Аннотация:Within the quark composite model taking into account interaction with QCD vacuum condensates
the hadron electro-magnetic mass differences are calculated. The total mass difference is determined by the sum of contributions of 1) the electromagnetic interaction of quarks, 2) the dependence of the quark kinetic energy on their masses, and 3) the effect of d-,
u-quark mass difference on strong interaction potential. The consideration of the quark interaction through the QCD vacuum gives good descriptions of experimental data. The difference of masses of d- and u-quarks is estimated: m a - m, = 3.7 MeV.