Diquark-Antidiquark with open charm in QCD sum rules

Using the QCD sum rule approach we investigate the possible four-quark structure of the recently observed charmed scalar mesons (BELLE) and (FOCUS) and also of the very narrow , firstly observed by BABAR. We use diquak-antidiquark currents and work to the order of ms in full QCD, without relying on 1/mc expansion. Our results indicate that a four-quark structure is acceptable for the resonances observed by BELLE and BABAR: and respectively, but not for the resonances observed by FOCUS: .