Subclasses of meromorphically multivalent functions defined by a differential operator

In this paper we introduce and study two new subclasses Σλμmp(α, β) and Σ+ λμmp(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)-neighborhoods of analytic functions to these subclasses of meromorphically multivalent functions.