Bound pair states beyond the condensate for Fermi systems below T_c: the pseudogap as a necessary condition

A. Yu. Cherny, A. A. Shanenko

As is known, the 1/q^2 theorem of Bogoliubov asserts that the mean density of the fermion pair states with the total momentum q obeys the inequality n_q > C/q^2 (q \to 0) in the ca…