ϕ meson self-energy in nuclear matter from ϕN resonant interactions

Abstract

The φ-meson properties in cold nuclear matter are investigated by implementing resonant φN interactions as described in effective approaches including the unitarization of scattering amplitudes. Several N * -like states are dynamically generated in these models around 2 GeV, in the vicinity of the φN threshold. We find that both these states and the non-resonant part of the amplitude contribute sizably to the φ collisional self-energy at finite nuclear density. These contributions are of a similar strength as the widely studied medium effects from theKK cloud. Depending on model details (position of the resonances and strength of the coupling to φN ) we report a φ broadening up to about 40-50 MeV, to be added to the φ →KK in-medium decay width, and an attractive optical potential at threshold up to about 35 MeV at normal matter density. The φ spectral function develops a double peak structure as a consequence of the mixing of resonance-hole modes with the φ quasi-particle peak. The former results point in the direction of making up for missing absorption as reported in φ nuclear production experiments.

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

“…This is consistent with the rather small mass drop of about -2 to -3% at nuclear matter density (see Fig. 43) predicted by Hatsuda and Lee [19], Cabrera et al [245,246] and Cobos-Martinez et al [247]. More recently an even smaller reduction of the φ meson mass in the nuclear medium of less than -2 % has been predicted [248,249].…”

“…The latter value is much smaller than the indirect determinations of the in-medium φ width, discussed above. A lowering of the φ mass by 35 MeV is, however, in the range of some theoretical predictions [19,245], while Klingl et al [132] and Gubler and Weise [248,249] expect smaller mass modifications. From the only available measurement, the real part of the φ-nucleus potential is thus ≈ -35 MeV.…”

Strangeness in nuclei and neutron stars

“…In Ref. [194] two different coupled-channel approaches for the φN interactions have been considered: (6)), and the KC and the resonant φN scattering from the hidden-gauge scheme (KC+HLS). These plots are taken from Ref.…”

The ϕ meson with finite momentum in a dense medium

“…Moreover, even though we have assumed the φ meson width to be zero in our analysis, this is not the case in reality (see for instance Refs. [30,31]). Thus, to have a more realistic idea about the behavior of the dilepton spectrum at normal nuclear matter density and non-zero momentum, we artificially introduce a width using the relativistic Breit-Wigner form,…”