Abstract:
In this talk, we first derive the CR version of Lichnerowicz formula. Secondly, by applying the CR Lichnerowicz formula, we are able to obtain a parallel result of the eigenvalue estimate for the Dirac operator in Riemannian geometry. That is, in a three-dimensional closed pseudohermitian manifold with vanishing pseudohermitian torsion, any eigenvalue of the Dirac operator has a uniform lower bound.