nLab mirror symmetry



Duality in string theory

String theory



To every complex 3-dimensional Calabi-Yau variety XX are associated two similar but differing types of sigma-model N=2N=2-supersymmetric 2d CFTs. There is at least for some CY XX a map XX^X \mapsto \hat X which exchanges the Hodge numbers h 1,1h^{1,1} and h 1,2h^{1,2} such that SCFT A(X)SCFT_A(X) is expected to be equivalent to SCFT B(X^)SCFT_B(\hat X).

SCFT A(X)SCFT B(X^). SCFT_A(X) \simeq SCFT_B(\hat X) \,.

This is called mirror symmetry. At least in some cases this can be understood as a special case of T-duality (Strominger-Yau-Zaslow 96).

In this form mirror symmetry remains a conjecture, not the least because for the moment there is no complete construction of these SCFTs. But to every such SCFT(X)SCFT(X) one can associate two TCFTs, A(X)A(X) and B(X)B(X), the A-model and the B-model. These N=1N=1 supersymmetric field theories were obtained by Edward Witten using a “topological twist”. The topological A-model can be expressed in terms of symplectic geometry of a variety and the topological B-model can be expressed in terms of the algebraic geometry of a variety.

These topological theories are easier to understand and do retain a little bit of the information encoded in the full SCFTs. In terms of these the statement of mirror symmetry says that passing to mirror CYs exchanges the A-model with the BB-model and conversely:

A(X)B(X^),B(X)A(X^). A(X) \simeq B(\hat X),\,\,\,\,\,\,\,B(X)\simeq A(\hat X) \,.

By a version of the cobordism hypothesis-theorem, these TCFTs (see there) are encoded by A-∞ categories that are Calabi-Yau categories: the A-model by the Fukaya category Fuk(X)Fuk(X) of XX which can be understood as a stable (∞,1)-category representing the Lagrangian intersection theory on the underlying symplectic manifold; and the B-model by an enhancement of the derived category of coherent sheaves D b(X^)D^b_\infty(\hat X) on X^\hat X.

In terms of this data, mirror symmetry is the assertion that these A-∞ categories are equivalent and simultaneously the same under exchange XX^X\leftrightarrow \hat{X}:

Fuk(X)D b(X^),andFuk(X^)D b(X). Fuk(X) \simeq D^b_\infty(\hat{X}), \,\,\,\, and \,\,\,\, Fuk(\hat{X}) \simeq D^b_\infty(X).

This categorical formulation was introduced by Maxim Kontsevich in 1994 under the name homological mirror symmetry. The equivalence of the categorical expression of mirror symmetry to the SCFT formulation has been proven by Maxim Kontsevich and independently by Kevin Costello, who showed how the datum of a topological conformal field theory is equivalent to the datum of a Calabi-Yau A-∞-category(see TCFT).

The mirror symmetry conjecture roughly claims that every Calabi-Yau 3-fold has a mirror. In fact one considers (mirror symmetry for) degenerating families for Calabi-Yau 3-folds in large volume limit (which may be expressed precisely via the Gromov-Hausdorff metric). The appropriate definition of (an appropriate version of) the Fukaya category of a symplectic manifold is difficult to achieve in desired generality. Invariants/tools of Fukaya category include symplectic Floer homology and Gromov-Witten invariants (building up the quantum cohomology).

Mirror symmetry is related to the T-duality on each fiber of an associated Lagrangian fibration Strominger-Yau-Zaslow 96.

Although the non-Calabi-Yau case may be of lesser interest to physics, one can still formulate some mirror symmetry statements for, for instance, Fano manifolds. The mirror to a Fano manifold is a Landau-Ginzburg model (see Hori-Vafa 00; see also work of Auroux for an explanation via the Strominger-Yau-Zaslow T-duality philosophy). Then the statements are: the A-model of the Fano (given by the Fukaya category) is equivalent to the B-model of the Landau-Ginzburg model (given by the category of matrix factorizations); and the B-model of the Fano (given by the derived category of sheaves) is equivalent to the A-model of the Landau-Ginzburg model (given by the Fukaya-Seidel category). A few of the relevant names: Kontsevich, Hori-Vafa, Auroux, Katzarkov, Orlov, Seidel, …


Relation to tropical geometry.

Close relation to tropical geometry, see e.g. Gross 11.



The original statement of the homological mirror symmetry conjecture is in

See also:



  • Maxim Kontsevich, On the History of quantum cohomology and homological mirror symmetry (2021) [video:YT]

Discussion amplifying the role of category theory, and higher geometry:

Further review:

The relation to T-duality was established in

Further references:

Discussion in the context of derived Morita equivalence includes

  • So Okada, Homological mirror symmetry of Fermat polynomials (arXiv:0910.2014)

Complete proofs

Here is a list with references that give complete proofs of homological mirror symmetry on certain (types of) spaces.

  • M. Abouzaid, I. Smith, Homological mirror symmetry for the four-torus, Duke Math. J. 152 (2010), 373–440, arXiv:0903.3065

  • A. Polishchuk and E. Zaslow, Categorical mirror symmetry: the elliptic curve, Adv. Theor. Math. Phys. 2:443470, 1998.

  • V. Golyshev, V. Lunts, D. Orlov, Mirror symmetry for abelian varieties, J. Alg. Geom. 10 (2001), no. 3, 433–496, math.AG/9812003

  • P. Seidel, Homological mirror symmetry for the quartic surface, arXiv:0310414

  • Alexander I. Efimov, Homological mirror symmetry for curves of higher genus, Inventiones Math. 166 (2006), 537–582, arXiv:0907.3903

  • D. Auroux, L. Katzarkov, D. Orlov, Mirror symmetry for Del Pezzo surfaces: Vanishing cycles and coherent sheaves, ; Mirror symmetry for weighted projective planes and their noncommutative deformations, Ann. Math. 167 (2008), 867–943, math.AG/0404281

  • Mohammed Abouzaid, Denis Auroux, Alexander I. Efimov, Ludmil Katzarkov, Dmitri Orlov, Homological mirror symmetry for punctured spheres, arxiv/1103.4322

  • Paul Seidel, Homological mirror symmetry for the genus two curve, J. Algebraic Geometry, to appear, arXiv:0812.1171

Computation via topological recursion

Computation via topological recursion in matrix models and all-genus proofs of mirror symmetry is due to

Last revised on April 1, 2024 at 09:01:48. See the history of this page for a list of all contributions to it.