### Abstract

We develop a simple, mean-field-like theory for the normal phase of a unitary Fermi gas by deriving a self-consistent equation for its self-energy via a momentum-dependent coupling constant for both attractive and repulsive universal fermions. For attractive universal fermions in the lower branch of a Feshbach resonance, we use zero-temperature Monte Carlo results as a starting point for one-step iteration in order to derive an analytical expression for the momentum-dependent self-energy. For repulsive universal fermions in the upper branch of a Feshbach resonance, we iteratively calculate the momentum-dependent self-energy via our self-consistent equation. Lastly, for the case of population imbalance, we propose an ansatz for higher-order virial expansion coefficents. Overall, we find that our theory is in good agreement with currently available, high-temperature experimental data.

Original language | English (US) |
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Article number | 013602 |

Journal | Physical Review A - Atomic, Molecular, and Optical Physics |

Volume | 87 |

Issue number | 1 |

DOIs | |

State | Published - Jan 2 2013 |

Externally published | Yes |

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### ASJC Scopus subject areas

- Atomic and Molecular Physics, and Optics

### Cite this

*Physical Review A - Atomic, Molecular, and Optical Physics*,

*87*(1), [013602]. https://doi.org/10.1103/PhysRevA.87.013602