QCD sum rules study of QQ−u¯d¯ mesons

We use QCD sum rules to study the possible existence of QQ−u¯d¯ mesons, assumed to be a state with JP=1+. For definiteness, we work with a current with an axial heavy diquark and a scalar light anti-diquark, at leading order in αs. We consider the contributions of condensates up to dimension eight. For the b-quark, we predict MTbb=(10.2±0.3)GeV, which is below the B¯B¯∗ threshold. For the c-quark, we predict MTcc=(4.0±0.2)GeV, in agreement with quark model predictions.