Conformal form-invariant parametrization of scalar-tensor gravity theories: A critical analysis

Abstract: Based on the recent result that the action of matter fields is conformal form-invariant in its standard form and on the active and passive approaches to conformal transformations, we review the conformal form-invariant parametrization of scalar-tensor gravity theories. We investigate whether this parametrization is actually different from other existing parametrizations. We also check the accuracy of the claim that the classical physical predictions of these theories are conformal-frame invariants.