Speaker
Description
Divergences in perturbative expansions often signal the
presence of rich physics. Perturbations around curved spacetime can be
systematically handled using the (J)WKB series. However, while being
asymptotic expansions, these series are typically divergent. Recent
developments have demonstrated that exact WKB analysis, combined with
Borel resummation, provides a powerful framework to go beyond the
limitations of perturbation theory and to access the global structure of
exact solutions. This approach unveils nonperturbative effects that
cannot be captured by standard expansions and thus offers deeper
insights into the dynamics in curved spacetime. In this talk, I will
focus on black hole perturbations as a particularly illuminating
application and discuss how exact WKB techniques clarify the role of
singularities, providing a novel analytical technique to compute
quasi-normal modes (QNMs).
