Nonlocal and local ghost fields in quantum correlations.

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, it is shown that quantum mechanics can be cast in a way that has the form of either nonpositive and local ghost field or a positive and nonlocal ghost field.