Study of a possibility of observation of hidden-bottom pentaquark resonances in bottomonium photoproduction on protons and nuclei near threshold

Abstract

We study the $Υ(1S)$ meson photoproduction on protons and nuclei at the near-threshold center-of-mass energies below 11.4 GeV (or at the corresponding photon laboratory energies $E_γ$ below 68.8 GeV). We calculate the absolute excitation functions for the non-resonant and resonant photoproduction of $Υ(1S)$ mesons off protons at incident photon laboratory energies of 63--68 GeV by accounting for direct ($γp \to {Υ(1S)}p$) and two-step ($γp \to P^+_b(11080,11125,11130) \to {Υ(1S)}p$) $Υ(1S)$ production channels within different scenarios for the non-resonant total cross section of elementary reaction $γp \to {Υ(1S)}p$ and for branching ratios of the decays $P^+_b(11080,11125,11130) \to {Υ(1S)}p$. We also calculate an analogous functions for photoproduction of $Υ(1S)$ mesons on $^{12}$C and $^{208}$Pb target nuclei in the near-threshold center-of-mass beam energy region of 9.0--11.4 GeV by considering respective incoherent direct ($γN \to {Υ(1S)}N$) and two-step ($γp \to P^+_b(11080,11125,11130) \to {Υ(1S)}p$, $γn \to P^0_b(11080,11125,11130) \to {Υ(1S)}n$) $Υ(1S)$ production processes within a nuclear spectral function approach. We show that a detailed scan of the $Υ(1S)$ total photoproduction cross section on a proton and nuclear targets in the near-threshold energy region in future high-precision experiments at the proposed high-luminosity electron-ion colliders EIC and EicC in the U.S. and China should give a definite result for or against the existence of the non-strange hidden-bottom pentaquark states $P_{bi}^+$ and $P_{bi}^0$ ($i=$1, 2, 3) as well as clarify their decay rates.