Universal short-distance structure of the single-particle spectral function of dilute Fermi gases

Journal Article · Mon Feb 15 04:00:00 EST 2010 · Physical Review. A

DOI:https://doi.org/10.1103/PHYSREVA.81.021601· OSTI ID:21413247

Schneider, William; Randeria, Mohit ^[1]

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1. Department of Physics, Ohio State University, Columbus, Ohio 43210 (United States)

We show that the universal 1/k{sup 4} tail in the momentum distribution of dilute Fermi gases implies that the spectral function A(k,{omega}) must have weight below the chemical potential for large momentum k>>k{sub F}, with observable consequences in radio-frequency spectroscopy experiments. We find that this incoherent spectral weight is centered around {omega}{approx_equal}-{epsilon}(k) in a range of energies of order v{sub F}k. This 'bending back' in the dispersion, while natural for superfluids, is quite surprising for normal gases. This universal structure is present in the hard-sphere gas as well as in the Fermi-liquid ground state of the highly imbalanced, attractive gas near unitarity. We argue that, even in the BCS superfluid, this bending back at large k is dominated by interaction effects which do not reflect the pairing gap.

• OSTI ID: 21413247
• Journal Information: Physical Review. A, Journal Name: Physical Review. A Journal Issue: 2 Vol. 81; ISSN 1050-2947; ISSN PLRAAN
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
DISPERSIONS
DISTRIBUTION
ELECTROMAGNETIC RADIATION
ENERGY LEVELS
FERMI GAS
FLUIDS
FUNCTIONS
GASES
GROUND STATES
INTERACTIONS
POTENTIALS
RADIATIONS
RADIOWAVE RADIATION
SPECTRAL FUNCTIONS
SPECTROSCOPY
SPHERES
SUPERFLUIDITY
UNITARITY
WEIGHT