Joint hep-th seminars with ULB, VUB, KUL and UGent

On the 24th of April UMONS will host the Belgian joint theoretical high-energy physics seminars organised by the Service de Physique de l’Univers, Champs et Gravitation of UMONS, the Service de Physique Théorique and the Service de Physique Théorique et Mathématique, both of the ULB, the Theoretical Particle Physics Group of the VUB, the High Energy Physics and Relativistic Field Theory group of the KUL, the Theoretical High Energy Physics group of the UGent and the International Solvay Institutes.

The speakers will be Sylvain Lavau (Ruđer Bošković Institute), Tim Adamo (Edinburgh University) and Victor Godet (SISSA Trieste):

11h00, room Vésale 30, building Vésale: Sylvain Lavau

A graded geometric perspective on tensor hierarchies

Tensor hierarchies, as they emerge in gauged supergravity, are differential graded Lie algebras with specific properties. This implies that the space of differential forms taking values in a tensor hierarchy algebra (THA) is also a differential graded Lie algebra L, of which the embedding tensor is a Maurer-Cartan element. Whenever one makes a gauge transformation of the latter, one obtains a homological derivation on the space of forms valued in the THA. In the graded geometric language, this makes L a differential graded Lie algebroid. All relevant physical objects — the gauge fields, the field strengths, the gauge transformations and their commutator — then inherit a very simple graded geometric interpretation. This opens the possibility of unifying many gauge theories (Yang-Mills, Leibniz,…) under one unique formalism. Moreover, the L_infinity algebras associated to such theories are readily obtained from the differential graded Lie algebra by a very simple procedure. The talk will be an overview of some mathematical properties of tensor hierarchy algebras, and of their graded geometric interpretation.

13h00, room Vésale 20, building Vésale: Tim Adamo

Scattering on self-dual black holes

Tree-level graviton scattering amplitudes provide an on-shell model for wave-wave scattering in general relativity, but computing them with traditional perturbative methods is hard due to the non-polynomial nature of the Einstein-Hilbert action. Over the years, many alternative approaches, which have nothing to do with standard Feynman rules, have enabled the computation of all-multiplicity formulae for graviton scattering in Minkowski spacetime. However, studying graviton scattering in non-perturbative curved spacetimes, like black holes, remains an extremely difficult problem. In this talk, I will discuss a simplification of this problem: graviton scattering on a self-dual black hole (in particular, a self-dual Taub-NUT space). This lets us bring powerful integrability methods to bear while still exhibiting the non-linear and non-perturbative hallmarks of ‘real world’ graviton scattering on black holes.

14h30, room Vésale 20, building Vésale: Victor Godet

Quantum cosmology as automorphic dynamics

I will discuss some recent progress on the Wheeler-DeWitt equation with positive cosmological constant. This suggests an equivalence between quantum cosmology in three dimensions and a driven particle on moduli space.