Induced Violation of Weak Equivalence Principle in the Brans-Dicke Theory

A quantum correction to the Brans-Dicke theory due to interactions among matter fields is calculated, resulting in violation of WEP, hence giving a constraint on the parameter $\omega$ far more stringent than accepted so far. The tentative estimate gives the lower bounds \gsim 10^{6} and \gsim 10^{8} for the assumed force-range \gsim 1m and \gsim 1AU, respectively.Comment: 7 pages, LaTe

Role of Regularization in Quantum Corrections to the Scalar-Tensor Theories of Gravity

We show that regularizing divergent integrals is crucially important when applied to the loop diagrams corresponding to quantum corrections to the coupling of the ``gravitational" scalar field due to the interaction among matter fields. We use the method of continuous spacetime dimensions to demonstrate that WEP is a robust property of the Brans-Dicke theory beyond the classical level, hence correcting our previous assertion of the contrary. The same technique can be used to yield the violation of WEP when applied to the scale-invariant theory, thus providing another reason for expecting fifth- force-type phenomena.Comment: Latex 12 pages, including 4 eps figure