Precise value of the σ-meson mass used in CDF parameterizations

Determine the precise vacuum mass of the σ meson employed in covariant density functional parameterizations (e.g., DD-ME), which is intended to represent the two–pion–exchange contribution to the nuclear force, and quantify its impact on infinite nuclear matter properties within the CDF framework.

Background

In the CDF model setup, nucleons interact via σ, ω, and ρ mesons. While ω and ρ masses are well established, the σ meson mass—used to encapsulate two–π exchange—is not precisely known and is typically taken around 500 MeV. The authors note that properties of infinite nuclear matter depend only on coupling-to-mass ratios and that variations in mσ can be absorbed into gσ, but the lack of a precise mσ remains a fundamental uncertainty in the parametrization.

Clarifying the σ-meson mass would better anchor the meson–nucleon vertex functions and could reduce ambiguities in mapping microscopic inputs to macroscopic nuclear and compact-star observables within the density-dependent CDF framework.