2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/186752I discuss briefly the instabilities of two flavor quark matter, paying attention to the gradient instability which develops in the g2SC phase in the Goldstone $U(1)_A$ sector.6 pages. Talk given at QCD@Work07, Martina Franca (Italy). Some typos corrected, one reference addedHigh Energy Physics - Phenomenologytext