SYMMETRY-BREAKING IN DYNAMICAL SPACETIMES

The behaviour of scalar electrodynamics under symmetry breaking by the Higgs mechanism is studied in a class of dynamical spacetimes-those h aving a Bianchi type I symmetry-which includes the spatially flat Robe rtson-Walker spacetimes. The Einstein equations are used to obtain the effective Lagrangian, from which it is shown that either the gauge fi eld does not become massive during symmetry breaking (in marked contra st with the case in which the background spacetime is static), or the symmetry breaking chooses not only a direction in the phase space of t he Higgs field, but also a spatial direction in the spacetime sections .