Universal enhancement of the pairing gap in a dilute Fermi superfluid

At zero temperature, a dilute Fermi gas with an attractive contact interaction forms a superfluid with gapped fermionic excitations. We show that the gap at weak coupling can be organized as a trans-series expansion in the interaction strength and the asymptotic Gor'kov-Melik-Barkhudarov gap. Low-energy virtual quasiparticles generate corrections that are linear in the gap with a leading coefficient nearly 25$\times$ larger than the other known coefficients. This substantially increases the gap at intermediate densities, highlighting that systematic corrections are crucial for quantitative predictions.

Source: arXiv:2610.20434v1 - http://arxiv.org/abs/2610.20434v1 PDF: https://arxiv.org/pdf/2610.20434v1 Original Link: http://arxiv.org/abs/2610.20434v1