Institute for Mathematics, Astrophysics and Particle Physics
I follow an open science policy. All my publications are available through inspire.
The renormalization group flow of the Einstein-Hilbert action supplemented by the two-loop counterterm found by Goroff and Sagnotti exhibits the non-Gaussian fixed point crucial for Asymptotic Safety. The new operator corresponds to an irrelevant direction and does not introduce a undetermined coupling constant.
We lay the ground work for studying renormalization group flows of gravity in the ADM-formalism. It is shown that Asymptotic Safety also holds when the beta functions obtained within the Einstein-Hilbert projection are continued to Lorentzian signature. The techniques developed are also suitable for computing renormalization group flows within Horava-Lifshitz gravity.
This is the first time that a non-perturbative computation based on the gravitational effective average action disentangles the running coupling constants associated with the square of the Ricci-scalar and the square of the Riemann tensor. The separation of tensor structures has profound consequences for the stability coefficients associated with Asymptotic Safety: instead of a pair of complex coefficients seen in the Einstein-Hilbert case, the computation exhibits 4 real critical exponents. Only three coefficients turn out to encode relevant coupling constants, providing strong evidence for the predictiveness of Asymptotic Safety.
We determine the hypermultiplet moduli space of Type IIB string theory compactified on a generic Calabi-Yau threefold including all perturbative string corrections and a wide class of non-perturbative corrections originating from D(-1) and D1-brane instanton contributions.
The work constructs the phase diagram of Quantum Einstein Gravity in the Einstein-Hilbert approximation. In particular, it is shown that the non-Gaussian fixed point, being at the heart of the Asymptotic Safety program, is connected to a classical regime by continuous renormalization group trajectories.