Low-energy QCD: Chiral coefficients and the quark-quark interaction.

A detailed investigation of the low-energy chiral expansion is presented within a model truncation of QCD. The truncation allows for a phenomenological description of the quark-quark interaction in a framework which maintains the global symmetries of QCD and permits a 1/Nc expansion. The model dependence of the chiral coefficients is tested for several forms of the quarkquark interaction by varying the form of the running coupling, α(q), in the infrared region. The pattern in the coefficients that arises at tree level is consistent with large Nc QCD, and is related to the model truncation.