Enhancement near the $\overline{p}\mathrm{\Lambda }$ threshold in the ${\chi }_{c0}\to \overline{p}{K}^{+}\mathrm{\Lambda }$ reaction

We have analyzed the reaction ${\chi }_{c0}\to \overline{p}{K}^{+}\mathrm{\Lambda }$ reported by the BESIII Collaboration, taking into account the contributions from the intermediate $K(1830)$, $N(2300)$, and $\mathrm{\Lambda }(1520)$ resonances. Our results are in good agreement with the BESIII measurements, and it is found that the anomalous enhancement near the $\overline{p}\mathrm{\Lambda }$ threshold is mainly due to the contribution of the $K(1830)$ resonance. We also show that the interference of the high-mass $N^{*}$ and ${\mathrm{\Lambda }}^{*}$ can not produce the anomalous enhancement near the $\overline{p}\mathrm{\Lambda }$ threshold.

Figure 1

The diagram for the reaction ${\chi }_{c0}\to \overline{p}{K}^{+}\mathrm{\Lambda }$, (a) the direct diagram, (b) the contribution from the intermediate $K(1830)$ resonance, (c) the contribution from the intermediate $N(2300)$ resonance, and (d) the contribution from the intermediate $\mathrm{\Lambda }(1520)$ resonance.

Figure 2

The $\overline{p}\mathrm{\Lambda }$ (a), $\overline{p}{K}^{+}$ (b), and $\mathrm{\Lambda }{K}^{+}$ (c) mass distributions for the reaction ${\chi }_{c0}\to \overline{p}{K}^{+}\mathrm{\Lambda }$. The curves labeled as “direct,” “$K^{*}$,” “$N(2300)$,” and “$\mathrm{\Lambda }(1520)$” show the contributions of Figs. 1, 1, 1, and 1, respectively, and the curves labeled as “$\mathrm{direct}+K^{*}$” are the contributions of the direct term and the intermediate $K(1830)$ state in Eq. (2). The “total” curves correspond to the total contribution of Eq. (1). The BESIII data are taken from Ref. [10].

Figure 3

The $\overline{p}\mathrm{\Lambda }$ (a), $\overline{p}{K}^{+}$ (b), and $\mathrm{\Lambda }{K}^{+}$ (c) mass distributions for the reaction ${\chi }_{c0}\to \overline{p}{K}^{+}\mathrm{\Lambda }$, by taking the mass and width of $K(1830)$ as free parameters. The explanations of the curves are the same as those of Fig. 2.

Figure 4

The diagram for the contribution from the intermediate high-mass ${\mathrm{\Lambda }}^{*}$ resonance.

Figure 5

The $\overline{p}\mathrm{\Lambda }$ (a), $\overline{p}{K}^{+}$ (b), and $\mathrm{\Lambda }{K}^{+}$ (c) mass distributions including the $N(2300)$ and high mass $\mathrm{\Lambda }$ state. The curves labeled as “direct,” “$N(2300)$,” and “${\mathrm{\Lambda }}^{*}$” show the contributions of the Figs. 1, 1, and Fig. 4, respectively, and the curves labeled as “direct+${\mathrm{\Lambda }}^{*}$” are the contribution of the direct term and the intermediate ${\mathrm{\Lambda }}^{*}$ state,. The “total” curves correspond to the total contribution of Eq. (12). The BESIII data are taken from Ref. [10].

Figure 6

The Daliz plots for the ${\chi }_{c0}\to \overline{p}{K}^{+}\mathrm{\Lambda }$.

Figure 7

Data for $d\mathrm{\Gamma }/d{M}_{\overline{p}\mathrm{\Lambda }}$ divided by the phase space of Eq. (7).