Test of φ renormalization in nuclei through φ photoproduction

We propose an experimental procedure to find out the medium modifications of the φ meson. The reaction is inclusive φ photoproduction in nuclei, looking for K+K− pairs from the φ decay with total momentum smaller than 100–150 MeV/c, which are made possible at energies of present laboratories from center of mass φ backward production and the help of Fermi motion. We have conducted a many body calculation of the mass distribution of the φ adapted to the experimental set up of a recent JLAB experiment where the backwards φ photoproduction has been measured. Using recent results for the in medium properties of the φ, we find that the width of the invariant mass distribution for photoproduction on medium to heavy nuclei is larger than the free φ width by a factor of two or more.