Program on Wednesday, Nov. 10, 2021
topic: Carrollian symmetries and applications
13.30 - 14.10: Marc Henneaux (Université Libre de Bruxelles and International Solvay Institutes)
14.10 - 14.50: Stefan Vandoren (University of Utrecht)
14.50 - 15.00: short break
15.00 - 15.40: José Miguel Figueroa-O'Farrill (University of Edinburgh)
15.40 - 16.00: break
16.00 - 17.00 discussion moderated by Laura Donnay
TITLES + ABSTRACTS
Speaker: Marc Henneaux
Title: Carroll invariant field theories
Abstract: Conditions for a local field theory expressed in Hamiltonian form to be Carroll invariant are given. Electric and magnetic Carrollian limits of Lorentz-invariant theories are then defined and illustrated on various examples. The electric version of Carroll invariant gravity is also discussed and connected with the Belinski-Lifshitz-Khalatnikov (BKL) behaviour of the gravitational field near a spacelike singularity.
Based on M. Henneaux and P. Salgado-Rebolledo, arXiv:2109.06708 [hep-th].
Speaker: Stefan Vandoren
Title: Carroll symmetry, dark energy and inflation
Abstract: We determine the constraints on the energy-momentum tensor implied by Carroll symmetry and show that for energy-momentum tensors of perfect fluid form, these imply an equation of state E+P=0 for energy density plus pressure. Therefore Carroll symmetry might be relevant for dark energy and inflation. In the Carroll limit, the Hubble radius goes to zero and outside it recessional velocities are naturally large compared to the speed of light. The de Sitter group of isometries, after the limit, becomes the conformal group in Euclidean flat space. We also study the Carroll limit of chaotic inflation, and show that the scalar field is naturally driven to have an equation of state with w=-1. Finally we show that the freeze-out of scalar perturbations in the two point function at horizon crossing is a consequence of Carroll symmetry.
Speaker: José Miguel Figueroa-O'Farrill
Title: Poincaré-invariant Carroll-like structures at infinity
Abstract: I will report on a recent work with Emil Have, Stefan Prohazka and Jakob Salzer in which we study Poincaré-invariant homogeneous Carroll-like geometries at infinity in Minkowski spacetime. I will introduce several such geometries (some new, some old), describe them as homogeneous spaces of the Poincaré group and as grassmannians in Minkowski spacetime. Finally, in an embedding formalism, I will show how to reconstruct Minkowski spacetime from these asymptotic geometries.
