Threshold Upsilon-meson Photoproduction at EIC and EicC

Abstract

High-accuracy $\hat{I}\yen$-meson photoproduction data from EIC and EicC experiments will allow the measurement of the near-threshold total cross section of the reaction ${\hat{I}}^{3}p\to \hat{I}\yen p$, from which the absolute value of the $\hat{I}\yen p$ scattering length, $|\hat{I}{\pm }_{\hat{I}\yen p}|$, can be extracted using a Vector-Meson Dominance model. For this evaluation, we used $\hat{I}\yen$-meson photoproduction quasi-data from the QCD approach (the production amplitude can be factorized in terms of gluonic generalized parton distributions and the quarkonium distribution amplitude). A comparative analysis of $|\hat{I}{\pm }_{\hat{I}\yen p}|$ with the recently determined scattering lengths for $\ddot{I}‰p$, $\ddot{I}•p$, and $J/\ddot{I}ˆp$ using the A2, CLAS, and GlueX experimental data are performed. The role of the "young" vector-meson effect is evaluated.

6 pages, 6 figures, 3 tables