Light axial-vector and vector resonances $X(2100)$ and $X(2239)$

Abstract

We study features of the resonances $X(2100)$ and $X(2239)$ by treating them as the axial-vector and vector tetraquarks with the quark content $ss\overline{s}\overline{s}$, respectively. The spectroscopic parameters of these exotic mesons are calculated in the framework of the QCD two-point sum rule method. Obtained prediction for the mass $m=(2067\pm 84)\mathrm{MeV}$ of the axial-vector state is in excellent agreement with the mass of the structure $X(2100)$ recently observed by the BESIII Collaboration in the decay $J/\psi \to \varphi \eta {\eta }^{\prime }$ as the resonance in the $\varphi {\eta }^{\prime }$ mass spectrum. We explore also the $S$-wave decays $X(2100)\to \varphi {\eta }^{\prime }$ and $X(2100)\to \varphi \eta$ using the QCD light-cone sum rule approach and technical methods of the soft-meson approximation. The width of the axial-vector tetraquark, $\Gamma =(130.2\pm 30.1)\mathrm{MeV}$, saturated by these two decays is comparable with the measured full width of the resonance $X(2100)$. Our prediction for the vector $ss\overline{s}\overline{s}$ tetraquark's mass $\tilde{m}=(2283\pm 114)\mathrm{MeV}$ is consistent with the experimental result $2239.2\pm 7.1\pm 11.3\mathrm{MeV}$ of the BESIII Collaboration for the mass of the resonance $X(2239)$.

Comments: 9 Pages and 3 Figures