## Pseudo Weyl invariance is still anomalous    [PDF]

Enrique Alvarez, Mario Herrero-Valea
A Weyl invariant extension of Einstein gravity is studied. It simply consists in the group averaging of Einstein's action under Weyl transformations. Contradicting cherished beliefs, a conformal anomaly is found in the trace of the equations of motion if diffeomorphism invariance is to be a symmetry of the quantum theory. It is however possible to keep Weyl invariance as a {\em bona fide} symmetry at the price of losing full diffeomorphism invariance. This is what happens in {\em unimodular gravity}, a closely related theory.
View original: http://arxiv.org/abs/1307.2060