  In the low energy domain, Chiral Perturbation Theory parametrizes the small
chiral symmetry breaking effects, produced by the quark masses $m_u$, $m_d$ and
$m_s$, in terms of order parameters of massless QCD. The latter can then, in
principle, be measured in high precision, low energy experiments. We discuss
several relevant processes and possible improvements at future high luminosity
tau/charm or K factories. (talk given at the XXVIIIth Rencontres de Moriond on
QCD and High Energy Hadronic Interactions, Les Arcs (France), March 20-27
1993.)
