$P_{cc}^N$ 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 $D^{(*)} \Sigma_c^{(*)}$ 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 $5/2^-$ $D^*\Sigma_c^*$ channel, three states with binding energy $26$, $30$ and $7$ MeV (relative to the thresholds from low to high, respectively) in the $3/2^-$ $D\Sigma_c^*$-$D^*\Sigma_c$-$D^*\Sigma_c^*$ system and three states with binding energy $32$, $8$ and $16$ MeV in the $1/2^-$ $D\Sigma_c$-$D^*\Sigma_c$-$D^*\Sigma_c^*$ 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.