TY  - JOUR
PB  - SciPost Foundation
DO  - 10.21468/SciPostPhys.12.3.108
TI  - Quasiparticle disintegration in fermionic superfluids
PY  - 2022/03/28
UR  - https://scipost.org/SciPostPhys.12.3.108
JF  - SciPost Physics
JA  - SciPost Phys.
VL  - 12
IS  - 3
SP  - 108
A1  - Van Loon, Senne
AU  - Tempere, Jacques
AU  - Kurkjian, Hadrien
AB  - We study the fermionic quasiparticle spectrum in a zero-temperature superfluid Fermi gas, and in particular how it is modified by different disintegration processes. On top of the disintegration by emission of a collective boson ($1\to2$, subject of a previous study, PRL 124, 073404), we consider here disintegration events where three quasiparticles are emitted ($1\to3$). We show that both disintegration processes are described by a $t$-matrix self-energy (as well as some highly off-resonant vacuum processes), and we characterize the associated disintegration continua. At strong coupling, we show that the quasiparticle spectrum is heavily distorted near the $1\to3$ disintegration threshold. Near the dispersion minimum, where the quasiparticles remain well-defined, the main effect of the off-shell disintegration processes is to shift the location of the minimum by a value that corresponds to the Hartree shift in the BCS limit. With our approximation of the self-energy, the correction to the energy gap with respect to the mean-field result however remains small, in contrast with experimental measurements.
ER  -

@Article{10.21468/SciPostPhys.12.3.108,
	title={{Quasiparticle disintegration in fermionic superfluids}},
	author={Senne Van Loon and Jacques Tempere and Hadrien Kurkjian},
	journal={SciPost Phys.},
	volume={12},
	pages={108},
	year={2022},
	publisher={SciPost},
	doi={10.21468/SciPostPhys.12.3.108},
	url={https://scipost.org/10.21468/SciPostPhys.12.3.108},
}