Single $\Lambda_c^+$ hypernuclei within quark mean-field model

Abstract

The quark mean-field (QMF) model is applied to study the single $\Lambda^+_c$ hypernuclei. The charm baryon, $\Lambda^+_c$, is constructed by three constituent quarks, $u, ~d$, and $c$, confined by central harmonic oscillator potentials. The confinement potential strength of charm quark is determined by fitting the experimental masses of charm baryons, $\Lambda^+_c,~\Sigma^+_c$, and $\Xi^{++}_{cc}$. The effects of pions and gluons are also considered to describe the baryons at the quark level. The baryons in $\Lambda^+_c$ hypernuclei interact with each other through exchanging the $\sigma,~\omega$, and $\rho$ mesons between the quarks confined in different baryons. The $\Lambda^+_c N$ potential in the QMF model is strongly dependent on the coupling constant between $\omega$ meson and $\Lambda^+_c$, $g_{\omega\Lambda^+_c}$. When the conventional quark counting rule is used, i. e., $g_{\omega\Lambda^+_c}=2/3g_{\omega N}$, the massive $\Lambda^+_c$ hypernucleus can exist, whose single $\Lambda^+_c$ binding energy is smaller with the mass number increasing due to the strong Coulomb repulsion between $\Lambda^+_c$ and protons. When $g_{\omega\Lambda^+_c}$ is fixed by the latest lattice $\Lambda^+_c N$ potential, the $\Lambda^+_c$ hypernuclei only can exist up to $A\sim 50$.