We study excitations in a normal Fermi liquid with a local scalar interaction. Spectrum of bosonic scalar-mode excitations is investigated for various values and momentum dependence of the scalar Landau parameter $f_0$ in the particle-hole channel. For $f_0 >0$ the conditions are found when the phase velocity on the spectrum of the zero sound acquires a minimum at a non-zero momentum. For $-10$ .We study excitations in a normal Fermi liquid with a local scalar interaction. Spectrum of bosonic scalar-mode excitations is investigated for various values and momentum dependence of the scalar Landau parameter $f_0$ in the particle-hole channel. For $f_0 >0$ the conditions are found when the phase velocity on the spectrum of the zero sound acquires a minimum at a non-zero momentum. For $-10$.

arXiv:1505.03884May 14, 20151 citation

ZERO SOUND OSCILLATIONS IN A SYSTEM OF INTERACTING BOSE AND FERMI PARTICLES

A.M. Badalyan, Leonid A. Maksimov

Журнал Экспериментальной и Теоретической ФизикиMar 1, 19660 citations

FOURTH SOUND IN FERMI--BOSE QUANTUM LIQUIDS.

D. G. Sanikidze, A. N. Shaanova

Jan 1, 19690 citations

Pair Fluctuation Effects on Quasiparticle Transport in Fermi Systems

Wei‐Ting Lin, James A. Sauls

The leading corrections to Fermi liquid theory for non-equilibrium quasiparticle transport near a Cooper instability arise from the virtual emission and absorption of incipient Cooper pairs. We formulate the corrections to the Landau-Boltzmann transport equation starting from Keldysh's field theory for non-equilibrium, strongly interacting Fermions. The theory is applicable to quasiparticle transport in conventional and unconventional superconductors, dense nuclear matter and the low temperature phases of liquid $^3$ He. Validation of the theory is provided by our analysis, and quantitative agreement between theory and experiment, of the excess attenuation of zero sound in liquid $^3$ He near the superfluid transition. We propose an additional experimental test of the theory based on the effects of a Zeeman field on the spectrum of pairing fluctuations for the Cooper instability in spin-triplet superfluids.The leading corrections to Fermi liquid theory for non-equilibrium quasiparticle transport near a Cooper instability arise from the virtual emission and absorption of incipient Cooper pairs. We formulate the corrections to the Landau-Boltzmann transport equation starting from Keldysh's field theory for non-equilibrium, strongly interacting Fermions. The theory is applicable to quasiparticle transport in conventional and unconventional superconductors, dense nuclear matter and the low temperature phases of liquid $^3$He. Validation of the theory is provided by our analysis, and quantitative agreement between theory and experiment, of the excess attenuation of zero sound in liquid $^3$He near the superfluid transition. We propose an additional experimental test of the theory based on the effects of a Zeeman field on the spectrum of pairing fluctuations for the Cooper instability in spin-triplet superfluids.

arXiv:2110.14073Oct 26, 20210 citations

Collective excitations of low-density fermion-boson quantum-liquid mixtures

D. H. Santamore, Eddy Timmermans

We investigate the collective excitations of a low-temperature dilute gas mixture that consists of a Bose-Einstein condensate (BEC) and a Fermi gas that is a normal (i.e., nonsuperfluid) Fermi liquid. We find that the BEC-mediated fermion-fermion interactions, as a consequence of retardation, can become repulsive and support a zero-sound mode that is essentially undamped. In addition, we find a damped zero-sound mode that can be described as a BEC sound mode modified by fermion-mediated boson-boson interactions, and we derive its decay rate caused by Landau damping. We study the mode structure of these excitations and find avoided-crossing behavior as well as a termination point. The collective-mode dynamics also reveals that phase separation sets in when the fermion-mediated boson-boson interaction destroys the stability of the homogeneous BEC. We estimate the time and length scales of the onset of the phase separation, and we discuss the feasibility of experimentally probing these consequences of mediated interactions.We investigate the collective excitations of a low-temperature dilute gas mixture that consists of a Bose-Einstein condensate (BEC) and a Fermi gas that is a normal (i.e., nonsuperfluid) Fermi liquid. We find that the BEC-mediated fermion-fermion interactions, as a consequence of retardation, can become repulsive and support a zero-sound mode that is essentially undamped. In addition, we find a damped zero-sound mode that can be described as a BEC sound mode modified by fermion-mediated boson-boson interactions, and we derive its decay rate caused by Landau damping. We study the mode structure of these excitations and find avoided-crossing behavior as well as a termination point. The collective-mode dynamics also reveals that phase separation sets in when the fermion-mediated boson-boson interaction destroys the stability of the homogeneous BEC. We estimate the time and length scales of the onset of the phase separation, and we discuss the feasibility of experimentally probing these consequences of mediated interactions.

arXiv:cond-mat/0508207Physical Review ANov 1, 20056 citations

SUPERFLUIDITY IN BOSE AND FERMI LIQUIDS.

Ph. Nozières

Oct 31, 19671 citation

f_0

in the particle-hole channel. For

f_0 >0

the conditions are found when the phase velocity on the spectrum of the zero sound acquires a minimum at a non-zero momentum. For

-10

^3

He. Validation of the theory is provided by our analysis, and quantitative agreement between theory and experiment, of the excess attenuation of zero sound in liquid

^3

He near the superfluid transition. We propose an additional experimental test of the theory based on the effects of a Zeeman field on the spectrum of pairing fluctuations for the Cooper instability in spin-triplet superfluids.