Quantum Gravity Seminar: Johanna Borissova

Speaker: Johanna Borissova (Imperial College London)

Spacetime coordinates: Wed @ 14:30, Auditorium A

Zoom Link: https://ucph-ku.zoom.us/j/9295289933?omn=67282578176

Title: Area-metric gravity as an effective field theory

Abstract: Area metrics are higher-rank tensors which provide a candidate parametrization for the extended gravitational configuration space of loop quantum gravity and spin foams in the semiclassical regime. In this talk, I will present a bottom-up construction of generally covariant area-metric gravity to quadratic order in fluctuations and derivatives. Subsequently, I will describe how the Plebanski formulation of gravity can be applied to derive non-linear area-metric theories in which the Barbero-Immirzi parameter enters as an interaction coupling. The resulting local effective actions provide a playgound for the analysis of renormalization-group flows. Specifically, I will discuss the decoupling of the non-length-metric degrees of freedom of the area metric at low energies, and demonstrate why parity invariance of the low-energy theory cannot be emergent symmetry. Finally, I will consider quasi-local Einstein-Weyl gravity as an effective theory for the length-metric degrees of freedom of the area metric. Focusing on static spherically symmetric spacetimes, I will discuss solutions in the weak-field regime and present a complete classification of Frobenius solutions around generic expansion points.