New scalar resonance $X_0(2900)$ as a $\overline{D}^{*}K^{*}$ 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 $B^{+} \to D^{+}D^{-}K^{+}$. We treat $ X_0(2900)$ as a hadronic molecule composed of the conventional mesons $ \overline{D}^{* 0} $ 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 $X_0D^{-}K^{+}$, which allows us to find width of the decay $X_0(2900) \to D^{-}K^{+}$. Obtained predictions for the mass of the hadronic molecule $\overline{D}^{*0 }K^{*0}$ $m=(2868 \pm 198)~\mathrm{MeV} $ and for its width $\Gamma=(49.6 \pm 9.3)~ \mathrm{MeV}$ can be considered as arguments in favor of molecule interpretation of $X_0(2900)$.