The equilibrium between the so-called 2SC and CFL phases of strange quark matter at high densities is investigated in the framework of a simple schematic model of the NJL type .
Equal densities are assumed for quarks u,d and s .
The 2SC phase is here described by a color-flavor symmetric state , in which the quark numbers are independent of the color-flavor combination .
In the CFL phase the quark numbers depend on the color-flavor combination , that is , the number of quarks associated with the color-flavor combinations ur,dg,sb is different from the number of quarks associated with the color flavor combinations ug,ub,dr,db,sr,sg .
We find that the 2SC phase is stable for a chemical potential \mu below \mu _ { c } = 0.505 GeV , while the CFL phase is stable above , the equilibrium pressure being P _ { c } = 0.003 GeV ^ { 4 } .
We have used a 3-momentum regularizing cutoff \Lambda = 0.8 GeV , which is somewhat larger than is usual in NJL type models .
This should be adequate if the relevant chemical potential does not exceed 0.6 GeV .