Aspects of meson properties in dense nuclear matter

Le résumé fourni par la source

We investigate the modification of meson spectral densities in dense nuclear matter at zero temperature. These effects are studied in a fully relativistic mean field model which goes beyond the linear density approximation and also includes baryon resonances. In particular, the role of ${N}^{*}(1520)$ and ${N}^{*}(1720)$ on the $\ensuremath{\rho}$ meson spectral density is highlighted. Even though the nucleon-nucleon loop and the nucleon-resonance loop contribute with the opposite sign, an overall reduction of $\ensuremath{\rho}$ meson mass is still observed at high density. Importantly, it is shown that the resonances cause substantial broadening of the $\ensuremath{\rho}$ meson spectral density in matter and also induce nontrivial momentum dependence. We study the dispersion relations and collective oscillations induced by the $\ensuremath{\rho}$ meson propagation in nuclear matter together with the influence of the mixing of $\ensuremath{\rho}$ with the ${a}_{0}$ meson. The relevant expression for the plasma frequency is also recovered analytically in the appropriate limit. The spectral density of the ${a}_{0}$ meson is also shown.

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