Testing the ϕ-nuclear potential in pion-induced ϕ meson production on nuclei near threshold

Abstract

The near-threshold pion-induced ϕ production off nuclei has been studied in the kinematical conditions of the HADES experiment using a collision model based on the nuclear spectral function. Starting from the elementary reaction π−p→ϕn, absolute differential and integral cross sections for the production of ϕ mesons off a light carbon and a heavy tungsten target have been calculated and compared to the recently reported experimental cross sections. The absolute cross section values are shown to be sensitive to the effective nuclear scalar ϕ and neutron potentials while the transparency ratio is governed by the ϕN absorption cross section. The experimental data are found to be consistent with an attractive ϕ-nucleus potential of ≈ -(50–100) MeV at normal nuclear matter density ρ0 and an effective ϕN absorption cross section of ≈ 12–25 mb. The extracted ϕ-nucleus potential is deeper than previous theoretical and experimental findings as well as those obtained in the present work within the (tρ) approximation with accounting for Pauli correlations from the spin-averaged ϕ-p scattering length reported in a recent ALICE experiment.