Attractor invariants, brane tilings and crystals

TL;DR

This paper explores attractor invariants in the context of D-brane bound states on Calabi-Yau threefolds, providing explicit computations for toric cases and linking them to crystal counting and quiver representations.

Contribution

It introduces explicit calculations of attractor invariants for toric Calabi-Yau threefolds, connecting them to quiver representations and crystal models, and predicts their values across stability chambers.

Findings

Attractor invariants vanish unless related to simple representations or kernel of Euler form.

Explicit formulas for attractor invariants in specific toric Calabi-Yau cases.

Agreement between non-commutative refined DT invariants and molten crystal counting.

Abstract

Supersymmetric D-brane bound states on a Calabi-Yau threefold $X$ are counted by generalized Donaldsdon-Thomas invariants $\Omega_Z(\gamma)$, depending on a Chern character (or electromagnetic charge) $\gamma\in H^*(X)$ and a stability condition (or central charge) $Z$. Attractor invariants $\Omega_*(\gamma)$ are special instances of DT invariants, where $Z$ is the attractor stability condition $Z_\gamma$ (a generic perturbation of self-stability), from which DT invariants for any other stability condition can be deduced. While difficult to compute in general, these invariants become tractable when $X$ is a crepant resolution of a singular toric Calabi-Yau threefold associated to a brane tiling, and hence to a quiver with potential. We survey some known results and conjectures about framed and unframed refined DT invariants in this context, and compute attractor invariants explicitly for a variety of toric Calabi-Yau threefolds, in particular when $X$ is the total space of the canonical bundle of a smooth projective surface, or when $X$ is a crepant resolution of $C^3/G$. We check that in all these cases, $\Omega_*(\gamma)=0$ unless $\gamma$ is the dimension vector of a simple representation or belongs to the kernel of the skew-symmetrized Euler form. Based on computations in small dimensions, we predict the values of all attractor invariants, thus potentially solving the problem of counting DT invariants of these threefolds in all stability chambers. We also compute the non-commutative refined DT invariants and verify that they agree with the counting of molten crystals in the unrefined limit.