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 presence 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 $\mathrm{U}(1{)}_B$ baryon symmetry in the CFL phase. Finally, the existence of massive scalar and pseudoscalar diquark excitations is demonstrated.

• Received 1 December 2006

DOI:https://doi.org/10.1103/PhysRevD.75.045005