http://arxiv.org/abs/1811.02458

Here we follow the mainstream of thinking about physical equivalence of different representations of a theory, regarded as the consequence of invariance of the laws of physics — represented by an action principle and the derived motion equations — under given transformations; be it coordinate, gauge or conformal transformations. Accordingly the conformal transformations’ issue is discussed by invoking the assumed invariance of the laws of physics — in particular the laws of gravity — under conformal transformations of the metric. It is shown that Brans-Dicke and scalar-tensor theories are not well-suited to address physical equivalence of the conformal frames since the corresponding laws of gravity are not invariant under the conformal transformations or Weyl rescalings. The search for conformal symmetry leads us to explore the physical consequences of Weyl-invariant theories of gravity, that represent a natural arena where to discuss on physical equivalence of the conformally related representations.

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I. Quiros and R. Arcia
Wed, 7 Nov 18
70/94

Comments: 20 pag. no figures