Quarks lourds, spectroscopie des

Two issues in [Formula: see text] spectroscopy are discussed. The calculation of the hadronic transitions of the triplet D state is reviewed showing that the radiative transitions remain the best signature for this state. A model, which was proposed to explain the anomalous spectra of the pions in the [Formula: see text] transition, is reviewed. The inclusion of a four-quark resonance in the [Formula: see text] channel, together with π + π − final-state interactions, may explain the presence of two peaks in the [Formula: see text] spectrum.