paper

Cohomological Hall algebra of a symmetric quiver

arXiv:1103.2736 · doi:10.1112/S0010437X12000152

Abstract

In the paper \cite{KS}, Kontsevich and Soibelman in particular associate to each finite quiver with a set of vertices the so-called Cohomological Hall algebra $\cH,$ which is -graded. Its graded component $\cH_γ$ is defined as cohomology of Artin moduli stack of representations with dimension vector The product comes from natural correspondences which parameterize extensions of representations. In the case of symmetric quiver, one can refine the grading to and modify the product by a sign to get a super-commutative algebra $(\cH,\star)$ (with parity induced by -grading). It is conjectured in \cite{KS} that in this case the algebra $(\cH\otimes\Q,\star)$ is free super-commutative generated by a -graded vector space of the form $V=V^{prim}\otimes\Q[x],$ where is a variable of bidegree and all the spaces are finite-dimensional. In this paper we prove this conjecture (Theorem 1.1). We also prove some explicit bounds on pairs for which (Theorem 1.2). Passing to generating functions, we obtain the positivity result for quantum Donaldson-Thomas invariants, which was used by S. Mozgovoy to prove Kac's conjecture for quivers with sufficiently many loops \cite{M}. Finally, we mention a connection with the paper of Reineke \cite{R}.

16 pages, no figures; a reference added

Cited by in corpus (38)