Critical behavior in the Brans-Dicke theory of gravitation

The collapse of a massless scalar field in the Brans-Dicke theory of gravitation is studied both under self-similar symmetry and under asymptotic flat boundary conditions. In the self-similar case, we find the critical exponent depends on omega, namely 1/2+/-1/2 root 2 omega+3. In the case of the asymptotic Aat space-time, we use numerical method and find that the critical solution shows discrete selfsimilarity and that the critical exponent depends on omega, while the echoing parameter depends weakly on it.