Charmed nuclei within a microscopic many-body approach
Single-particle energies of the $Λ_c$ chamed baryon are obtained in several nuclei from the relevant self-energy constructed within the framework of a perturbative many-body approach. Results are presented for a charmed baryon-nucleon ($Y_cN$) potential based on a SU(4) extension of the meson-exchange hyperon-nucleon potential $\tilde A$ of the Jülich group. Three different models (A, B and C) of this interaction, that differ only on the values of the couplings of the scalar $σ$ meson with the charmed baryons, are considered. Phase shifts, scattering lengths and effective ranges are computed for the three models and compared with those predicted by the $Y_cN$ interaction derived in Eur. Phys. A {\bf 54}, 199 (2018) from the extrapolation to the physical pion mass of recent results of the HAL QCD Collaboration. Qualitative agreement is found for two of the models (B and C) considered. Our results for $Λ_c$-nuclei are compatible with those obtained by other authors based on different models and methods. We find a small spin-orbit splitting of the $p-, d-$ and $f-$wave states as in the case of single $Λ$-hypernuclei. The level spacing of $Λ_c$ single-particle energies is found to be smaller than that of the corresponding one for hypernuclei. The role of the Coulomb potential and the effect of the coupling of the $Λ_cN$ and $Σ_cN$ channels on the single-particle properties of $Λ_c-$nuclei are also analyzed. Our results show that, despite the Coulomb repulsion between the $Λ_c$ and the protons, even the less attractive one of our $Y_cN$ models (model C) is able to bind the $Λ_c$ in all the nuclei considered. The effect of the $Λ_cN-Σ_cN$ coupling is found to be almost negligible due to the large mass difference of the $Λ_c$ and $Σ_c$ baryons.