MULTIPLE FIELD SCALAR-TENSOR THEORIES OF GRAVITY AND COSMOLOGY

We consider multiple scalar fields coupled to gravity, with special at tention given to two-field theories. First, the conditions necessary f or these theories to exactly meet solar system tests are given. We fin d, in particular, that these constraints require that some scalar kine tic terms be non-positive-definite. Next, we investigate the cosmologi cal evolution of the fields to see if these conditions can be met. Sol utions are found in the dust era, as well as radiation- and cosmologic al-constant-dominated epochs. The possibility of inflation in these th eories is discussed. While power law growth of the scalar fields can y ield the appropriate conditions to meet solar system constraints, thes e solutions are unstable.