Gauge origami and quiver W-algebras III: Donaldson--Thomas $qq$-characters
Taro Kimura, Go Noshita
TL;DR
This work advances the BPS/CFT dictionary by introducing Donaldson--Thomas $qq$-characters as operator lifts of equivariant DT vertices and develops a comprehensive free-field realization framework for D4, D6, and D8 brane configurations with nontrivial boundary data. It constructs DT$qq$-characters across D4, D6, and D8 sectors, including legs, surfaces, and hypersurfaces, and provides explicit contour-integral and vertex-operator realizations that reproduce DT and magnificent four partition functions. A central achievement is the demonstration of commutativity and sign rules for D6 and D8 $qq$-characters, justified via infinite-product fusion and supported by low-instanton checks and plethystic interpretations, which underpins a consistent BPS/CFT correspondence. The results pave the way toward webs or 4G networks of BPS $qq$-characters, enabling gluing rules for toric Calabi--Yau 4-folds and connecting to DT/PT-type counts, with future work aimed at PT $qq$-characters and a full edge/face gluing formalism.
Abstract
We further develop the BPS/CFT correspondence between quiver W-algebras/$qq$-characters and partition functions of gauge origami. We introduce $qq$-characters associated with multi-dimensional partitions with nontrivial boundary conditions which we call Donaldson--Thomas (DT) $qq$-characters. They are operator versions of the equivariant DT vertices of toric Calabi--Yau three and four-folds. Moreover, we revisit the construction of the D8 $qq$-characters with no boundary conditions and give a quantum algebraic derivation of the sign rules of the magnificent four partition function. We also show that under the proper sign rules, the D6 and D8 $qq$-characters with no boundary conditions all commute with each other and discuss its physical interpretation.
