Quantum gravity phenomenology from the perspective of quantum general relativity and quadratic gravity

Multi-messenger astronomy provides us with the possibility of discovering phenomenological signatures of quantum-gravity effects. This should be of paramount importance in the pursuit of an elusive quantum theory for the gravitational interactions. Here we discuss feasible explorations within the effective field theory (EFT) treatment of general relativity. By exploring current techniques borrowed from modern amplitude methods, we calculate leading quantum corrections to the classical radiated momentum and spectral waveforms. The lessons drawn from these low-energy results are that phenomenological applications in gravitational-wave physics can be discussed in line with the EFT approach. In turn, we also examine possible phenomenological surveys from the perspective of a UV completion for quantum gravity which employs the metric as the fundamental dynamical variable, namely quadratic gravity. Being more specific, by resorting to the eikonal approximation, we compute the leading-order time delay/advance in the scattering of light by a heavy object and find a possible significant deviation from the standard general-relativity prediction. This allows us to probe causal uncertainty due to quantum fluctuations of the gravitational field as a genuine prediction from Planck-scale physics.

Automated summary

Multi-messenger astronomy provides us with the possibility of discovering phenomenological signatures of quantum-gravity effects. Feasible explorations within the effective field theory (EFT) treatment of general relativity have been discussed. Current techniques borrowed from modern amplitude methods were used to calculate leading quantum corrections to the classical radiated momentum and spectral waveforms. The results highlight the potential applications of the EFT approach in gravitational-wave physics. Furthermore, possible phenomenological surveys from the perspective of a UV completion for quantum gravity employing quadratic gravity were examined, revealing a deviation from the standard general-relativity prediction.