Two-gluon form factor of the nucleon and J/ψ photoproduction

We argue that the t dependence of the two-gluon form factor of the nucleon should be given by Γ(t) = (1 -t/m_2g²)-² with m_2g² ≈ 1 GeV². We demonstrate that this form provides a good description of the t dependence of the cross section of the elastic photoproduction of J/ψ mesons between the threshold region of E_γ = 11 GeV (Cornell), E_γ = 19 GeV (SLAC) and E_γ= 100 GeV (Fermilab), including the strong energy dependence of the t slope. It is also well matched with the recent DESY HERA data. The same assumption explains also the t dependence of φ-meson electroproduction near threshold at W=2.3 GeV, Q² = 1.0 GeV².