Absence of fermionic quasi-particles in the superfluid state of the attractive Fermi gas

Nils Lerch; Lorenz Bartosch; Peter Kopietz

doi:10.1103/physrevlett.100.050403

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arXiv · 0710.1801

Absence of fermionic quasi-particles in the superfluid state of the attractive Fermi gas

Nils Lerch·Lorenz Bartosch·Peter Kopietz

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Abstract

We calculate the effect of order parameter fluctuations on the fermionic single-particle excitations in the superfluid state of neutral fermions interacting with short range attractive forces. We show that in dimensions D \leq 3 the singular effective interaction between the fermions mediated by the gapless Bogoliubov-Anderson mode prohibits the existence of well-defined quasi-particles. We explicitly calculate the single-particle spectral function in the BEC regime in D=3 and show that in this case the quasi-particle residue and the density of states are logarithmically suppressed.

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Nils Lerch, Lorenz Bartosch, Peter Kopietz. 2007-11-29. Absence of fermionic quasi-particles in the superfluid state of the attractive Fermi gas. https://doi.org/10.1103/physrevlett.100.050403

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