P${}_{cc}^N$ states in a unitarized coupled-channel approach

Starting from an effective Lagrangian with heavy quark spin symmetry embedded, the coupled-channel dynamics of the doubly charmed systems D${}^{(\ast )}$Σ${}_c^{(\ast )}$ is investigated. The potential underlying our investigation includes t-channel pseudoscalar and vector meson exchanges. A series of S-wave bound states with isospin I = 1/2 is found by applying the first iterated solution of the N/D method: one state with binding energy 23 MeV in the 5/2${}^{-}$ D*Σ${}_c^{\ast }$ channel, three states with binding energy 26, 30 and 7 MeV (relative to the thresholds from low to high, respectively) in the 3/2${}^{-}$ DΣ${}_c^{\ast }$-D*Σ${}_c$-D*Σ${}_c^{\ast }$ system and three states with binding energy 32, 8 and 16 MeV in the 1/2${}^{-}$ DΣ${}_c$-D*Σ${}_c$-D*Σ${}_c^{\ast }$ system. Those P${}_{cc}^N$ states serve as the open-charm partners of the hidden charm pentaquarks P${}_{\psi }^N$ observed by the LHCb Collaboration.