Yosef Verbin

Complete Classification of the String-like Solutions of the Gravitating Abelian Higgs Model

The static cylindrically symmetric solutions of the gravitating Abelian Higgs model form a two parameter family. In this paper we give a complete classification of the string-like solutions of this system. We show that the parameter plane is composed of two different regions with the following characteristics: One region contains the standard asymptotically conic cosmic string solutions together with a second kind of solutions with Melvin-like asymptotic behavior. The other region contains two types of solutions with bounded radial extension. The border between the two regions is the curve of maximal angular deficit of 2�.

Spherical Structures in Conformal Gravity and its Scalar-Tensor Extension

We study spherically symmetric structures in conformal gravity and in a scalar-tensor extension and gain some more insight about these gravitational theories. In both cases we analyze solutions in two systems: perfect fluid solutions and boson stars of a self-interacting complex scalar field. In the purely tensorial (original) theory we find in a certain domain of parameter space finite mass solutions with a linear gravitational potential but without a Newtonian contribution. The scalar-tensor theory exhibits a very rich structure of solutions whose main properties are discussed. Among them, solutions with a finite radial extension, open solutions with a linear potential and logarithmic modifications and also a (scalar-tensor) gravitational soliton. This may also be viewed as a static self-gravitating boson star in purely tensorial conformal gravity.

Perfect fluid spherically symmetric solutions in massive gravity

We study spherically-symmetric solutions in Massive Gravity generated by matter sources with polytropic equation of state. We concentrate in the non-perturbative regime where the mass term non-linearities are important, and present the main features of the solutions.

Quantized non-abelian wormholes

Abstract Novel wormhole configurations are derived in the context of Einstein-Yang-Mills theory. The wormhole size is exponentially quantized. There is no abelian analogue.

Wormholes from conformal matter

Abstract Novel wormhole configurations are derived as solutions to the Einstein equations with “ordinary” conformal matter: (1) SU(2) gauge fields; (2) conformally coupled scalar. Due to the conformal symmetry, we find in both cases the same space with vanishing Ricci scalar and two asymptotically euclidean regions. Addition of a positive cosmological constant is also considered and wormhole characteristics are discussed.

Superconducting and Spinning Non-Abelian Flux Tubes

AbstractWe find new non-Abelian flux tube solutions in a model of N f scalar fields in the fundamentalrepresentation of SU(N)×U(1) with N ≤ N f (the “extended non-Abelian Higgs model”), andstudy their main properties. Among the solutions there are spinning strings as well as supercon-ducting ones. The solutions exist only in a non trivial domain of the parameter space definedby the ratio between the SU(N) and U(1) coupling constants, the scalar self-interaction cou-pling constants, the magnetic fluxes (Abelian as well as non-Abelian) and the “twist parameter”which is a non-trivial relative phase of the Higgs fields. 1 Introduction Non-Abelian stringlike solutions have a long history which starts already in 1973 with the Nielsen-Olesen seminal paper [1]. Several general discussions were published [1, 2, 3, 4] and explicit solutions(numerical of course) were obtained [5, 6, 7, 8, 9, 10, 11] for an SU(N) gauge theory with Higgsfields in the adjoint representation which completely break the symmetry. However, the major partof the activity in the field of cosmic strings [12] was concentrated on their Abelian counterparts. One

Cosmic strings in the Abelian Higgs model with conformal coupling to gravity

Cosmic string solutions of the abelian Higgs model with conformal coupling to gravity are shown to exist. The main characteristics of the solutions are presented and the differences with respect to the minimally coupled case are studied. An important difference is the absence of Bogomolnyi cosmic string solutions for conformal coupling. Several new features of the abelian Higgs cosmic strings of both types are discussed. The most interesting is perhaps a relation between the angular deficit and the central magnetic field which is bounded by a critical value.

Self-gravitating spherical solutions of the nonminimally coupled non-Abelian Higgs model

Motivated by the Higgs Inflation scenario, we study static spherically-symmetric solutions of the non-Abelian Higgs model coupled non-minimally to Gravity. We find solutions for the self-gravitating sphaleron as well as monopole-like solutions and study the impact of the non-minimal coupling on their properties. Finally we discuss shortly the possibility that these solutions interact gravitationally with star-like objects like boson stars.

Boundary conditions and modes of the vertically hanging chain

The hanging chain is a very instructive system for demonstrating more advanced methods and ideas for the analysis of normal modes of one-dimensional systems, beyond the standard ordinary (horizontal) string. Accordingly, the normal modes of the hanging chain are analysed with several cases of boundary conditions and are compared to the ordinary vibrating string.

Exact string-like solutions in conformal gravity

The cylindrically-symmetric static vacuum equations of Conformal Gravity are solved for the case of additional boost symmetry along the axis. We present the complete family of solutions which describe the exterior gravitational field of line sources in Conformal Gravity. We also analyze the null geodesics in these spaces.