Richard Thomas: Nonabelian DT theory from abelian DT theory
Time: Tue 2021-09-07 14.30 - 15.30
Lecturer: Richard Thomas (Imperial College London, online)
Abstract: Fix a Calabi–Yau 3-fold X. Its DT invariants count stable bundles and sheaves on X. Joyce's generalised DT invariants count semistable bundles and sheaves on X. I will describe work with Soheyla Feyzbakhsh showing these generalised DT invariants in any rank r can be written in terms of rank 1 invariants. By the MNOP conjecture the latter are determined by the GW invariants of X. Along the way we also express rank r DT invariants in terms of rank 0 invariants counting sheaves supported on surfaces in X. These invariants are predicted by S-duality to be governed by (vector-valued mock) modular forms.