Rafael Robson Lino dos Santos: The weak-gravity bound and the need for spin in asymptotically safe matter-gravity models

In this talk, we introduce the weak-gravity bound for scalar-gravity systems within the asymptotic-safety paradigm. The weak-gravity bound arises when gravitational fluctuations exceed a critical strength. Beyond this critical strength, gravitational fluctuations can generate complex fixed-point values in higher-order scalar interactions. Asymptotic safety can thus only be realized at sufficiently weak gravitational interactions. We find that within truncations of the matter-gravity dynamics, the fixed-point for the gravitational parameters lies beyond the critical strength unless we include spinning matter in the model.