ISOSPIN VIOLATION IN QCD SUM-RULES FOR BARYONS

We thoroughly analyze isospin-violating effects in QCD sum rules for t he masses of nucleons, SIGMA, and XI hyperons. After comparing with ex perimental mass splittings in isotopic multiplets, we obtain for the i sospin breaking in the quark condensate [0\uuBAR - ddBAR\0]/[0\uuBAR\0 ] = (2+/-1)X 10(-3), a value significantly smaller than the one usuall y adopted. We present arguments in favor of our result and critically analyze previous estimates. The value of the quark mass difference m(d ) - m(u) = 3.0+/-1.0 MeV (at normalization point muBAR = 0.5 GeV) is a lso determined.