Isospin Symmetry Breaking in the Quark Condensates, $<\bar{d}d>/=<\bar{u}u>$, as Estimated from QCD Sum Rules

W-Y. P. Hwang, Kwei-Chou Yang

Isospin symmetry breaking in the quark condensates, $<\bar{d}d>/=<\bar{u}u>$, is a fundamental parameter in both the QCD sum rule studies and the chiral perturbation theory. I…