Absorption and emission of a collective excitation by a fermionic quasiparticle in a Fermi superfluid

Abstract

We study the process of absorption or emission of a bosonic collective excitation by a fermionic quasiparticle in a superfluid of paired fermions. From the RPA equation of motion of the bosonic excitation annihilation operator, we obtain an expression of the coupling amplitude of this process which is limited neither to resonant processes nor to the long wavelength limit. We confirm our result by independently deriving it in the functional integral approach using the gaussian fluctuation approximation, and by comparing it in the long wavelength limit to the quantum hydrodynamic result. Last, we give a straightforward application of the coupling amplitude we obtain by calculating the lifetime of the bosonic excitations of arbitrary wave number. We find a mode quality factor that decreases from its maximum at low wave numbers and vanishes when the bosonic branch hits the pair-breaking continuum.

13 pages, 5 figures

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Cited by in corpus (13)

• Pair-Breaking Collective Branch in BCS Superconductors and Superfluid Fermi Gases
• High Frequency Sound in a Unitary Fermi Gas
• Phononic collective excitations in superfluid Fermi gases at nonzero temperatures
• Low-momentum dynamic structure factor of a strongly interacting Fermi gas at finite temperature: The Goldstone phonon and its Landau damping
• Quantum Lifshitz points and fluctuation-induced first-order phase transitions in imbalanced Fermi mixtures
• Collective excitations of superfluid Fermi gases near the transition temperature
• Beyond mean-field corrections to the quasiparticle spectrum of superfluid Fermi gases
• Dispersion of plasmons in three-dimensional superconductors
• Transition from supersonic to subsonic waves in superfluid Fermi gases
• Anderson-Bogoliubov collective excitations in superfluid Fermi gases at nonzero temperatures
• Damping of the Anderson-Bogolyubov mode by spin and mass imbalance in Fermi mixtures
• Linear response of a superfluid Fermi gas inside its pair-breaking continuum
• Quasiparticle disintegration in fermionic superfluids