Ground-state energy of the unitary Fermi gas from the epsilon expansion

Abstract

We update the ground-state energy ratio of unitary Fermi gas to noninteracting Fermi gas (xi) from the epsilon expansion by including the next-to-next-to-leading-order (NNLO) term near two spatial dimensions. Interpolations of the NNLO epsilon expansions around four and two spatial dimensions with the use of Pade approximants give xi=0.360+/-0.020 in three dimensions with the uncertainty due to different interpolation functions. This value is consistent with the previous interpolations of the NLO epsilon expansions xi=0.377+/-0.014 in spite of the large NNLO corrections.