2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/82699Determinations of the gluon propagator in the continuum and in lattice simulations are compared. A systematic truncation procedure for the quark Dyson-Schwinger and bound state Bethe-Salpeter equations is described. The procedure ensures the flavour-octet axial-vector Ward identity is satisfied order-by-order, thereby guaranteeing the preservation of Goldstone's theorem; and identifies a mechanism that simultaneously ensures the absence of diquarks in QCD and their presence in QCD$^{N_c=2}$, where the colour singlet diquark is the ``baryon'' of the theory.7 pages, LaTeX, uses sprocl.sty and epsfig, contribution to the proceedings of ``Quark Confinement and the Hadron Spectrum''Nuclear TheoryHigh Energy Physics - Phenomenologytext