Understanding open-charm mesons

We present a theoretical framework that accounts for the new DJ and DsJ mesons measured in the open-charm sector. These resonances are properly described if considered as a mixture of conventional P−wave quark-antiquark states and four-quark components. The narrowest states are basically P−wave quark-antiquark mesons, while the dominantly four-quark states are shifted above the corresponding two-meson threshold. We study the electromagnetic decay widths as basic tools to scrutiny their nature.