JLab and J-PARC for the J/{\ensuremathψ} Production at the Threshold

New threshold measurements for $γ~p\to p~J/ψ\to p~(μ^+μ^-)$ by 007 and $γ^\ast~p\to p~J/ψ\to p~(e^+e^-)$ by CLAS12 allow us to extend the previous phenomenological determination of the J/\ensuremathψ-proton scattering length, $α_{J/ψp}$, using GlueX threshold data for $γ~p\to p~J/ψ\to p~(e^+e^-)$. The agreement between all three J/\ensuremathψ data sets shows no indication of systematic differences between methodologies. Furthermore, perturbative QCD predictions support the phenomenological determination of heavy vector meson-nucleon scattering lengths. Upcoming J-PARC threshold measurements of the reaction $π^-~p\to n~J/ψ\to n~(l^+l^-)$ will help resolve a puzzle regarding the trend of the vector meson-nucleon scattering lengths, $|α_{Υp}| \ll |α_{J/ψp}| \ll |α_{φp}| \ll |α_{ωp}|$, which is consistent with the ``young vector meson'' hypothesis.