Circle actions and mores theory on quaternion-kahler manifolds

摘要

In this paper we study quaternion-Kahler manifolds endowed with an isometric S~1-action. We consider the corresponding moment map #mu# and prove that the only compact quaternion-Kahler manifold with positive scalar curvature which admits an isometric circle action free on #mu#~(-1)(0) is the quaternionic projective space HP~n.