We study pure neutron matter in the BEC-BCS crossover regime using renormalization-group-based low-momentum interactions within the Nozières-Schmitt-Rink framework. This is an attempt to go beyond the mean-field description for low-density matter. We work in the basis of so-called Weinberg eigenvectors where the operator G0V is diagonal, which proves to be an excellent choice that allows one to use nonlocal interactions in a very convenient way. We study the importance of correlations as a function of density. We notice that there is a significant reduction of the BCS critical temperature at low densities as the neutron matter approaches the unitary limit. © 2013 American Physical Society.

Sunethra Ramanan

Department Of Physics

M. Urban

Fulltext

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Physical Review C - Nuclear Physics

We study pairing in low-density neutron matter including the screening interaction due to the exchange of particle-hole and RPA excitations. As bare force, we employ the effective low-momentum interaction Vlowk, while the Fermi-liquid parameters are taken from a phenomenological energy density functional (SLy4) which correctly reproduces the equation of state of neutron matter. At low density, we find screening, i.e., pairing is reduced, while at higher densities, we find antiscreening, i.e., pairing is enhanced. This enhancement is mostly due to the strongly attractive Landau parameter f0. We discuss in detail the critical temperature Tc in the limit of low densities and show that the suppression of Tc predicted by Gor'kov and Melik-Barkhudarov can only be reproduced if the cutoff of the Vlowk interaction is scaled with the Fermi momentum. We also discuss the effect of noncondensed pairs on the density dependence of Tc in the framework of the Nozières-Schmitt-Rink theory. © 2018 American Physical Society.

Physical Review C

Screening and antiscreening of the pairing interaction in low-density neutron matter

We study the zero-temperature BCS gaps for the triplet channel in pure neutron matter using similarity renormalization group (SRG) evolved interactions. We use the dependence of the results on the SRG resolution scale as a tool to analyze medium and many-body corrections. In particular, we study the effects of including the three-body interactions at leading order, which appear at next-to-next-to leading order (N2LO) in the chiral effective field theory (EFT), as well as that of the first-order self-energy corrections on the zero-temperature gap. In addition we also extract the transition temperature as a function of densities and verify the BCS scaling of the zero-temperature gaps to the transition temperature. We observe that the self-energy effects are very crucial in order to reduce the SRG resolution scale dependence of the results, while the three-body effects at the leading order do not change the two-body resolution scale dependence. On the other hand, the results depend strongly on the three-body cutoff, emphasizing the importance of the missing higher-order three-body effects. We also observe that self-energy effects reduce the overall gap as well as shift the gap closure to lower densities. © 2016 American Physical Society.

Triplet pairing in pure neutron matter

Journal of Physics: Conference Series

Pairing correlations in exotic nuclei

Science

Revealing the Superfluid Lambda Transition in the Universal Thermodynamics of a Unitary Fermi Gas

BEC-BCS crossover and the liquid-gas phase transition in hot and dense nuclear matter

Chiral three-nucleon forces and neutron matter

Progress in Particle and Nuclear Physics

From low-momentum interactions to nuclear structure

BEC-BCS crossover in neutron matter with renormalization-group-based effective interactions

Journal	Data powered by TypesetPhysical Review C - Nuclear Physics
Publisher	Data powered by TypesetAmerican Physical Society
ISSN	05562813
Open Access	No