$$^1S_0$$ 1 S 0 Pairing in Neutron Matter

Abstract

We report calculations of the superfluid pairing gap in neutron matter for the 1 S 0 components of the Reid soft-core V 6 and the Argonne V ′ 4 two-nucleon interactions. Ground-state calculations have been carried out using the central part of the operator-basis representation of these interactions to determine optimal Jastrow-Feenberg correlations and corresponding effective pairing interactions within the correlated-basis formalism (CBF), the required matrix elements in the correlated basis being evaluated by Fermi hypernetted-chain techniques. Different implementations of the Fermi-Hypernetted Chain Euler-Lagrange method (FHNC-EL) agree at the percent level up to nuclear matter saturation density. For the assumed interactions, which are realistic within the low density range involved in 1 S 0 neutron pairing, we did not find a dimerization instability arising from divergence of the in-medium scattering length, as was reported recently for simple square-well and Lennard-Jones potential models (Phys. Rev. A 92, 023640 (2015)).

Superfluidity in nuclear systems and neutron stars

“…It reveals a property of BCS pairing that is awkward from the computational standpoint: the exponential sensitivity of the energy gap to variations of the pairing interaction. Studies of pairing in neutron matter within Gor'kov-Melik-Barkhudarov theory [58] and its extensions, especially to finite-range corrections, have been carried out in [59,60]. For extensions to multicomponent systems and Fermi-Bose mixtures of cold gases, see [61].…”

“…It was applied to nucleonic pairing at the early stages of theoretical development of this generic quantum many-body theory [17][18][19]23]. Since that time, the CBF method has undergone extensive further developments, with applications in diverse physical contexts, in particular to nuclear systems [60,[216][217][218][219][220][221] and the low-density fermionic gas [222].…”

“…. As applied, this approach and the one outlined here have complementary strengths and weaknesses [60,222,223].…”

Axion cooling of neutron stars. II. Beyond hadronic axions

“…As an alternative we use the computation of Ref. [44] where the pairing interaction resums both long-and short-range correlation in an approximated way. The resulting gap is significantly larger, the maxima differing by a factor ∼ 2.5.…”

“…8 as a function of neutron (proton) Fermi momentum. (a) neutron 1 S0-gaps according to WAP [43] and FCK [44]; (b) critical temperature of 3 P2-3 F2 superfluid neutron phase transition according to models a and b of Ref. [45]; (c) critical temperature of 1 S0 superfluid proton phase transition according to T73 [42] and CCDK [46].…”