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WS26/27 – Abstract
Manuel Reichert
(University of Sussex)
29.10.2026
The Asymptotically Safe Standard Model: NLO Critical Exponents and Graviton-Mediated Scattering
Asymptotic safety is a promising framework for a consistent quantum theory of gravity. It is built on diffeomorphism invariance and on the metric as the carrier of the fundamental degrees of freedom, and it achieves ultraviolet completion through quantum scale invariance at an interacting fixed point. Among the open key questions are the precise determination of the infrared landscape that can be reached from this fixed point and the unitarity of the theory. In this talk, I report recent progress on both. First, I present a next-to-leading-order computation of critical exponents, which are crucial inputs for determining the landscape. The result shows that Yukawa interactions are compatible with asymptotic safety, evading no-go results for the Standard Model coupled to gravity. Second, I present non-perturbative computations carried out directly in Lorentzian signature, based on spectral representations of correlation functions. These give direct access to unitarity and causality, which I illustrate with a healthy Källén–Lehmann representation of the graviton propagator and with graviton-mediated scattering amplitudes that satisfy unitarity bounds.
