H. Leutwyler
Published 2001-07-31Version 1
The role of the quark condensate for the low energy structure of QCD is discussed in some detail. In particular, the dependence of M_pi on m_u and m_d and the low energy theorems for the pi-pi scattering amplitude are reviewed. The new data on Ke4 decay beautifully confirm the standard picture, according to which the quark condensate is the leading order parameter of the spontaneously broken chiral symmetry.
Comments: Talk given at the Workshop QCD@Work, Martina Franca, June 2001
Journal: AIP Conf.Proc. 602 (2001) 3-13
Meson-loop contributions to the quark condensate from the instanton vacuum
Volume behaviour of quark condensate, pion mass and decay constant from Dyson-Schwinger equations
One-meson-loop NJL model: Effect of collective and noncollective excitations on the quark condensate at finite temperature
