Low energy constants of from the instanton vacuum model
Abstract
In the framework of the instanton vacuum model we make expansion over the current mass m and number of colors Nc and evaluate O(1/Nc, m, m/Nc, m m/Nc)-corrections to the dynamical quark mass M, the quark condensate < qq>, the pion mass Mπ and decay constant Fπ. There are several sources of these corrections: meson loops, finite size of the instanton distribution and the quark-quark "tensor" interaction terms. In contrast to the expectations, we found that numerically the 1/Nc-corrections to dynamical mass are large and mostly come from meson loops. As a consequence, we have large 1/Nc-corrections to all the other quantities. To provide the values of Fπ(m=0), qq(m=0) in agreement with , we offer a new set of parameters , R. Finally, we find the low-energy SU(2)f chiral lagrangian constants l3, l4 in a rather good correspondence with the phenomenology.