Contributor info: Dr Manuel Reichert

Alfio Bonanno, Tobias Denz, Jan M. Pawlowski, Manuel Reichert

SciPost Phys. 12, 001 (2022) · published 4 January 2022 | Toggle abstract · pdf

We reconstruct the Lorentzian graviton propagator in asymptotically safe quantum gravity from Euclidean data. The reconstruction is applied to both the dynamical fluctuation graviton and the background graviton propagator. We prove that the spectral function of the latter necessarily has negative parts similar to, and for the same reasons, as the gluon spectral function. In turn, the spectral function of the dynamical graviton is positive. We argue that the latter enters cross sections and other observables in asymptotically safe quantum gravity. Hence, its positivity may hint at the unitarity of asymptotically safe quantum gravity.

Astrid Eichhorn, Peter Labus, Jan M. Pawlowski, Manuel Reichert

SciPost Phys. 5, 031 (2018) · published 4 October 2018 | Toggle abstract · pdf

We investigate the asymptotic safety scenario for a scalar-gravity system. This system contains two avatars of the dynamical Newton coupling, a gravitational self-coupling and a scalar-graviton coupling. We uncover an effective universality for the dynamical Newton coupling on the quantum level: its momentum-dependent avatars are in remarkable quantitative agreement in the scaling regime of the UV fixed point. For the background Newton coupling, this effective universality is not present, but qualitative agreement remains.