Twistors of nonlocal vertex algebras

In this paper we introduce and study the concept of twistor for a nonlocal vertex algebra. This concept provides a unified framework for various constructions of nonlocal vertex algebras, such as R-matrices, twisted tensor products, iterated twisted tensor products and L-R-twisted tensor products of nonlocal vertex algebras. Among the main results, we find the relations among theses constructions and we also give one concrete example of a twistor. Furthermore, we study some properties of twistors.