Quantum Gravity Seminar: Manuel Reichert

Speaker: Manuel Reichert (U. Sussex)

Spacetime coordinates: Wed @ 13:30, Auditorium A

Zoom Link: https://ucph-ku.zoom.us/j/9295289933?omn=67282578176

Title: Towards Scattering Amplitudes in Asymptotically Safe Quantum Gravity

Abstract: The asymptotic safety program provides a promising framework for a consistent quantum theory of gravity. It rests only on diffeomorphism invariance and the assumption that the spacetime metric encodes the fundamental degrees of freedom. Ultraviolet completeness is achieved through the presence of an interacting renormalisation-group fixed point, which ensures finiteness at arbitrarily high energies. Until recently, most investigations of asymptotically safe gravity were restricted to Euclidean-signature formulations. In this talk, I will present recent progress toward the non-perturbative computation of graviton correlation functions on Lorentzian-signature backgrounds, including the calculation of a Källén–Lehmann spectral representation for the graviton propagator. These correlation functions are obtained both from direct Lorentzian calculations and via analytic reconstruction from Euclidean data. The resulting framework enables tests of quantum gravity on physically relevant backgrounds, allows for the computation of scattering amplitudes, and provides new insights into the unitarity properties of asymptotically safe gravity.