Searcharxiv⌕ Search

arXiv subjects

Eugen Radu

Publications and source records attributed to Eugen Radu.

264 records · Page 15Linked to original sources
arXiv2003

Boson stars with negative cosmological constant

We consider boson star solutions in a $D$-dimensional, asymptotically anti-de Sitter spacetime and investigate the influence of the cosmological term on their properties. We find that for $D>4$ the boson star properties are close to those in four dimensions with a vanishing cosmological constant. A different behavior is noticed for the solutions in the three dimensional case. We establish also the non-existence of static, spherically symmetric black holes with a harmonically time-dependent complex scalar field in any dimension greater than two.

gr-qc↗
arXiv2003

Gravitating nonabelian solutions with NUT charge

We argue that the Einstein-Yang-Mills theory presents nontrivial solutions with a NUT charge. These solutions approach asymptotically the Taub-NUT spacetime. They are characterized by the NUT parameter, the mass and the node numbers of the magnetic potential and present both electric and magnetic potentials.=0D The existence of nontrivial Einstein-Yang-Mills solutions with NUT charge in the presence of a negative cosmological constant is also discussed. We use the counterterm subtraction method to calculate the boundary energy-momentum tensor and the mass of these configurations. Also, dyon black hole solutions with nonspherical event horizon topology are shown to exist for a negative cosmological constant.

hep-th↗
arXiv2002

Rotating Yang-Mills dyons in anti-de Sitter spacetime

We construct new axially symmetric solutions of SU(2) Yang-Mills theory in a four dimensional anti-de Sitter spacetime. Possessing nonvanishing nonabelian charges, these regular configurations have also a nonzero angular momentum. Numerical arguments are also presented for the existence of rotating solutions of Einstein-Yang-Mills equations in an asymptotically anti-de Sitter spacetime.

gr-qc↗
arXiv2002

Magnetic charge, angular momentum and negative cosmological constant

We argue that there are no axially symmetric rotating monopole solutions for a Yang-Mills-Higgs theory in flat spacetime background. We construct axially symmetric Yang-Mills-Higgs solutions in the presence of a negative cosmological constant, carrying magnetic charge $n$ and a nonvanishing electric charge. However, these solution are also nonrotating.

hep-th↗
arXiv2002

New nonabelian solutions in D=4, N=4 gauged supergravity

In this paper we look for static, purely magnetic, nonabelian solutions with unusual topology in the context of N=4 Freedman-Schwarz supergravity in four dimensions.Two new exact solutions satisfying first order Bogomol'nyi equations are discussed.The main characteristics of the general solutions are presented and differences with respect to the spherically symmetric case are studied. We argue that all solutions present naked singularities.

gr-qc↗
arXiv2001

Quantum effects in a rotating spacetime

The behavior of a arbitrary coupled quantum scalar field is studied in the background of the Gödel spacetime. Closed forms are derived for the effective action and the vacuum expectation value of quadratic field fluctuations by using $ζ$-function regularization. Based on these results, we argue that causality violation presented in this spacetime can not be removed by quantum effects.

gr-qc↗
arXiv2001

On rotating regular nonabelian solutions

A general relation for the total angular momentum of a regular solution of the Einstein-Yang-Mills-Higgs equations is derived. Two different physical configurations, rotating dyons and rotating magnetic dipoles are discussed as particular cases. The issue of rotating pure Einstein-Yang-Mills regular solutions is addressed as well. Based on the results, we conjecture the absence of rotating regular solitons with a net magnetic charge.

gr-qc↗
arXiv2001

Static axially symmetric solutions of Einstein-Yang-Mills equations with a negative cosmological constant: the regular case

Numerical solutions of the Einstein-Yang-Mills equations with a negative cosmological constant are constructed. These axially symmetric solutions approach asymptotically the anti-de Sitter spacetime and are regular everywhere. They are characterized by the winding number $n>1$, the mass and the non-Abelian magnetic charge. The main properties of the solutions and the differences with respect to the asymptotically flat case are discussed. The existence of axially symmetric monopole and dyon solutions in fixed anti-de Sitter spacetime is also discussed.

gr-qc↗
arXiv2001

New hairy black holes with negative cosmological constant

Black hole solutions with nonspherical event horizon topology are shown to exist in an Einstein-Yang-Mills theory with negative cosmological constant. The main characteristics of the solutions are presented and differences with respect to the spherically symmetric case are studied. The stability of these configurations is also addressed.

gr-qc↗
arXiv2001

Gravitating sphalerons and sphaleron black holes in asymptotically anti-de Sitter spacetime

Numerical arguments are presented for the existence of spherically symmetric regular and black hole solutions of the EYMH equations with a negative cosmological constant. These solutions approach asymptotically the anti-de Sitter spacetime. The main properties of the solutions and the differences with respect to the asymptotically flat case are discussed. The instability of the gravitating sphaleron solutions is also proven.

gr-qc↗
arXiv2001

Regular and black-hole solutions of the Einstein-Yang-Mills-Higgs equations; the case of nonminimal coupling

Regular and black-hole solutions of the spontaneously broken Einstein-Yang-Mills-Higgs theory with nonminimal coupling to gravity are shown to exist. The main characteristics of the solutions are presented and differences with respect to the minimally coupled case are studied. Since negative energy densities are found to be possible, traversable wormhole solutions might exist. We prove that they are absent.

hep-th↗