We use diquark-antidiquark currents to investigate the masses and partial decay widths of the recently observed mesons D+sJ(2317), D*0(0)(2308) and X(3872), considered as four-quark states, in a QCD sum rule approach. In particular we investigate the coupling constant gDsJ DK. We found that the gDsJ DK obtained in this four-quark scenario is smaller than the coupling constant obtained when D+sJ(2317) is considered as a conventional cs state.

We calculate the masses of lambdab and lambdac in the framework of QCD sum rules including instanton contributions. We find that these contributions have the same size of the four quark condensate contribution and improve the Borel stability in both Dirac structures of the baryon correlation function.