UPPER LIMIT TO OMEGA(B) IN SCALAR-TENSOR GRAVITY THEORIES

In a previous paper, we pointed out the existence of some particular s calar-tensor gravity theories that are able to relax the nucleosynthes is constraint on the cosmic baryonic density. In this paper, we presen t an exhaustive study of primordial nucleosynthesis in the framework o f such theories, taking into account the currently adopted observation al constraints. We show that a wide class of theories allows for a bar yonic density very close to that needed for closure of the universe. T his class of theories converges soon enough toward general relativity and, hence, is compatible with all solar system and binary pulsar grav itational tests. In other words, we show that primordial nucleosynthes is does not always impose a very stringent bound on the baryon contrib ution to the density parameter.