On the structure of the scalar and D mesons

The $q\bar{q}$ spectrum is studied within a chiral constituent quark model. It provides with a good fit of the available experimental data from light (vector and pseudoscalar) to heavy mesons. The new $D$ states measured at different factories are studied. The $0^{++}$ light mesons are analyzed as $q\bar{q}$ pairs or tetraquark structures.