Pion-assisted charmed dibaryon candidate

The ${\mathrm{\Lambda }}_c(2286)N$ system is studied in a chiral constituent quark model, and the resulting $s$-wave interaction is used in separable form within three-body models of the $\pi {\mathrm{\Lambda }}_{c}N$ system with quantum numbers $(C,I,J^P)=(+1,\frac{3}{2},2^{+})$. Separable interactions are also used for the dominant $p$-wave pion-baryon channels dominated by the $\mathrm{\Delta }(1232)$ and ${\mathrm{\Sigma }}_c(2520)$ resonances. Faddeev equations with relativistic kinematics are solved on the real axis to search for bound states and in the complex plane to search for three-body resonances. Some of the models considered generate a very narrow bound state, requiring isospin violation for its strong decay. Other models lead to a narrow resonance ($\mathrm{\Gamma }\lesssim 0.4\mathrm{MeV}$) for a resonance mass below the ${\mathrm{\Sigma }}_c(2455)N$ threshold. This would be the lowest-lying $C=+1$ dibaryon, with mass estimated as $\approx 3370\pm 15\mathrm{MeV}$.

Figure 1

Left: CCQM ${\mathrm{\Lambda }}_{c}N$ local potentials in the ${}^3{S}_1$ channel for several values of the charmed quark harmonic oscillator size parameter $b_c$. Right: corresponding ${\mathrm{\Lambda }}_{c}N{}^3{S}_1$ phase shifts, in solid (dashed) lines, produced by the CCQM local (separable) potentials. The smaller $b_c$ is, the higher the maximum of the phase shift $\delta$ is.