Global monopole in scalar tensor theory

The well known monopole solution of Barriola and Vilenkin (BV) resulting from the breaking of a global SO(3) symmetry is extended in general relativity along with a zero-mass scalar field and also in the Brans-Dicke (BD) theory of gravity. In the case of BD theory, the behaviour of spacetime and other variables such as the BD scalar field and the monopole energy density have been studied numerically. For a monopole along with a zero-mass scalar field, exact solutions are obtained and, depending upon the choice of arbitrary parameters, the solutions either reduce to the BV case or to a pure scalar field solution as special cases. It is interesting to note that unlike the BV case the global monopole in the BD theory does exert a gravitational pull on a test particle moving in its spacetime.