Non-covariance of the dressed-metric approach in loop quantum cosmology

Abstract

The dressed-metric approach is shown to violate general covariance by demonstrating that it cannot have an off-shell completion in which the correct infinitesimal relations of space-time hypersurface deformations are realized. The main underlying reason -- a separation of background degrees of freedom and modes of inhomogeneity that is incompatible with covariance -- is shared with other approaches such as hybrid loop quantum cosmology.