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Quantum cohomology of blowups

Hiroshi Iritani

Abstract

We prove a decomposition theorem of the quantum cohomology D-module of the blowup of a smooth projective variety X along a smooth subvariety Z. The main tools we use are shift operators and Fourier analysis for equivariant quantum cohomology.

Quantum cohomology of blowups

Abstract

We prove a decomposition theorem of the quantum cohomology D-module of the blowup of a smooth projective variety X along a smooth subvariety Z. The main tools we use are shift operators and Fourier analysis for equivariant quantum cohomology.
Paper Structure (49 sections, 38 theorems, 254 equations, 5 figures, 1 table)

This paper contains 49 sections, 38 theorems, 254 equations, 5 figures, 1 table.

Key Result

Theorem 1.1

There exist a formal invertible change of variables $H^*({\widetilde{X}}) \to H^*(X) \oplus H^*(Z)^{\oplus (r-1)}$, ${\tilde{\tau}} \mapsto \left(\tau({\tilde{\tau}}), \{\varsigma_j({\tilde{\tau}})\}_{0\le j\le r-2}\right)$ defined over $\mathbb{C}(\!(\mathfrak{q}^{-\frac{1}{r-1}})\!)[\![Q]\!]$ and that commutes with the quantum connection. Moreover, $\Psi$ intertwines the pairing $P_{\widetilde{

Figures (5)

  • Figure 1: The GIT fan on the $T$-ample cone $C_T(W)$ and the associated "toric variety" $\mathfrak{M} = \mathfrak{M}_X \cup \mathfrak{M}_{{\widetilde{X}}}$. See also Figure \ref{['fig:Mori_cones']}. The variable $\mathfrak{q}$, which is written also as $y S^{-1}$ in the main body of the text, comes from a shift operator.
  • Figure 2: $W = \operatorname{Bl}_{Z\times \{0\}} (X\times \mathbb{P}^1)$ and a moment map $\mu \colon W\to \mathbb{R}$
  • Figure 3: A schematic picture of the cones $C_X^\vee$ and $C_{\widetilde{X}}^\vee$ in $N_1^T(W)$.
  • Figure 4: Integration contour on the $\lambda$-plane
  • Figure 5: Euler eigenvalues near $Q={\tilde{\tau}}=0$ for $r=4$. The eigenvalues of $E_Z\star_{\varsigma_j({\tilde{\tau}})}$, $j=0,\dots,r-2$ surround those of $E_X\star_{\tau({\tilde{\tau}})}$ as "satellites". Here we assume the convergence of quantum cohomology and the maps $\tau({\tilde{\tau}}), \varsigma_j({\tilde{\tau}})$. We also choose $\mathfrak{q}$ to be positive real.

Theorems & Definitions (97)

  • Theorem 1.1: see Theorem \ref{['thm:decomposition_fd']} for the details
  • Corollary 1.2
  • Remark 1.3
  • Remark 1.4
  • Remark 1.5
  • Remark 1.6
  • Remark 1.7: related works
  • Conjecture 1.8
  • Remark 1.9
  • Remark 1.10
  • ...and 87 more