Mass spectrum of the hidden-charm pentaquarks in the compact diquark model

Understand

The LHCb collaboration have recently updated their analysis of the resonant $J/\psi p$ mass spectrum in the decay $\Lambda_b^0 \to J/\psi p K^-$, making use of their combined Run 1 and Run 2 data.

• In the updated analysis, three narrow states, $P_c (4312)^+$, $P_c (4440)^+$,and $P_c (4457)^+$, are observed.
• The spin-parity assignments of these states are not yet known.
• We interpret these narrow resonances as compact hidden-charm diquark-diquark-antiquark pentaquarks.