D-Branes and Quotient Singularities of Calabi-Yau Fourfolds
Kenji Mohri
TL;DR
This work examines a type IIB D1-brane at a Calabi–Yau fourfold orbifold, showing that worldvolume gauge anomalies are canceled by couplings to bulk RR chiral bosons and NSNS moduli. It develops a (0,2) gauged linear sigma model framework for the D1-brane and uses toric geometry to analyze the Higgs moduli space M_r, proving that for generic FI parameters M_r is a smooth fourfold birational to X_Γ but not necessarily Calabi–Yau. Calabi–Yau structure of M_r is tied to the existence of crepant resolutions of the orbifold; when such resolutions exist (class A), M_r can be Calabi–Yau, while for terminal or partially resolvable cases (classes B and C), M_r is typically non-CY. The results illuminate how bulk-brane couplings influence anomaly cancellation and moduli space geometry in two-dimensional (0,2) theories arising from D-branes at CY4 singularities, with implications for IR dynamics and the role of toric methods in D-brane gauge theories.
Abstract
We investigate a (0,2) gauge theory realized on the world volume of the type IIB D1-brane at the singular point of a Calabi-Yau fourfold. It is argued that the gauge anomaly can be canceled via coupling to the R-R chiral bosons in bulk IIB string. We find that for a generic choice of the Fayet-Iliopoulos parameters on the world volume, the Higgs moduli space is a smooth fourfold birational to the original Calabi-Yau fourfold, but is not necessarily a Calabi-Yau manifold.
