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Bronnikov K.A.,Institute of Gravitation and Cosmology | Zaslavskii O.B.,University of Kharkiv
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2011

We study the conditions of a possible static equilibrium between spherically symmetric, electrically charged or neutral black holes and ambient matter. The following kinds of matter are considered: (1) neutral and charged matter with a linear equation of state pr=wρ (for neutral matter the results of our previous work are reproduced), (2) neutral and charged matter with pr∼ρm, m>1, and (3) the possible presence of a "vacuum fluid" (the cosmological constant or, more generally, anything that satisfies the equality T00=T11 at least at the horizon). We find a number of new cases of such an equilibrium, including those generalizing the well-known Majumdar-Papapetrou conditions for charged dust. It turns out, in particular, that ultraextremal black holes cannot be in equilibrium with any matter in the absence of a vacuum fluid; meanwhile, matter with w>0, if it is properly charged, can surround an extremal charged black hole. © 2011 American Physical Society.

Bronnikov K.A.,Institute of Gravitation and Cosmology | Sushkov S.V.,Tatar State University of Humanities and Education
Classical and Quantum Gravity | Year: 2010

We construct examples of static, spherically symmetric wormhole solutions in general relativity with a minimally coupled scalar field whose kinetic energy is negative in a restricted region of space near the throat (of arbitrary size) and positive far away from it. Thus in such configurations a 'ghost' is trapped in the strong-field region, which may in principle explain why no ghosts are observed under usual conditions. Some properties of general wormhole models with the field are revealed: it is shown that (i) trapped-ghost wormholes are only possible with nonzero potentials V(); (ii) in wormholes with two asymptotically flat regions, a nontrivial potential V() has an alternate sign and (iii) a wormhole with two asymptotically flat regions which is mirror symmetric with respect to its throat has necessarily a zero Schwarzschild mass at both asymptotics. © 2010 IOP Publishing Ltd.

Bolokhov S.V.,PFUR | Bronnikov K.A.,Institute of Gravitation and Cosmology | Rubin S.G.,National Research Nuclear University MEPhI
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2011

The Higgs boson of the standard model is described by a set of off-diagonal components of the multidimensional metric tensor, as well as the gauge fields. In the low-energy limit, the basic properties of the Higgs boson are reproduced, including the shape of the potential and interactions with the gauge fields of the electroweak part of the standard model. © 2011 American Physical Society.

Ivashchuk V.D.,Institute of Gravitation and Cosmology
European Physical Journal C | Year: 2016

We consider a gravitational model in dimension D with several forms, l scalar fields and a Λ -term. We study cosmological-type block-diagonal metrics defined on a product of an 1-dimensional interval and n oriented Einstein spaces. As an electromagnetic composite brane ansatz is adopted and certain restrictions on the branes are imposed the conformally covariant Wheeler–DeWitt (WDW) equation for the model is studied. Under certain restrictions, asymptotic solutions to the WDW equation are found in the limit of the formation of the billiard walls. These solutions reduce the problem to the so-called quantum billiard in (n+ l- 1) -dimensional hyperbolic space. Several examples of quantum billiards in the model with electric and magnetic branes, e.g. corresponding to hyperbolic Kac–Moody algebras, are considered. In the case n= 2 we find a set of basis asymptotic solutions to the WDW equation and derive asymptotic solutions for the metric in the classical case. © 2016, The Author(s).

Bronnikov K.A.,Institute of Gravitation and Cosmology | Elizalde E.,Consejo Superior de Investigaciones Cientificas ICE CSIC IEEC Campus UAB
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2010

The properties of static, spherically symmetric configurations are considered in the framework of two models of nonlocally corrected gravity, suggested in S. Deser and R. Woodard, Phys. Rev. Lett. 99, 111301 (2007)PRLTAO0031-900710.1103/PhysRevLett.99.111301 and S. Capozziello, Phys. Lett. B 671, 193 (2009)PYLBAJ0370-269310.1016/j.physletb.2008.11.060. For the first case, where the Lagrangian of nonlocal origin represents a scalar-tensor theory with two massless scalars, an explicit condition is found under which both scalar fields are canonical (nonphantom). If this condition does not hold, one of the fields exhibits a phantom behavior. Scalar-vacuum configurations then behave in a manner known for scalar-tensor theories. In the second case, the Lagrangian of nonlocal origin exhibits a scalar field interacting with the Gauss-Bonnet (GB) invariant and contains an arbitrary scalar field potential. It is found that the GB term, in general, leads to violation of the well-known no-go theorems valid for minimally coupled scalar fields in general relativity. It is shown, however, that some configurations of interest are still forbidden-whatever be the scalar field potential and the GB-scalar coupling function, namely, "force-free" wormholes (such that gtt=const) and black holes with higher-order horizons. © 2010 The American Physical Society.

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