Thibaut Grouy | Searcharxiv

arXiv2018

Orbital integrals on Lorentzian symmetric spaces

In this paper, we address the problem of determining a function in terms of its orbital integrals on Lorentzian symmetric spaces. It has been solved by S. Helgason for even-dimensional isotropic Lorentzian symmetric spaces via a limit formula involving the Laplace-Beltrami operator. The result has been extended by J. Orloff for rank-one semisimple pseudo-Riemannian symmetric spaces giving the keys to treat the odd-dimensional isotropic Lorentzian symmetric spaces. Indecomposable Lorentzian symmetric spaces are either isotropic or have solvable transvection group. We study orbital integrals including an inversion formula on the solvable ones which have been explicitly described by M. Cahen and N. Wallach.

math.DG↗

arXiv2016

A possible symplectic framework for Radon-type transforms

Our project is to define Radon-type transforms in symplectic geometry. The chosen framework consists of symplectic symmetric spaces whose canonical connection is of Ricci-type. They can be considered as symplectic analogues of the spaces of constant holomorphic curvature in Kählerian Geometry. They are characterized amongst a class of symplectic manifolds by the existence of many totally geodesic symplectic submanifolds. We present a particular class of Radon type tranforms, associating to a smooth compactly supported function on a homogeneous manifold $M$, a function on a homogeneous space $N$ of totally geodesic submanifolds of $M$, and vice versa. We describe some spaces $M$ and $N$ in such Radon-type duality with $M$ a model of symplectic symmetric space with Ricci-type canonical connection and $N$ an orbit of totally geodesic symplectic submanifolds.

math.SG↗