We will show that the cotangent bundle of a manifold whose free loopspace
homology grows exponentially is not symplectomorphic to any smooth affine
variety. We will also show that the unit cotangent bundle of such a manifold is
not Stein fillable by a Stein domain whose completion is symplectomorphic to a
smooth affine variety. For instance, these results hold for end connect sums of
simply connected manifolds whose cohomology with coefficients in some field has
at least two generators. We use an invariant called the growth rate of
symplectic homology to prove this result.Comment: 79 pages, 3 figures. Corrected mistakes and changed the introductio