New scalar resonance X 0(2900) as a molecule: mass and width

Abstract

We explore features of the scalar structure X 0(2900), which is one of the two resonances discovered recently by LHCb in the D − K + invariant mass distribution in the decay B + → D + D − K +. We treat X 0(2900) as a hadronic molecule composed of the conventional mesons and K ∗0 and calculate its mass, coupling and width. The mass and coupling of X 0(2900) are determined using the QCD two-point sum rule method by taking into account quark, gluon, and mixing vacuum condensates up to dimension 15. The decay of this structure to final state D − K + is investigated in the context of the light-cone sum rule approach supported by a soft-meson technique. To this end, we evaluate strong coupling G corresponding to vertex X 0 D − K +, which allows us to find width of the decay X 0(2900) → D − K +. Obtained predictions for the mass of the hadronic molecule and for its width Γ = (49.6 ± 9.3) MeV can be considered as arguments in favor of molecule interpretation of X 0(2900).