a probe of proximity effect superconducting system by using gauge/gravity duality in fully back-reacted gravity system. While phase is less than normal phase, we find that near contact interface to has different behavior due leakage Cooper pairs phase. verify this calculating conductivity boundary interface.

We study the holographic dual description of a superconductor in which gravity sector consists Maxwell field and charged scalar except its minimal coupling to it is also coupled kinematically Einstein tensor. As strength new increased, critical temperature below condenses lowering, condensation gap decreases faster than temperature, width not proportional size condensate at low temperatures tends zero for strong coupling. These effects are result presence tensor bulk, provide impurities...

The strong cosmic censorship hypothesis has recently regained a lot of attention in charged and rotating black holes immersed de Sitter space. Although the picture seems to be clearly leaning towards validity Kerr-de geometries, Reissner-Nordstr\"{o}m-de appear serious counter-examples. Here, we perform another test by using scalar field perturbation non-minimally coupled Einstein tensor propagating on spacetimes. Such non-minimal derivative coupling is characteristic Horndeski scalar-tensor...

Abstract We report exact black hole solutions in asymptotically flat or (A)dS four-dimensional spacetime with a conformally coupled self-interacting scalar field f ( R ) gravity. first consider the model $$f(R) = -2\alpha \sqrt{R}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mi>f</mml:mi> <mml:mo>(</mml:mo> <mml:mi>R</mml:mi> <mml:mo>)</mml:mo> </mml:mrow> <mml:mo>=</mml:mo> <mml:mo>-</mml:mo> <mml:mn>2</mml:mn> <mml:mi>α</mml:mi> <mml:msqrt> </mml:msqrt>...

Chern-Simons gravity rotating Kerr-type black hole solutions are revisited from the point of view their scalarization, namely examining backreaction pseudoscalar axion fields on geometry. To lowest order in an angular momentum expansion, and a long range approximation for both field configuration its onto metric, such had been discussed first time context string theory. In this work, we extend analysis to give analytic expressions slowly holes outside horizon, which formally include all...

We discuss exact regular compact object solutions in higher-dimensional extensions of general relativity sourced by a phantom scalar field arbitrary $D$ spacetime dimensions ($D>2$), for which central singularity is absent. follow bottom-up approach, means which, imposing the desired form solution to metric function, we derive self-interaction potential, appears depend on both scalar-hair charge and black-hole mass. this context validity first law thermodynamics such systems. Consistency...