Cohomological integrality for 2-Calabi-Yau categories

In this talk, I will explain how one can decompose the cohomology of moduli stacks of objects for a large class of 2-Calabi-Yau categories. Our main tools are cohomological Hall algebras and their associated BPS algebras (in their associative and Lie algebra versions). Important examples are given by representations of preprojective algebras of quivers and finite length sheaves on surfaces. In the latter case, we can recover the generating series of Betti numbers of the moduli stack in an efficient way.