QCD corrections to QED and isospin breaking in the baryon spectrum and vector-meson mixing

Abstract

We reexamine baryon isomultiplet mass splittings and $\rho -\omega$ mixing including, in addition to the usual one-photon-exchange terms and the light-quark mass difference $\Delta m(=m_d-m_u)$, effective charge-symmetry-breaking operators due to the interference of QED and QCD. We find that these interference terms play a significant role in determining the isomultiplet splittings and that including them in the analysis reduces the extracted value of $\Delta m$.