HEAVY MESON HYPERFINE SPLITTING - A COMPLETE 1 M(Q) CALCULATION/

The hyperfine splittings Delta D = (m(Ds) - m(Ds)) - (m(D*+) - m(D+)) and Delta(B) = (m(Bs) - m(Bs)) - (m(B*0) - m(B0)) are analyzed in th e framework of an effective lagrangian possessing chiral, heavy flavou r and spin symmetries, explicitly broken by a complete set of first or der terms. Among these terms, those responsible for the difference bet ween the couplings g(PP*pi) and g(P*P pi) are evaluated in the QCD su m rules approach. Their contribution to Delta(D) and to Delta(B) appea rs to quantitatively balance previously estimated chiral effects, in n ice agreement with the experimental data, solving a suspected puzzle f or heavy quark theory.