Deformations of Noncompact Calabi-Yau threefolds

Abstract

We describe deformations of the noncompact Calabi-Yau threefolds $W_k = \mbox{Tot}(\mathcal{O}_{\mathbb{P}^1}(-k) \oplus \mathcal{O}_{\mathbb{P}^1}(k-2))$ for $k=1,2,3$, as well as their moduli of holomorphic vector bundles of rank $2$. Deformations are computed concretely by calculations of $H^1(W_k,T{W}_k)$. Information about the moduli of vector bundles is obtained by analysing bundles that are extensions of line bundles. We show that for each $k=1,2,3$ the associated structures are qualitatively different, and we also comment on their difference from the analogous structures for the simpler noncompact twofolds $\mbox{Tot}(\mathcal{O}_{\mathbb{P}^1}(-k))$ which had been studied previously by the authors. We describe deformations of the noncompact Calabi-Yau threefolds $W_k=\text{Tot}({\mathcal{O}}_{{\mathbb{P}}^1}(-k)\oplus {\mathcal{O}}_{{\mathbb{P}}^1}(k-2))$ for $k=1,2,3$. We compute deformations concretely by calculations of ${\text{H}}^1(W_k,T{W}_k)$ via Čech cohomology. We show that for each $k=1,2,3$ the associated structures are qualitatively different, and we also comment on their difference from the analogous structures of simpler noncompact twofolds $\text{Tot}({\mathcal{O}}_{{\mathbb{P}}^1}(-k))$.