New scalar resonance $X_0(2900)$ as a ${\overline{D}}^{\ast }{K}^{\ast }$ 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 ${\overline{D}}^{\ast 0}$ and $K^{\ast 0}$ 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 $X_0(2900)\to D^{-}{K}^{+}$. Obtained predictions for the mass of the hadronic molecule ${\overline{D}}^{\ast 0}{K}^{\ast 0}$ $m=(2868\pm 198)\mathrm{MeV}$ and for its width $\hat{I}“=(49.6\pm 9.3)\mathrm{MeV}$ can be considered as arguments in favor of molecule interpretation of $X_0(2900)$.

9 Pages, 1 Figure and 1 Table