Subclasses of meromorphically multivalent functions defined by a differential operator

In this paper we introduce and study two new subclasses Σλμmp(α,β)Σλμmp(α,β) and Σλμmp+(α,β) of meromorphically multivalent functions which are defined by means of a new differential operator. Some results connected to subordination properties, coefficient estimates, convolution properties, integral representation and distortion theorems are obtained. We also extend the familiar concept of (n,δ)(n,δ)-neighborhoods of analytic functions to these subclasses of meromorphically multivalent functions.