Psi-class intersections on Hassett spaces for genus 0 with all weights $\frac {1}{2}$

Abstract

Hassett spaces are moduli spaces of weighted stable pointed curves. We consider such spaces of curves of genus $0$ with weights all $\frac {1}{2}$. These spaces are interesting, since they are isomorphic to $\overline{M}_{0,n}$ but have different universal families and different intersection theory. We develop a closed formula for intersections of $\psi $-classes on such spaces. In our main result, we encode the formula for top intersections in a generating function obtained by applying a differential operator to the Witten potential.