We study hadronic molecular states in a coupled system of $J/\psi N - \Lambda_c\bar{ D}^{ (*)} - \Sigma_c^{ (*)}\bar{ D}^{ (*)}$ in $I(J^P) = \frac{ 1}{ 2}(\frac{ 3}{ 2}^-)$ channel, using the complex scaling method combined with the Gaussian expansion method. We construct the potential including one pion exchange and one $D^{ (*)}$ meson exchange with $S$-wave orbital angular momentum. We find that the both mass and width of the pentaquark $P_c(4380)$ can be reproduced within a reasonable parameter region, and that its main decay mode is $\Lambda_c\bar{ D}^*$. We extend our analysis to a coupled system of $\Lambda_c D^{ (*)} - \Sigma_c^{ (*)}D^{ (*)}$ in $I(J^P) = \frac{ 1}{ 2}(\frac{ 3}{ 2}^-)$ channel. We find that there exists a doubly charmed baryon of $ccqq\bar{ q}$ type as a hadronic molecule, the mass and width of which are quite close to those of $P_c(4380)$.
Categories: hep-ph nucl-th