Form Factors in Quantum Gravity - contrasting non-local, ghost-free\n gravity and Asymptotic Safety

Abstract

Form factors constitute the key building block when organising the\ngravitational dynamics in terms of a curvature expansion. They generalise the\nconcept of momentum-dependent couplings to curved spacetime. Moreover, they may\ncapture modifications of the gravitational interactions at high energy scales\nin a non-perturbative way. We briefly review the role of form factors in\nvarious quantum gravity programmes with special emphasis on non-local,\nghost-free gravity and asymptotically safe gravity. In this context, we\nintroduce a quantum gravity motivated scalar toy model, which demonstrates that\nLorentzian asymptotic safety may be compatible with the causal propagation of\ngravitons.\n