Abstract In this talk, we will be interested in the problem of scattering by strictly convex obstacles in 2D and we will give estimates for the number of resonances in regions $\{ \re \lambda \in [r, r+1], \im \lambda \geq - \gamma \}$ in the limit $r \to + \infty$. It is now well known in open quantum chaos that the dimension of the trapped set appears when counting resonances in such boxes : ...
Abstract:A famous theorem of Gromov states that if a finitely generated group G has polynomial growth (i.e. there is a polynomial p such that the ball of radius n in some Cayley graph of G always contains at most p(n) vertices) then G has a nilpotent subgroup of finite index. Breuillard, Green and Tao proved a finitary refinement of this theorem, stating that if *some* ball of radius n contain...