Masses of the pseudo Nambu-Goldstone bosons in the two flavor color superconducting phase

The masses of the pseudo Nambu-Goldstone bosons in the color superconducting phase of dense QCD with two light flavors are estimated by making use of the Cornwall-Jackiw-Tomboulis effective action. Parametrically, the masses of the doublet and antidoublet bosons are suppressed by a power of the coupling constant as compared to the value of the superconducting gap. This is qualitatively different from the mass expression for the singlet pseudo Nambu-Goldstone boson, resulting from nonperturbative effects. It is argued that the (anti) doublet pseudo Nambu-Goldstone bosons form colorless [with respect to the unbroken SU(2)_c] charmonium-like bound states. The corresponding binding energy is also estimated.