Probing hidden-bottom pentaquarks in fixed-target collisions at the LHC

In this paper we investigate the possibility of searching for the hidden-bottom pentaquark states in photon-induced interactions at the LHC. We consider the presence of the $P_b$ resonance in the $s$-channel of the $\gamma p \rightarrow \Upsilon p$ reaction and estimate its contribution for the exclusive $\Upsilon$ photoproduction in the fixed-target mode of the LHC. Predictions for the total cross sections, rapidity and transverse momentum distributions are derived using the STARlight Monte Carlo considering $Pb-p$, $Pb-He$ and $Pb-Ar$ fixed-target collisions at the LHC. Our results indicate that the presence of the $P_b$ resonance implies an enhancement in the rapidity distribution in the kinematical range covered by the LHCb detector. We demonstrate that the $P_b$ contribution for the $\Upsilon$ photoproduction becomes dominant if kinematical cuts are imposed on the rapidity and transverse momentum of the final state. These results indicate that an experimental analysis of the $\Upsilon$ photoproduction in fixed-target collisions can provide complementary and independent checks of the existence of these states, and help to understand their underlying nature.