Speaker
Manuel Reichert
(University of Sussex)
Description
I will present the first direct and non-perturbative computation of the graviton spectral function in quantum gravity. This is achieved with the help of a novel Lorentzian renormalisation group approach, combined with a spectral representation of correlation functions. We find a positive graviton spectral function, showing a massless one-graviton peak and a multi-graviton continuum with an asymptotically safe scaling for large spectral values. There are no ghost or tachyonic instabilities, which is crucial for the unitarity of the theory. Our findings open a door to investigate scattering amplitudes and unitarity of fully quantised gravity.
