Quantum Monte Carlo study of dilute neutron matter at finite temperatures

Abstract

We report results of fully non-perturbative, Path Integral Monte Carlo (PIMC) calculations for dilute neutron matter. The neutron-neutron interaction in the s channel is parameterized by the scattering length and the effective range. We calculate the energy and the chemical potential as a function of temperature at the density $\dens=0.003\fm^{-3}$. The critical temperature $\Tc$ for the superfluid-normal phase transition is estimated from the finite size scaling of the condensate fraction. At low temperatures we extract the spectral weight function $A(p,\omega )$ from the imaginary time propagator using the methods of maximum entropy and singular value decomposition. We determine the quasiparticle spectrum, which can be accurately parameterized by three parameters: an effective mass $m^{\ast }$, a mean-field potential $U$, and a gap $\Delta$. Large value of $Δ/\Tc$ indicates that the system is not a BCS-type superfluid at low temperatures.

4 pages, 3 figures

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• Correlations in Nuclear Matter
• Condensate Fraction in Neutron Matter
• LINPRO: linear inverse problem library for data contaminated by statistical noise
• Causality bounds for neutron-proton scattering
• Fermionic condensation in ultracold atoms, nuclear matter and neutron stars