On Zero Energy States in SUSY Quantum Mechanics on Manifolds

We study the zero modes of the operator $H_f=D^*_fD_f$, with a Dirac type operator $D_f$, acting on the spinor bundle over a closed even dimensional Riemannian manifold $M$. The operator $D_f=D+ifI$ is a deformation of the Dirac operator $D$ by a smooth function $f$. We obtain sufficient conditions on the deformation function that guarantee the positivity of the operator $H_f$, that is, the absence of zero modes. We also show that these conditions are not necessary and provide an explicit counterexample of a zero mode of the operator $H_f$.