Analysis of the Λ_c(2625) and Xi_c(2815) with QCD sum rules

In this article, we study the charmed baryon states $\Lambda_c(2625)$ and $\Xi_c(2815)$ with the spin-parity ${3\over 2}^-$ by subtracting the contributions from the corresponding charmed baryon states with the spin-parity ${3\over 2}^+$ using the QCD sum rules, and suggest a formula $ \mu=\sqrt{M_{\Lambda_c/\Xi_c}^2-{\mathbb{M}}_c^2}$ with the effective mass ${\mathbb{M}}_c=1.8\,\rm{GeV}$ to determine the energy scales of the QCD spectral densities, and make reasonable predictions for the masses and pole residues. The numerical results indicate that the $\Lambda_c(2625)$ and $\Xi_c(2815)$ have at least two remarkable under-structures.