Search for Hidden-Strangeness Pentaquark State from φ photoproduction

Following the discovery of the $P_c$ states, the existence of their strange partners is anticipated. We are performing a search for a possible hidden-strangeness pentaquark state via the $\gamma d \to \phi p n$ reaction at the LEPS beamline of SPring-8. The final-state $K^{+}$, $K^{-}$ from $\phi$-meson decay and proton are detected using the forward magnetic spectrometer. Possible excesses in the $\phi p$ and $\phi n$ invariant mass spectra in photoreactions on the deuteron are investigated by comparing the experimental data with Monte Carlo simulations.