$q$-Stability conditions via $q$-quadratic differentials for Calabi-Yau-$\mathbb{X}$ categories

Abstract

Categorically, we introduce the Calabi-Yau-$\mathbb{X}$ categories $\mathcal{D}_{\mathbb{X}}$ of a graded marked surface $\mathbf{S}^λ$, as a $q$-deformation of the topological Fukaya category $\mathcal{D}_\infty$ of $\mathbf{S}^λ$. We show that $\mathcal{D}_\infty$ can be identified with the cluster-$\mathbb{X}$ category associated to $\mathcal{D}_{\mathbb{X}}$. Geometrically, we construct and identify the space of $q$-quadratic differentials on the logarithm surface $\operatorname{log}_{\mathbf{c}} \mathbf{S}_\vartriangle^λ$ with the space of induced $q$-stability conditions on $\mathcal{D}_{\mathbb{X}}$, for a complex parameter $s$ satisfying $\operatorname{Re}(s)\gg1$. When $s=N$ is an integer, the result gives an $N$-analogue of Bridgeland-Smith's result for realizing stability conditions on the orbit Calabi-Yau-$N$ category $\mathcal{D}_{\mathbb{X}}\mathbin{/\mkern-6mu/}[\mathbb{X}-N]$ via CY-$N$ type quadratic differentials. When the genus of $\mathbf{S}$ is zero, the space of $q$-quadratic differentials can be also identified with framed Hurwitz spaces. As a byproduct, the result confirms the conjectural almost Frobenius structure on spaces of $q$-stability conditions for type $A$.