Probing the hidden-bottom pentaquark resonances in photonuclear bottomonium production near threshold: differential observables

TL;DR

This paper investigates the potential to detect hidden-bottom pentaquark states through differential observables in near-threshold photonuclear production of Upsilon(1S) mesons on protons and nuclei, aiming to guide future experimental searches.

Contribution

It introduces a detailed theoretical analysis of resonant and non-resonant bottomonium production, proposing specific observables to identify hidden-bottom pentaquark states in upcoming collider experiments.

Findings

Predicted energy and momentum distributions for Upsilon(1S) production.

Identified optimal conditions for observing pentaquark resonances.

Provided decay rate estimates for hypothetical pentaquark states.

Abstract

We study the near-threshold $\Upsilon(1S)$ meson photoproduction from protons and nuclei by considering incoherent direct non-resonant (${\gamma}p \to {\Upsilon(1S)}p$, ${\gamma}n \to {\Upsilon(1S)}n$) and two-step resonant (${\gamma}p \to P^+_{bi} \to {\Upsilon(1S)}p$, ${\gamma}n \to P^0_{bi} \to {\Upsilon(1S)}n$, $i=1$, 2, 3; $P^{+,0}_{b1}=P^{+,0}_{b}(11080)$, $P^{+,0}_{b2}=P^{+,0}_{b}(11125)$, $P^{+,0}_{b3}=P^{+,0}_{b}(11130)$) bottomonium production processes with the main goal of clarifying the possibility to observe the non-strange hidden-bottom pentaquark states $P^{+,0}_{bi}$ in this production via differential observables. We calculate the absolute excitation functions, energy and momentum distributions for the non-resonant, resonant and for the combined (non-resonant plus resonant) production of $\Upsilon(1S)$ mesons on protons, on carbon and tungsten target nuclei at near-threshold incident photon beam energies by assuming the spin-parity assignments of the hypothetical hidden-bottom resonances $P^{+,0}_{b}(11080)$, $P^{+,0}_{b}(11125)$ and $P^{+,0}_{b}(11130)$ as $J^P=(1/2)^-$, $J^P=(1/2)^-$ and $J^P=(3/2)^-$ within four different realistic choices for the branching ratios of their decays to the ${\Upsilon}(1S)p$ and ${\Upsilon}(1S)n$ modes (0.125, 0.25, 0.5 and 1\%) as well as for two options for the background contribution. We demonstrate that the measurements of these combined observables on proton and nuclear targets in the near-threshold energy region in future experiments at the planned high-luminosity electron-ion colliders EIC and EicC in the US and China should provide evidence for the existence of the above hidden-bottom pentaquark resonances as well as clarify their decay rates.