# Is there stringy Morse theory?

This question is pretty vague and open. I'm just curious if anyone has considered this.

Morse theory has a nice physical formulation: a Morse function can be thought of as a potential, so the gradient flow is the force experienced by a particle. The equilibria are the critical points of the potential. If we take a supersymmetric extension of this as a quantum theory, its ground state structure computes the homology of the space the particle moves in.

What can strings moving in a manifold subject to a potential tell us about the topology of the manifold?

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You have to consider Picard-Lefschetz theory instead Morse theory and find what a stringy analog to $N=2$ SUSY QM is. An analog might be constructed from a new look at the path integral formulation of (complexified) $N=2$ SUSY QM (see Edward Witten's paper and Stephan Zheng's master thesis). You might also consider string topology.

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See Huijun Fan's paper as well. –  lav Nov 22 '12 at 15:05
Thanks for your answer! These look like some good references. –  Ryan Thorngren Nov 25 '12 at 5:50

Properties of Riemannian, Kähler and hyperKähler manifolds could be seen through dimensional reductions of source spaces (domains) of corresponding quantum SUSY non-linear sigma-models, models whose target spaces (codomains) are the above mentioned manifolds, e.g. you get $N=2$ SUSY QM i.e. quantum superparticle moving in a Riemannian manifold as a dimensional reduction of 2d $N=1+1$ quantum non-linear sigma-model over superMinkowski spacetime (1+1)|(1,1), a quantum non-linear sigma-model which is again a dimensional reduction of 3d $N=2$ quantum non-linear sigma model over superMinkowski spacetime (1+2)|2. $\mathbb{Z}$-grading of forms on a Riemannian manifold is the relic of $R$-symmetry i.e $SO(2)$-group of superPoincare group $P^{3|2}$.

Deformations of the above mentioned SUSY non-linear models are done via superpotentials which are expressed by corresponding real or holomorphic Morse functions.

http://arxiv.org/abs/hep-th/0311064

http://arxiv.org/abs/hep-th/0401175

http://arxiv.org/abs/hep-th/0407122

http://arxiv.org/abs/hep-th/0509163

and

http://arxiv.org/abs/hep-th/0702137

http://arxiv.org/abs/hep-th/0610149

http://arxiv.org/abs/0803.3302

http://golem.ph.utexas.edu/~distler/blog/archives/001030.html

http://golem.ph.utexas.edu/category/2012/07/notes_from_stringmath_2012.html

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I've merged your accounts again, which means that you can edit your two answer together. I really would like to encourage you to register: unregistered accounts are browser based and will lose contact from time to time. –  dmckee Nov 26 '12 at 20:10
For others' references : physics.stackexchange.com/review/suggested-edits/6545 I agree that the edit was justly rejected, but it may be that the suggester was the OP himself . The link added was: link.springer.com/article/10.1007%2Fs10773-010-0586-9 –  Dimensio1n0 Aug 22 '13 at 12:10