Heavy meson hyperfine splitting: a complete 1mQ calculation

The hyperfine splittings Δd = (mds∗ − mnds) − (md∗+ − md+) and Δd = (mbs∗ − mbs) − (mb∗0 − mb0) are analyzed in the framework of an effective lagrangian possessing chiral, heavy flavour and spin symmetries, explicitly broken by a complete set of first order terms. Among these terms, those responsible for the difference between the couplings gp∗p∗π and gp∗pπ are evaluated in the QCD sum rules approach. Their contribution to Δd and to Δb appears to quantitatively balance previously estimated chiral effects, in nice agreement with the experimental data, solving a suspected puzzle for heavy quark theory.