Phase structure of quark systems in models with four-fermion interaction

Condensated fermion system in the model of four-quark interaction with large correlation length

“…The opposite limit of infinite correlation length (δ-function like behavior in momentum space) is widely used in condensed matter physics and known as the Keldysh model [4]. Realizing that for the strongly interacting systems the size of characteristic vacuum box is found of Λ −1 QCD order [5] we could qualitatively expect that both opposite models lead to practically the same picture of spontaneous chiral symmetry breaking, color superconductivity and some important features, because a scale of coupling constant G can be properly tuned by using meson observables [6], [7].…”

“…For the delta-like potential in coordinate space (NJL model) the expression (7) diverges and to obtain the reasonable results the cut-off upper limit over momentum integration Λ is introduced, which along with the coupling constant G and current quark mass m is one of the tuning model parameter. Below we use one of the standard parameter sets for the NJL model [9]: Λ = 631 MeV, GΛ 2 /(2π 2 ) ≈ 1.3, m = 5 MeV while the KKB model parameters are chosen in such a way that for the same current masses the quark dynamical masses in both NJL and KKB models coincide at vanishing quark momentum.…”