Bound monopoles in Brans-Dicke theory

TL;DR

This paper investigates axially symmetric multimonopoles in Brans-Dicke theory, revealing how gravitational coupling and Brans-Dicke parameter influence monopole solutions and their collapse into black holes.

Contribution

It extends the study of multimonopoles to Brans-Dicke theory, showing their existence at higher gravitational couplings and analyzing their collapse behavior.

Findings

Monopoles exist for higher gravitational couplings than in Einstein gravity.

Solutions collapse into extremal Reissner-Nordstrom black holes at large couplings.

Attractive monopole interactions weaken as the Brans-Dicke parameter decreases.

Abstract

We consider axially symmetric SU(2) Yang-Mills-Higgs (YMH) multimonopoles in Brans-Dicke theory for winding number n > 1. In analogy to the spherically symmetric n=1 solutions, we find that the axially symmetric solutions exist for higher values of the gravitational coupling than in the pure Einstein gravity case. For large values of the gravitational coupling, the solutions collapse to form a black hole which outside the horizon can be described by an extremal Reissner-Nordstrom solution. Similarly as in the pure Einstein gravity case, like-charged monopoles reside in an attractive phase in a limited domain of parameter space. However, we find that the strength of attraction is decreasing for decreasing Brans-Dicke parameter.