QUANTUM VIOLATION OF THE EQUIVALENCE PRINCIPLE IN BRANS-DICKE THEORY

We show that quantum fluctuations should violate the weak equivalence principle in the Brans-Dicke theory, which implies that the Jordan fra me can no longer be interpreted as physical. In the Pauli frame the vi olation of the equivalence principle could be attributed to the existe nce of the dilatonic fifth force. We argue that the present fifth forc e experiments could put a much more stringent constraint on the Brans- Dicke coupling constant than accepted so far.