Diquarks in the color--flavor locked phase of dense quark matter

Abstract

Diquark excitations of dense quark matter are considered in the framework of the Nambu -- Jona-Lasinio model with three types of massless quarks in the presense of a quark number chemical potential $\mu$. We investigate the effective action of meson- and diquark fields at sufficiently high values of $\mu$, where the color--flavor locked (CFL) phase is realized, and prove the existence of NG-bosons in the sector of pseudoscalar diquarks. In the sector of scalar diquarks an additional NG-boson is found, corresponding to the spontaneous breaking of the U(1)$_B$ baryon symmetry in the CFL phase. Finally, the existence of massive scalar and pseudoscalar diquark excitations is demonstrated.