Short-Range Correlations and Urca Process in Neutron Stars

TL;DR

This paper investigates how short-range correlations in neutron stars affect the Urca process, revealing significant deviations from traditional Fermi-liquid theory predictions, which could influence star cooling models.

Contribution

It introduces a calculation of the Urca process rate incorporating non-Fermi liquid effects from short-range correlations, a novel approach in neutron star physics.

Findings

Urca rate differs from Fermi-liquid predictions at low temperatures.

High proton fraction threshold for Urca process is replaced by a smooth increase.

Implications for neutron star cooling theories.

Abstract

Recent measurements of high-momentum correlated neutron-proton pairs at JLab suggest that the dense nucleonic component of the compact stars contains a fraction of high-momentum neutron-proton pairs that is not accounted for in the familiar Fermi-liquid theory of the neutron-proton fluid mixture. We compute the rate of the Urca process in compact stars taking into account the non-Fermi liquid contributions to the proton's spectral widths induced by short-range correlations. The Urca rate differs strongly from the Fermi-liquid prediction at low temperatures, in particular, the high threshold on the proton fraction precluding the Urca process in neutron stars is replaced by a smooth increase with the proton fraction. This observation may have a profound impact on the theories of cooling of compact stars.