Seminar Perturbatively renormalizable quantum gravity

Contatto di riferimento: Barbara Simoni

Partecipanti: Prof. Tim Morris (Università’ di Southampton -UK)

Abstract: The Wilsonian renormalization group (RG) requires Euclidean signature. The conformal factor of the metric then has a wrong-sign kinetic term, which has a profound effect on its RG properties. In particular around the Gaussian fixed point, it supports a Hilbert space of renormalizable  interactions involving arbitrarily high powers of the gravitational fluctuations.

These interactions are characterised by being exponentially  suppressed for large field amplitude, perturbative in Newton's constant but non-perturbative in Planck's constant.
By taking a limit to the boundary of the Hilbert space, diffeomorphism invariance is recovered whilst retaining renormalizability.
Thus the so-called conformal factor instability points the way to constructing a perturbatively renormalizable theory of quantum gravity.