Lorentzian quantum gravity and the graviton spectral function

Understand

We 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.
• We also study the impact of a cosmological constant.