|
We use the equivalence between embedded contact homology and Seiberg–Witten
Floer homology to obtain the following improvements on the Weinstein conjecture.
Let Y be a closed oriented connected 3–manifold with a stable Hamiltonian
structure, and let R denote the associated Reeb vector field on Y . We prove that if Y
is not a T2–bundle over S1, then R has a closed orbit. Along the way we prove
that if Y is a closed oriented connected 3–manifold with a contact form
such that all Reeb orbits are nondegenerate and elliptic, then Y is a lens
space. Related arguments show that if Y is a closed oriented 3–manifold
with a contact form such that all Reeb orbits are nondegenerate, and if Y is
not a lens space, then there exist at least three distinct embedded Reeb
orbits.
|