We pointed out in this work that in dealing with the BEC-BCS crossover problem, the dynamic effect of <b(t)>is not negligible. Accordingly, an equation of motion approach was devised to calculate the Green′s functions. Based on our result, we concluded that instead of crossover, BCS states and Bose-Einstein condensation always coexist.
@article{arxiv.cond-mat/0504775,
title = {A study on the coexistence of BEC and BCS states},
author = {C. D. Hu},
journal= {arXiv preprint arXiv:cond-mat/0504775},
year = {2007}
}