$\lambda$, $\rho$, and $\sigma$ Regge trajectories for the hexaquark ${(\bar{u}(cc))(b(\bar{b}\bar{b}))}$ in the triquark-antitriquark picture

Abstract

We propose Regge trajectory relations for the hexaquark ${(\bar{u}(cc))(b(\bar{b}\bar{b}))}$ by using the Regge trajectory relations for diquarks and triquarks. With these newly derived relations, we investigate five series of hexaquark Regge trajectories: the $\lambda$-, $\rho_1$-, $\rho_2$-, $\sigma_1$-, and $\sigma_2$-trajectories. We demonstrate that, apart from the simplest $\lambda_1$-trajectories, the $\rho_1$-, $\rho_2$-, $\sigma_1$-, and $\sigma_2$-trajectories cannot be constructed by merely mimicking the meson Regge trajectories, since mesons possess no internal substructures. To derive these trajectories, one must account for the structure and internal substructure of hexaquark. Without this structural information, the $\rho_1$-, $\rho_2$-, $\sigma_1$-, and $\sigma_2$-trajectories could only be obtained through direct fits to available theoretical predictions or future experimental data. We demonstrate that the $\rho_1$-, $\rho_2$-, $\sigma_1$-, and $\sigma_2$-trajectories for the hexaquark do not correspond respectively to the Regge trajectories for the triquark, antitriquark, diquark, and antidiquark. Nevertheless, their behaviors match those of the Regge trajectories for the triquark $(\bar{u}(cc))$, the antitriquark $(b(\bar{b}\bar{b}))$, the diquark $(cc)$, and the antidiquark $(\bar{b}\bar{b})$, in that respective order. Furthermore, we present rough mass estimates for the excited states corresponding to the $\lambda$-, $\rho_1$-, $\rho_2$-, $\sigma_1$-, and $\sigma_2$-trajectories.