On cohomological and K-theoretical Hall algebras of symmetric quivers

Abstract: We give a brief review of the cohomological Hall algebra CoHA $\mathcal{H}$ and the K-theoretical Hall algebra KHA $\mathcal{R}$ associated to quivers. In the case of symmetric quivers, we show that there exists a homomorphism of algebras (obtained from a Chern character map) $\mathcal{R}\to \hat{\mathcal{H}}^{\sigma}$ where $\hat{\mathcal{H}}^{\sigma}$ is a Zhang twist of the completion of $\mathcal{H}$. Moreover, we establish the equivalence of categories of ``locally finite'' graded modules $\hat{\mathcal{H}}^{\sigma}-{\rm Mod}{lf}\simeq \mathcal{R}{\mathbb Q}-{\rm Mod}{lf}$. Examples of locally finite $\hat{\mathcal{H}}^{\sigma}$-, resp. $\mathcal{R}{\mathbb Q}$- modules appear naturally as the cohomology, resp. K-theory, of framed moduli spaces of quivers.