Accessing the real part of the forward $J/\psi$-p scattering amplitude from $J/\psi$ photo-production on protons around threshold

Oleksii Gryniuk, Marc Vanderhaeghen

We provide an updated analysis of the forward $J/\psi$-p scattering amplitude, relating its imaginary part to $\gamma p\to J/\psi p$ and $\gamma p\to c\bar{c}X$ cross section data, and calculating…