Non-local and local ghost fields in quantum correlations

Abstract Einstein-Podolsky-Rosen quantum correlations are discussed from the perspective of a ghost field introduced by Einstein. The concepts of ghost field, hidden variables, local reality and the Bell inequality are reviewed. In the framework of the correlated singlet state of two spin-½ particles, it is shown that quantum mechanics can be cast in a way that has the form of either a non-positive and local ghost field or a positive and non-local ghost field.