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

TL;DR

This study explores the potential observation of hidden-bottom pentaquark resonances through near-threshold photoproduction of Upsilon(1S) mesons on protons and nuclei, providing theoretical predictions for future high-precision experiments.

Contribution

It offers the first detailed theoretical analysis of Upsilon(1S) photoproduction near threshold, including resonance contributions from hypothesized pentaquark states, to guide future experimental searches.

Findings

Predicted excitation functions for Upsilon(1S) production on protons and nuclei.

Identified energy regions where pentaquark signals could be observed.

Provided cross section estimates to distinguish resonant from non-resonant production.

Abstract

We study the $\Upsilon(1S)$ 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 $E_{\gamma}$ below 68.8 GeV). We calculate the absolute excitation functions for the non-resonant and resonant photoproduction of $\Upsilon(1S)$ mesons off protons at incident photon laboratory energies of 63--68 GeV by accounting for direct (${\gamma}p \to {\Upsilon(1S)}p$) and two-step (${\gamma}p \to P^+_b(11080,11125,11130) \to {\Upsilon(1S)}p$) $\Upsilon(1S)$ production channels within different scenarios for the non-resonant total cross section of elementary reaction ${\gamma}p \to {\Upsilon(1S)}p$ and for branching ratios of the decays $P^+_b(11080,11125,11130) \to {\Upsilon(1S)}p$. We also calculate an analogous functions for photoproduction of $\Upsilon(1S)$ 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 (${\gamma}N \to {\Upsilon(1S)}N$) and two-step (${\gamma}p \to P^+_b(11080,11125,11130) \to {\Upsilon(1S)}p$, ${\gamma}n \to P^0_b(11080,11125,11130) \to {\Upsilon(1S)}n$) $\Upsilon(1S)$ production processes within a nuclear spectral function approach. We show that a detailed scan of the $\Upsilon(1S)$ 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.