Protons in High Density Neutron Matter

Misak M Sargsian

doi:10.1088/1742-6596/496/1/012007

Abstract

We discuss the possible implication of the recent predictions of two new properties of high momentum distribution of nucleons in asymmetric nuclei for neutron star dynamics. The first property is about the approximate scaling relation between proton and neutron high momentum distributions weighted by their relative fractions (xp and xn) in the nucleus. The second is the existence of inverse proportionality of the high momentum distribution strength of protons and neutrons to xp/n. Based on these predictions we model the high momentum distribution functions for asymmetric nuclei and demonstrate that it describes reasonably well the high momentum characteristics of light nuclei. We also extrapolate our results to heavy nuclei as well as infinite nuclear matter and calculate the relative fractions of protons and neutrons with momenta above kF. Our results indicate that for neutron stars starting at three nuclear saturation densities the protons with xp = 1/9 will populate mostly the high momentum tail of the momentum distribution while only 2% of the neutrons will do so. Such a situation may have many implications for different observations of neutron stars which we discuss.

Highlights

One of the exciting recent results in the studies of short-range correlations (SRCs) in nuclei is the observation of the strong dominance of the pn SRCs, relative to the pp and nn correlations, for nuclear internal momenta of ∼ 300 − 600 MeV/c[1, 2]. This observation is understood[1, 3, 4] based on the dominance of the tensor forces in NN interaction at the above mentioned momenta corresponding to average nucleon separations of ∼ 1 Fm
At these distances the dominating NN central potential crosses the zero due to transition from attractive to repulsive interaction allowing tensor forces to dominate in this transition range
As a results pp and nn components of the NN SRC will be strongly suppressed since they are dominated by the central NN potential with relative L = 0

Summary

Introduction

One of the exciting recent results in the studies of short-range correlations (SRCs) in nuclei is the observation of the strong (by factor of 20) dominance of the pn SRCs, relative to the pp and nn correlations, for nuclear internal momenta of ∼ 300 − 600 MeV/c[1, 2] This observation is understood[1, 3, 4] based on the dominance of the tensor forces in NN interaction at the above mentioned momenta corresponding to average nucleon separations of ∼ 1 Fm. This observation is understood[1, 3, 4] based on the dominance of the tensor forces in NN interaction at the above mentioned momenta corresponding to average nucleon separations of ∼ 1 Fm At these distances the dominating NN central potential crosses the zero due to transition from attractive to repulsive interaction allowing tensor forces to dominate in this transition range. The goal of our study is to understand the implication of the above described conditions on the the momentum distribution of protons and neutrons in high density nuclei matter

New Relation between High Momentum p- and n-distributions in Nuclei

High Momentum Features of Light Nuclei

High Momentum Properties of Heavy Nuclei

High Momentum Properties of Asymmetric Nuclear Matter

Findings

Possible Implications for Nuclei and Neutron Stars