One-loop analysis of the interactions between doubly charmed baryons and Nambu-Goldstone bosons

The interactions between the spin-$1/2$ doubly charmed baryons and Nambu-Goldstone bosons are analyzed within a manifestly relativistic baryon chiral perturbation theory up to next-to-next-to leading order, by using the so-called extended-on-mass-shell scheme. We utilize heavy diquark-antiquark symmetry to estimate the low-energy constants in the chiral effective Lagrangians. The $S$- and $P$-wave scattering lengths are predicted. We find that those diagrams, vanishing exactly in the heavy-quark limit, do contribute slightly to the $S$-wave scattering lengths in reality. The influence of the spin-$3/2$ doubly charmed baryons, as heavy-quark spin partners of the spin-$1/2$ ones, on the scattering lengths is discussed as well. Finally, $S$-wave phase shifts for elastic scattering processes are presented in the energy region near threshold. Our results in this work will not only be very useful for performing chiral extrapolations of future lattice QCD data, but also provide us chiral inputs for the investigation of the spectroscopy of doubly heavy baryons.