Meson-loop contributions to the quark condensate from the instanton vacuum
Abstract
We investigate the quark condensate of the QCD vacuum within the instanton vacuum model. We calculate the meson-loop contributions to the dynamical quark mass and quark condensate to
O(1/
N
c
)
-,
O(m/
N
c
)
-, and
O((mlnm)/
N
c
)
-order corrections. We find that the meson (especially pion) loops provide substantial contributions to the dynamical quark mass and as a result to the quark condensate. The results indicate that the
1/
N
c
corrections should be reconsidered in the systematical way. The present results are consistent with those from chiral perturbation theory.