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

Abstract

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 $V_{lowk}$, 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 anti-screening, i.e., pairing is enhanced. This enhancement is mostly due to the strongly attractive Landau parameter $f_0$. We discuss in detail the critical temperature $T_c$ in the limit of low densities and show that the suppression of $T_c$ predicted by Gor'kov and Melik-Barkhudarov can only be reproduced if the cutoff of the $V_{lowk}$ interaction is scaled with the Fermi momentum. We also discuss the effect of non-condensed pairs on the density dependence of $T_c$ in the framework of the Nozières-Schmitt-Rink theory.

16 pages, 16 figures; v2: added references, one table, and ancillary files containing matrix elements of the screened pairing interaction

References in corpus (14)

• The BCS-BEC crossover: From ultra-cold Fermi gases to nuclear systems
• Screening Effects in Superfluid Nuclear and Neutron Matter within Brueckner Theory
• Equation of state of superfluid neutron matter and the calculation of ${}^1{S}_0$ pairing gap
• Low-momentum interactions with smooth cutoffs
• BCS-BEC crossover of neutron pairs in symmetric and asymmetric nuclear matter
• Renormalization Group Theory for the Imbalanced Fermi Gas
• Particle-hole fluctuations in the BCS-BEC Crossover
• Convergence of the Born Series with Low-Momentum Interactions
• Pairing in neutron matter: New uncertainty estimates and three-body forces
• Entanglement between pairing and screening in the Gorkov-Melik-Barkhudarov correction to the critical temperature throughout the BCS-BEC crossover
• Dependence of the BCS 1S0 superfluid pairing gap on nuclear interactions
• Pairing and short-range correlations in nuclear systems
• Three-nucleon forces and superfluidity in neutron matter
• Upper edge of the neutron star crust : the drip point and around

Cited by in corpus (14)

• Neutron Stars and the Nuclear Equation of State
• Equation of Motion Method to strongly correlated Fermi systems and Extended RPA approaches
• Superfluid Phase Transitions and Effects of Thermal Pairing Fluctuations in Asymmetric Nuclear Matter
• Neutron pairing with medium polarization beyond the Landau approximation
• Pairing in pure neutron matter
• Equation of state of superfluid neutron matter with low-momentum interactions
• Nuclear superfluidity at finite temperature
• From odd-even staggering to the pairing gap in neutron matter
• Generalized Crossover in Interacting Fermions within the Low-Energy Expansion
• Mean-Field Theory for Fermion Pairs and the ab initio Particle-Vibration-Coupling Approach
• BCS-BEC Crossover Effects and Pseudogap in Neutron Matter
• Low-momentum interactions for ultracold Fermi gases
• Induced three-neutron interactions with low cutoffs for dilute neutron matter
• Hartree shift and pairing gap in ultracold Fermi gases in the framework of low-momentum interactions