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 including some recent results on charmonium. The $0^{ ++}$ light mesons and the new $D$ states measured at different factories cannot be described as $q\bar q$ pairs and a tetraquark structure is suggested.
Categories: hep-ph