Low energy constants of \chiPT from the instanton vacuum model
arXiv:0707.1997 · doi:10.1103/PhysRevD.76.076007
Abstract
In the framework of the instanton vacuum model we make expansion over the current mass m and number of colors N_c and evaluate -corrections to the dynamical quark mass M, the quark condensate , the pion mass M_πand decay constant F_π. 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/N_c-corrections to dynamical mass are large and mostly come from meson loops. As a consequence, we have large 1/N_c-corrections to all the other quantities. To provide the values of $F_π(m=0), \ave{\bar qq(m=0)}$ in agreement with \chiPT, we offer a new set of parameters ρ, R. Finally, we find the low-energy SU(2)_f chiral lagrangian constants in a rather good correspondence with the phenomenology.