A non-displacable torus in T*S2

Leonid Polterovich exhibited a beautiful Lagrangian torus in T*S2 and asked whether this torus is Hamiltonianly displaceable. In joint work with Urs Frauenfelder we prove that its Lagrangian Floer homology does not vanish, indeed equals the singular homology of the torus. In particular, this gives a negative answer to Polterovich's question. In the talk I will describe the construction of the Lagrangian torus and present the computation of the Lagrangian Floer homology which is based on an symmetry argument.

This talk does not assume familiarity with all details of Floer homology. A basic exposure to the ideas of Floer theory is sufficient.