A Self-gravitating Dirac-Born-Infeld Global Monopole

Abstract

We generalize the field theory of global monopole to Dirac-Born-Infeld(DBI) field and investigate the gravitational property of a DBI global monopole in four-dimensional spherically symmetric spacetime. The coupled equations for the metric and the DBI scalar field are solved asymptotically and numerically. It is found that, just as a canonical global monopole, the gravitational effect of DBI global monopole is equivalent to that of a deficit solid angle in the metric plus a negative mass at the origin. However, compared with a canonical global monopole, for the same false vacuum and symmetry breaking scale, a DBI global monopole has a relatively smaller core and a larger absolute value of effective mass. Thus, it can give out a larger deflect angle when the light passing by. Especially, when the scale of warp factor is small enough, the effective mass of a DBI global monopole does not depend apparently on the value of the false vacuum, which is qualitatively different from that of a canonical global monopole.