In-Medium Properties of the ϕ Meson with ϕ N Resonant Contributions

Abstract

Nuclear production experiments report missing absorption processes of the in-medium ϕ meson. Contributions arising from theKK cloud have already been widely studied, and therefore we investigate the ϕ-meson's properties in cold nuclear matter with the additional inclusion of resonant ϕ N interactions. Two models are considered which dynamically generate N * -like states close to the ϕ N threshold. We find that these states, together with the non-resonant part of the amplitude, contribute to the ϕ self-energy with the same order of magnitude as theKK effects. At non-vanishing nuclear density, both models lead to an additional in-medium broadening of the ϕ, up to around 50 MeV. Furthermore, at least one of the models is compatible with a mass shift to lower energies of up to 35 MeV at threshold and normal matter density. Finally, a double-peak structure appears in the spectral function due to the mixing of resonance-hole modes with the ϕ quasi-particle peak. These results converge into the direction of the experimental findings.

Meson–nucleus potentials and the search for meson–nucleus bound states

“…Within the QMC model a width of 33 -37 MeV is predicted [247]. In addition to the in-medium φ → KK decay, Cabrera et al [253] discuss contributions to the φ width from the coupling to nucleon resonances yielding an additional broadening of the order of 40-50 MeV.…”