Effective Dilaton Potential in Linearized Gravity

Considering the linearized gravity with matter fields, the effective potential of the ``conformal dilaton'' in the string frame is generated semiclassically by one-loop contribution of heavy matter fields. This in turn generates a nontrivial potential for the physical dilaton in the Einstein frame with the trace of the graviton in the Einstein frame gauged away. The remaining manifest local spacetime symmetry is only the volume preserving diffeomorphism symmetry. The consistency of this procedure is examined and the possibility of spontaneous diffeomorphism symmetry breaking is suggested.Comment: Latex, 11 page

"Vortex Solution in a Multi-Higgs System and Its Physical Implication,"

Classical vortex solutions in $(1+2)$-dimensional multi-Higgs systems are studied. In particular the existence of such a solution requires equal characteristic lengths and a specific relation between the ratio of the two Higgs vacuum expectation values and the couplings in the Higgs potential, if $\lambda_3\neq 0$.Comment: 11pages, CTP-TAMU-73/92 ( The reason why $c_2/c_1$ should be used as an independent input parameter is explained in detail.