rho-Meson Nucleon Scattering Length from CLAS Threshold Photoproduction Measurements

Abstract

Extending our study of the vector meson-nucleon scattering lengths (summary is given in Ref.~\cite{Strakovsky:2021vyk}), we are focusing on the $\ddot{I}$-meson case using recent CLAS threshold data for the reaction ${\hat{I}}^{3}p\to \ddot{I}p$ within the meson-baryon reaction model~\cite{CLAS:2018drk}. The total $\ddot{I}{ƒ}_t({\hat{I}}^{3}p\to \ddot{I}p)$ and $\ddot{I}{ƒ}_t({\hat{I}}^{3}p\to \ddot{I}‰p)$ cross sections are close below the momentum of the vector meson in CM $q=0.2GeV/c$. Then the $\ddot{I}p$ photoproduction cross section grows rapidly. Our result for $\ddot{I}N$ scattering length is a factor of 4 smaller than the size of the hadron and the phenomenological determination of the $\ddot{I}‰$ nucleon scattering length using threshold photoproduction cross sections. The observed difference between $\ddot{I}N$ and $\ddot{I}‰N$ scattering lengths is of interest for further understanding within the hadron structure theory.

5 pages, 3 figures, 1 table