Topological sigma models in four-dimensions and triholomorphic maps
Jun, 199347 pages
Published in:
- Nucl.Phys.B 416 (1994) 255-300
e-Print:
- hep-th/9306080 [hep-th]
Report number:
- SISSA-73-93-EP
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Abstract:
It is well-known that topological sigma-models in 2 dimensions constitute a path-integral approach to the study of holomorphic maps from a Riemann surface S to an almost complex manifold K, the most interesting case being that where K is a Kahler manifold. We show that, in the same way, topological sigma-models in 4 dimensions introduce a path integral approach to the study of triholomorphic maps q:M-->N from a 4dimensional Riemannian manifold M to an almost quaternionic manifold N. The most interesting cases are those where M, N are hyperKahler or quaternionic Kahler. BRST-cohomology translates into intersection theory in the moduli-space of this new class of instantonic maps, named by us hyperinstantons. The definition of triholomorphicity that we propose is expressed by the equation q_*-J_u q_* j_u = 0, u=1,2,3, where {j_u} is an almost quaternionic structure on M and {J_u} is an almost quaternionic structure on N. This is a generalization of the Cauchy-Fueter equations. For M, N hyperKahler, this generalization naturally arises by obtaining the topological sigma-model as a twisted version of the N=2 globally supersymmetric sigma-model. We discuss various examples of hyperinstantons, in particular on the torus and the K3 surface. We also analyse the coupling of the topological sigma-model to topological gravity. The study of- sigma model: nonlinear
- dimension: 2
- field theory: topological
- path integral
- Riemann surface
- field theory: Kaehler
- coset space: quaternion
- algebra: Becchi-Rouet-Stora
- cohomology
- differential forms
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