Zoom link: Please email Silvia Nagy (s.nagyATqmul.ac.uk) or Jungwook Kim (jung-wook.kimATqmul.ac.uk) for the zoom link. Abstract:In string theory SL(2,Z) invariant functions, such as modular graph functions or coefficient functions of higher derivative corrections, are ubiquitous. Using a representation in terms of Poincaré series we can combine different methods for asymptotic expansions and obtain the complete perturbative and non-perturbative expansion. In the case of the higher derivative corrections, these terms have an interpretation in terms of perturbative string loop effects and pairs of instantons/anti-instantons. There will also be a pre-seminar for the students which will begin at 2:30 pm.