Mesons and diquarks in the CFL phase of dense quark matter

The spectrum of meson and diquark excitations of the color–flavor locked (CFL) phase of dense quark matter is considered in the framework of the Nambu – JonaLasinio model. We have found that in this phase all Nambu–Goldstone bosons are realized as scalar and pseudoscalar diquarks. Other diquark excitations are resonances with mass value around 230 MeV. Mesons are stable particles in the CFL phase. Their masses vs chemical potential lie in the interval 300÷500 MeV. It is well-known that at asymptotically high baryon densities the ground state of massless three-flavor QCD corresponds to the so-called color – flavor locked (CFL) phase [1]. One of the most noticeable differences between color superconductivity phenomena with three and two quark species is that the CFL effect is characterized by a hierarchy of energy scales. Indeed, at the lowest scale of this phase lie NG bosons, which dominate in all physical processes with energies smaller than the superconducting gap ∆. Evident contributors at higher energy scales are quark quasiparticles, which in the CFL phase have an energy greater than ∆. However, up to now we know much less about other excitations, whose energy and mass are of the order of ∆ in magnitude. Among these particles are ordinary scalar and pseudoscalar mesons, massive diquarks etc, i.e. particles which might play an essencial role in dynamical processes of the CFL phase. Here we are going to discuss just this type of excitations of the CFL ground state, i.e. mesons and massive diquarks, in the framework of the massless three-flavor NJL model with Lagrangian L = q̄ [