Ph.D in Physics

 

Seminario  26° ciclo per presentazione tesi finale

26/02/2014 - 16:30
AULA C (piano terra) Dip.to  Matematica e  Fisica,  Via della Vasca Navale n. 84

"Renormalization group flow of scalar models in gravity"

Dott. Filippo Guarnieri

Abstract:
We will employ the renormalization group (RG) to study two quantum gravity approaches that have received recently much attention: the asymptotic safety scenario for gravity and the Horava-Lifshitz quantum gravity. We will focus in particular on the quantization of scalar models of gravity obtained, on the one hand, as conformal reductions of gravitational theories and on the other hand as dynamically equivalent theories (i.e.
scalar-tensor models). The RG flow of scalar theories is, in fact, easier to analyse.
For the asymptotic safety scenario (that is a conjecture of non-perturbative renormalizability of gravity) we will investigate the possibility of having limit cycles as UV completion of the RG flow. We will then study the asymptotic safety of a generic f(R) theory by quantizing a dynamically equivalent theory, i.e. a Brans-Dicke theory with
omega=0 in the local potential approximation.
For the Horava-Lifshitz gravity, that is a model in which perturbative renormalizability and unitarity are reconciled at the price of losing Lorentz invariance at the Planck Scale, we will evaluate the one-loop effective action for the projectable case in 2+1 dimensions, giving a first answer about the high energy behaviour of the theory.