Investigation of constraints on few-neutron forces in neutron matter by empirical information on the neutron skin of 48Ca and 208Pb

TL;DR

This paper uses chiral effective field theory to calculate neutron matter properties and explores how neutron skin measurements in 48Ca and 208Pb can constrain few-neutron forces, with implications for nuclear physics and neutron-rich matter.

Contribution

It provides a systematic analysis of neutron matter equations of state up to fifth order and discusses how empirical neutron skin data can limit few-neutron force models.

Findings

Neutron skins in 48Ca and 208Pb can constrain three-neutron forces.

Order-by-order convergence supports the reliability of chiral EFT predictions.

Theoretical uncertainties are quantified for future experimental comparisons.

Abstract

The neutron matter equation of state is calculated from two-neutron forces up to fifth order of the chiral expansion and the order-by-order convergence of the predictions is investigated. Based on these equations of state, the binding energies and the neutron and proton density distributions in 208Pb and 48Ca are derived, with particular attention to the neutron skins, the focal point of this paper. Anticipating future experiments which will provide reliable information on the weak charge density in nuclei, the theoretical uncertainties and the possibility of constraining the size of few-neutron forces in neutron matter are discussed.