Structure change of Cooper pairs in color superconductivity -- Crossover from BCS to BEC ? --

Abstract

We discuss a possibility of transition from color superconductivity of the standard BCS type at high density, to Bose-Einstein Condensation (BEC) of Cooper pairs at lower density. Examining two-flavor QCD over a wide range of baryon density, we found the size of a Cooper pair becomes small enough to be comparable to the averaged quark-quark distance at lower density. We also consider the same problem in two-color QCD.

Comments: 4pages, 2figures, Contribution to the Proceedings of "Quark Matter 2002", Nantes, France, 18-24 Jul 2002