Pentaquarks and resonances in the $pJ\mathrm{/}\psi$ spectrum

We consider exotic baryons with hidden charm as antiquark-diquark-diquark composite systems. Spin and isospin structure of such exotic states is given and masses are estimated. The data for production of pentaquarks in the reaction ${\mathrm{\Lambda }}_b\to K^{-}pJ\mathrm{/}\psi$ are discussed. We suggest that the narrow peak in $pJ\mathrm{/}\psi$ spectra at 4450 MeV is antiquark-diquark-diquark state with negative parity, $5\mathrm{/}{2}^{-}(4450)$, while the broad bump $3\mathrm{/}{2}^{+}(4380)$ is the result of rescatterings in the ($pJ\mathrm{/}\psi$)-channel. Positions of other pentaquarks with negative parity are estimated.