Curved-space magnetic monopoles

International Journal of Modern Physics, 2019

We study a spontaneously broken Einstein-Yang-Mills-Higgs model coupled via a Higgs portal to an uncharged scalar χ. We present a phase diagram of self-gravitating solutions showing that, depending on the choice of parameters of the χ scalar potential and the Higgs portal coupling constant γ, one can identify different regions: If γ is sufficiently small a χ halo is created around the monopole core which in turn surrounds a black-hole. For larger values of γ no halo exists and the solution is just a black holemonopole one. When the horizon radius grows and becomes larger than the monopole radius solely a black hole solution exists. Because of the presence of the χ scalar a bound for the Higgs potential coupling constant exists and when it is not satisfied, the vacuum is unstable and no non-trivial solution exists. We briefly comment on possible connections of our results with those found in recent dark matter axion models.

Physical Review D, 2001

It is shown that general relativity coupled to nonlinear electrodynamics (NED) with the Lagrangian L(F) , F = Fµν F µν having a correct weak field limit, leads to nontrivial spherically symmetric solutions with a globally regular metric if and only if the electric charge is zero and L(F) tends to a finite limit as F → ∞. Properties and examples of such solutions, which include magnetic black holes and solitonlike objects (monopoles), are discussed. Magnetic solutions are compared with their electric counterparts. A duality between solutions of different theories specified in two alternative formulations of NED (called the F P duality) is used as a tool for this comparison.

Classical and Quantum Gravity, 2002

A single master equation is given describing spin s ≤ 2 test field gauge and tetrad invariant perturbations of the Taub-NUT spacetime. This solution of vacuum Einstein field equations describes a black hole with mass M and gravitomagnetic monopole moment. This equation can be separated in its radial and angular parts. The behaviour of the radial functions at infinity and near the horizon is studied. The angular equation, solved in terms of hypergeometric functions, can be related both to spherical harmonics of suitable weight, resulting from the coupling of the spin-weight of the field and the gravitomagnetic monopole moment of the spacetime and to the total angular momentum operator associated with the spacetime's rotational symmetry. The results are compared with the Teukolsky master equation for the Kerr spacetime.

Physical Review D, 2011

A magnetic-monopole solution of a non-Abelian gauge theory as proposed by 't Hooft and Polyakov is studied in the Vaidya spacetime. We find that the solutions of Einstein equations generates a geometry of the Bonnor-Vaidya corresponding to magnetically charged null fluid with Higgs field contributing a cosmological term. In the absence of the scalar fields the corresponding Wu-Yang solution of the gauge theory still generates the Bonnor-Vaidya geometry, but with no cosmological term.

arXiv: General Relativity and Quantum Cosmology, 2020

We introduce the concept of emergent monopoles, weaved out of space-time geometry in vacuum. These are constructed to be nonsingular classical solutions of gravitational field equations, where the metric necessarily exhibits a non-invertible phase at the core. If this is the only possible realization of monopoles in nature, they can never be observed in principle. This geometry is shown to have a unique continuation to an Einsteinian phase, namely, the Reissner-Nordstrom spacetime. In addition, we provide a new interpretation to the monopole charge in terms of a geometric invariant in gravity theory. A topological quantization law is also presented.

The European Physical Journal C, 2017

In this paper the f (R) global monopole is reexamined. We provide an exact solution for the modified field equations in the presence of a global monopole for regions outside its core, generalizing previous results. Additionally, we discuss some particular cases obtained from this solution. We consider a setup consisting of a possible Schwarzschild black hole that absorbs the topological defect, giving rise to a static black hole endowed with a monopole's charge. Besides, we demonstrate how the asymptotic behavior of the Higgs field far from the monopole's core is shaped by a class of spacetime metrics which includes those ones analyzed here. In order to assess the gravitational properties of this system, we analyse the geodesic motion of both massive and massless test particles moving in the vicinity of such configuration. For the material particles we set the requirements they have to obey in order to experience stable orbits. On the other hand, for the photons we investigate how their trajectories are affected by the gravitational field of this black hole.

Physical Review D, 2014

Higgs inflation has received a remarkable attention in the last few years due to its simplicity and predictive power. The key point of this model is the nonminimal coupling to gravity in unitary gauge. As such, this theory is in fact a scalar-tensor modification of gravity that needs to be studied also below the energy scales of inflation. Motivated by this goal, we study in great analytical and numerical detail the static and spherically symmetric solutions of the equations of motion in the presence of standard baryonic matter, called "Higgs monopoles" and presented in [1]. These particlelike solutions may arise naturally in tensor-scalar gravity with mexican hat potential and are the only globally regular asymptotically flat solutions with finite classical energy. In the case when the parameters of the potential are taken to be the ones of the standard model, we find that the deviations from general relativity are extremely small, especially for bodies of astrophysical size and density. This allows to derive a simplified description of the monopole, for which the metric inside the spherical matter distribution can be approximated by the standard metric of general relativity. We study how the properties of these monopoles depend on the strength of the nonminimal coupling to gravity and on the baryonic mass and compactness. An important and original result is the existence of a mechanism of resonant amplification of the Higgs field inside the monopole that comes into play for large nonminimal coupling. We show that this mechanism might degenerate into divergences of the Higgs field that reveal the existence of forbidden combinations of radius and baryonic energy density.

2008

We show that gravity cures the infra-red divergence of the Yang monopole when a proper definition of conserved quantities in curved backgrounds is used, i.e. the gravitating Yang monopole in cosmological Einstein theory has a finite mass in generic even dimensions (including time). In addition, we find exact Yang-monopole type solutions in the cosmological Einstein-Gauss-Bonnet-Yang-Mills theory and briefly discuss their properties.

Classical and Quantum Gravity, 2006

The (2k + 2)-dimensional Einstein-Yang-Mills equations for gauge group SO(2k) (or SU(2) for k = 2 and SU(3) for k = 3) are shown to admit a family of spherically-symmetric magnetic monopole solutions, for both zero and non-zero cosmological constant Λ, characterized by a mass m and a magnetic-type charge. The k = 1 case is the Reissner-Nordstrom black hole. The k = 2 case yields a family of self-gravitating Yang monopoles. The asymptotic spacetime is Minkowski for Λ = 0 and anti-de Sitter for Λ < 0, but the total energy is infinite for k > 1. In all cases, there is an event horizon when m > m c , for some critical mass m c , which is negative for k > 1. The horizon is degenerate when m = m c , and the near-horizon solution is then an adS 2 × S 2k vacuum.

Annals of the New York Academy of Sciences, 1984