Speaker
Description
We study the interplay of scalar matter with quantum gravity in the Lorentzian signature using the recently developed spectral fRG. The spectral fRG is based on the Callan-Symanzik cutoff, which acts as a scale-dependent mass and preserves the Källén-Lehmann spectral representation, in combination with dimensional regularisation. In this setup, we compute the impact of N_S minimally coupled scalars on the gravitational UV fixed point and on the transverse-traceless graviton spectral function. Scalar matter increases the strength of the fixed-point Newton coupling, and beyond N_S = 21, the fixed point is lost. A similar behaviour was found in previous Euclidean studies. Remarkably, scalar matter provides a strictly positive and gauge-independent contribution to the graviton spectral function, leaving the property of positivity intact.
| Affiliation | Univeristy of Sussex |
|---|---|
| Career status | Student |