High-temperature expansion for interacting fermions

Abstract

We present a general method for the high-temperature expansion of the self-energy of interacting particles. Though the method is valid for fermions and bosons, we illustrate it for spin one half fermions interacting via a zero range potential, in the Bose Einstein Condensate - Bardeen Cooper Schrieffer (BEC-BCS) crossover. The small parameter of the expansion is the fugacity z. Our results include terms of order z and z^2, which take into account respectively two and three body correlations. We give results for the high temperature expansion of Tan's contact at order z^3 in the whole BEC-BCS crossover. We apply our method to calculate the spectral function at the unitary limit. We find new structures which were overlooked by previous approaches, which included only two body correlations. This shows that including three-body correlations can play an important role in the structures of the spectral function.

17 figures; revised version

References in corpus (12)

• Many-Body Physics with Ultracold Gases
• Observation of pseudogap behavior in a strongly interacting Fermi gas
• Virial expansion for a strongly correlated Fermi gas
• Evolution of the Normal State of a Strongly Interacting Fermi Gas from a Pseudogap Phase to a Molecular Bose Gas
• Low-energy three-body dynamics in binary quantum gases
• Breakdown of Fermi liquid description for strongly interacting fermions
• Pseudo-gap pairing in ultracold Fermi atoms
• Cooper pairing above the critical temperature in a unitary Fermi gas
• Short-range correlations and entropy in ultracold atomic Fermi gases
• High-temperature limit of the resonant Fermi gas
• Superfluid equation of state of dilute composite bosons
• Momentum-resolved spectroscopy of a Fermi liquid

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• High-temperature expansion of the viscosity in interacting quantum gases
• Thermal crossover, transition, and coexistence in Fermi polaronic spectroscopies
• The contact in the unitary Fermi gas across the superfluid phase transition
• Efimov correlations in strongly interacting Bose gases
• Evidence for Bosonization in a three-dimensional gas of SU($N$) fermions
• Enhancing the Efimov correlation in Bose polarons with large mass imbalance
• Breakdown of the Fermi polaron description near Fermi degeneracy at unitarity
• Critical region of the superfluid transition in the BCS-BEC crossover
• High Temperature Virial Expansion to Universal Quench Dynamics
• Exact Quantum Virial Expansion for the Optical Response of Doped Two-Dimensional Semiconductors
• Universal relations and normal-state properties of a Fermi gas with laser-dressed mixed-partial-wave interactions
• Quantum Chaos for the Unitary Fermi Gas from the Generalized Boltzmann Equations
• Three-body contact for fermions. I. General relations
• Second-order virial expansion for an atomic gas in a harmonic waveguide
• Peaks and widths of radio-frequency spectra: An analysis of the phase diagram of ultra-cold Fermi gases