{ "id": "cond-mat/0501080", "version": "v3", "published": "2005-01-05T14:42:40.000Z", "updated": "2005-09-12T12:41:48.000Z", "title": "Phase Separation and an upper bound for $Δ$ for Fermi fluids in the Phase Separation and an upper bound for $Δ$ for Fermi fluids in the unitary regime", "authors": [ "Thomas D. Cohen" ], "comment": "This is the version to be publishd. The notation has been improved to match standard useage. An improved discussion on the implication of the nature of the bound and the physical meaning of the parameter Delta", "journal": "Phys.Rev.Lett.95:120403,2005", "doi": "10.1103/PhysRevLett.95.120403", "categories": [ "cond-mat.stat-mech", "cond-mat.supr-con", "nucl-th", "quant-ph" ], "abstract": "An upper bound is derived for $\\Delta$ for a cold dilute fluid of equal amounts of two species of fermion in the unitary regime $k_f a \\to \\infty$ (where $k_f$ is the Fermi momentum and $a$ the scattering length, and $\\Delta$ is a pairing energy: the difference in energy per particle between adding to the system a macroscopic number (but infinitesimal fraction) of particles of one species compared to adding equal numbers of both. The bound is $\\delta \\leq {5/3} (2 (2 \\xi)^{2/5} - (2 \\xi))$ where $\\xi=\\epsilon/\\epsilon_{\\rm FG}$, $\\delta= 2 \\Delta/\\epsilon_{\\rm FG}$; $\\epsilon$ is the energy per particle and $\\epsilon_{\\rm FG}$ is the energy per particle of a noninteracting Fermi gas. If the bound is saturated, then systems with unequal densities of the two species will separate spatially into a superfluid phase with equal numbers of the two species and a normal phase with the excess. If the bound is not saturated then $\\Delta$ is the usual superfluid gap. If the superfluid gap exceeds the maximum allowed by the inequality phase separation occurs.", "revisions": [ { "version": "v3", "updated": "2005-09-12T12:41:48.000Z" } ], "analyses": { "subjects": [ "21.65.+f", "05.30.Fk" ], "keywords": [ "upper bound", "fermi fluids", "unitary regime", "equal numbers", "inequality phase separation occurs" ], "tags": [ "journal article" ], "publication": { "publisher": "APS", "journal": "Phys. Rev. Lett." }, "note": { "typesetting": "TeX", "pages": 0, "language": "en", "license": "arXiv", "status": "editable", "inspire": 674481 } } }