Prediction of exotic doubly charmed baryons within chiral effective field theory

Abstract: In this work we study the possible QCD exotic states in the doubly charmed baryon sector. Within chiral effective theory, it is predicted that several excited baryons result from the $S$-wave scattering of ground-state doubly charmed baryons ($\Xi_{cc}^{++}, \Xi_{cc}^{+}, \Omega_{cc}^{+}$) and light pseudoscalar mesons ($\pi, K, \eta$). The excited doubly charmed baryons can be classified by the strangeness ($S$) and isospin ($I$) quantum numbers. Two of the excited states are clearly exotic, in the sense that they cannot be explained by the conventional baryons with three quarks, since their quantum numbers are $(S,I)=(1,0)$ and $(-1,1)$. Similar to the charmed scalar meson $D_{s0}^{*}(2317)$ in $DK$ scattering and the hyperon $\Lambda(1405)$ in $\bar{K}N$ scattering, one bound state below the $\Xi_{cc} \bar{K}$ threshold is predicted in the $(S,I)=(-1,0)$ channel. In addition, two resonant structures are found in the $\Xi_{cc}\pi, \Xi_{cc}\eta$ and $\Omega_{cc} K$ coupled-channel scattering with $(S,I)=(0,1/2)$. The corresponding pole positions and coupling strengths of the excited doubly charmed baryons are given. The scattering lengths of the ground-state doubly charmed baryons and light pseudoscalar mesons are also predicted. The current study may provide useful guides for future experimental measurements and lattice simulations.