Inhomogeneous condensates in dilute nuclear matter and BCS-BEC crossovers

Martin Stein,Armen Sedrakian,Xu-Guang Huang,Gerd Röpke,John W Clark

doi:10.1088/1742-6596/496/1/012008

Abstract

We report on recent progress in understanding pairing phenomena in low-density nuclear matter at small and moderate isospin asymmetry. A rich phase diagram has been found comprising various superfluid phases that include a homogeneous and phase-separated BEC phase of deuterons at low density and a homogeneous BCS phase, an inhomogeneous LOFF phase, and a phase-separated BCS phase at higher densities. The transition from the BEC phases to the BCS phases is characterized in terms of the evolution, from strong to weak coupling, of the condensate wavefunction and the second moment of its density distribution in r-space. We briefly discuss approaches to higher-order clustering in low-density nuclear matter.

Highlights

The two-nucleon interactions in nuclear matter at sub-saturation densities are well constrained by the phase-shift data and analysis of elastic nucleonnucleon collisions, facilitating a quantitative many-body description of nuclear matter in this regime
In supernovae the nuclear matter is at finite isospin asymmetry which, is small compared to that of cold β-catalyzed neutron star matter
In this contribution we review some recent progress in establishing the nature of pairing in low-density nuclear matter

Summary

Introduction

The two-nucleon interactions in nuclear matter at sub-saturation densities (below about half the saturation density) are well constrained by the phase-shift data and analysis of elastic nucleonnucleon collisions, facilitating a quantitative many-body description of nuclear matter in this regime. 2. Pairing If we restrict ourselves to only two-body correlations, nuclear matter at extremely low density is a mixture of quasi-free nucleons and deuterons, the only effect of the interaction being to renormalize the mass of the constituents. The concepts of unconventional SD pairing and the BCS-BEC crossover were unified in a model of isospin-asymmetric nuclear matter [9] by including some of the phases mentioned above.

Results

Conclusion