2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/26290We 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$^{\prime}$s functions. Based on our result, we concluded that instead of crossover, BCS states and Bose-Einstein condensation always coexist.8 pages, 3figuresSuperconductivityStrongly Correlated Electronstext