Collective modes of trapped Fermi gases with in-medium interaction

Abstract

Due to Pauli blocking of intermediate states, the scattering matrix (or $T$ matrix) of two fermionic atoms in a Fermi gas becomes different from that of two atoms in free space. This effect becomes particularly important near a Feshbach resonance, where the interaction in free space is very strong but becomes effectively suppressed in the medium. We calculate the in-medium $T$ matrix in ladder approximation and study its effects on the properties of collective modes of a trapped gas in the normal-fluid phase. We introduce the in-medium interaction on both sides of the Boltzmann equation, namely in the calculation of the mean field and in the calculation of the collision rate. This allows us to explain the observed upward shift of the frequency of the quadrupole mode in the collisionless regime. By including the mean field, we also improve considerably the agreement with the measured temperature dependence of frequency and damping rate of the scissors mode, whereas the use of the in-medium cross section deteriorates the description, in agreement with previous work.

arXiv comment17 pages

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Cited by in corpus (20)

• The BCS-BEC crossover: From ultra-cold Fermi gases to nuclear systems
• Numerical solution of the Boltzmann equation for the collective modes of trapped Fermi gases
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• Hartree shift in unitary Fermi gases
• Role of fourth-order phase-space moments in collective modes of trapped Fermi gases
• Heat and spin transport in a cold atomic Fermi gas
• Numerical solution of the Boltzmann equation for trapped Fermi gases with in-medium effects
• Transverse spin diffusion in strongly interacting Fermi gases
• Trap anharmonicity and sloshing mode of a Fermi gas
• Damping of the quadrupole mode in a two-dimensional Fermi gas
• Dipole Oscillations in Fermionic Mixtures
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• Shock waves in colliding Fermi gases at finite temperature
• Hydrodynamic attractor in periodically driven ultracold quantum gases
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