Self-consistent graviton spectral function in Lorentzian quantum gravity

Abstract:

We present the first fully self-consistent computation of the graviton spectral function in quantum gravity, using the spectral renormalisation group for gravity put forward in arXiv:2111.13232v2 [hep-th] within a physical mass-shell renormalisation scheme. Here, self-consistency refers to the fact that the full non-perturbative spectral function is used in the diagrams, including the scattering continuum. We find a positive graviton spectral function with a massless one-graviton peak and a multi-graviton continuum with a close-to-quadratic spectral decay in the ultraviolet. Within the physical on-shell renormalisation scheme, the graviton satisfies the sum rule of an asymptotic state and features a unit total spectral weight. We briefly discuss the implications of the physical formulation for the computation of scattering processes and investigations of unitarity in asymptotically safe quantum gravity.

J. M. Pawlowski, M. Reichert, J. Wessely, „Self-consistent graviton spectral function in Lorentzian
quantum gravity“, 29. Juli 2025, arXiv:2507.22169 (2025).

https://arxiv.org/abs/2507.22169

Related to Project A02, B03