Implications of PREX-II on the equation of state of neutron-rich matter

TL;DR

This paper discusses how recent measurements of neutron skin thickness in lead-208 influence the understanding of the symmetry energy's density dependence and its implications for neutron star properties.

Contribution

It provides a new estimate of the symmetry energy slope L based on PREX-II data, highlighting a potential overestimation compared to previous constraints.

Findings

PREX-II measurement suggests a stiffer symmetry energy.

The estimated L value is (106 +/- 37) MeV, higher than previous limits.

Implications for neutron star observables are analyzed.

Abstract

Laboratory experiments sensitive to the equation of state of neutron rich matter in the vicinity of nuclear saturation density provide the first rung in a "density ladder" that connects terrestrial experiments to astronomical observations. In this context, the neutron skin thickness of 208Pb (Rskin) provides a stringent laboratory constraint on the density dependence of the symmetry energy. In turn, an improved value of Rskin has been reported recently by the PREX collaboration. Exploiting the strong correlation between Rskin and the slope of the symmetry energy L within a specific class of relativistic energy density functionals, we report a value of L=(106 +/- 37)MeV -- that systematically overestimates current limits based on both theoretical approaches and experimental measurements. The impact of such a stiff symmetry energy on some critical neutron-star observables is also examined.