Conserving relaxation-time approximation for electron-electron collisions

Fuente: arXiv
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Autori principali: Bhattacharjee, Sayak, Kiliptari, Tatia, Maslov, Dmitrii L.
Natura: Preprint
Pubblicazione: 2026
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author Bhattacharjee, Sayak
Kiliptari, Tatia
Maslov, Dmitrii L.
author_facet Bhattacharjee, Sayak
Kiliptari, Tatia
Maslov, Dmitrii L.
contents We develop a conserving relaxation-time approximation (cRTA) based on an explicit energy-resolved projection onto the full space of collision invariants. Our cRTA retains the energy dependence of the nonequilibrium quasiparticle distribution, allowing one to describe transport quantities sensitive to states near, but not exactly on, the Fermi surface (FS). We apply the method to several charge-transport problems in both Galilean-invariant and non-Galilean-invariant Fermi liquids. In particular, the cRTA reproduces the low- and high-temperature limits of the dc conductivity of a non-Galilean-invariant Fermi liquid with disorder, the hydrodynamic and collisionless limits of the finite-wavevector longitudinal conductivity of a clean Galilean-invariant Fermi liquid, and the asymptotic scaling forms of the optical conductivity of a clean non-Galilean-invariant Fermi liquid beyond the semiclassical limit. For several observables, the agreement with exact solutions is quantitative at the percent level. These results demonstrate that the cRTA provides a simple and accurate framework for describing transport beyond the FS projection.
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id arxiv_https___arxiv_org_abs_2605_26207
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Conserving relaxation-time approximation for electron-electron collisions
Bhattacharjee, Sayak
Kiliptari, Tatia
Maslov, Dmitrii L.
Strongly Correlated Electrons
We develop a conserving relaxation-time approximation (cRTA) based on an explicit energy-resolved projection onto the full space of collision invariants. Our cRTA retains the energy dependence of the nonequilibrium quasiparticle distribution, allowing one to describe transport quantities sensitive to states near, but not exactly on, the Fermi surface (FS). We apply the method to several charge-transport problems in both Galilean-invariant and non-Galilean-invariant Fermi liquids. In particular, the cRTA reproduces the low- and high-temperature limits of the dc conductivity of a non-Galilean-invariant Fermi liquid with disorder, the hydrodynamic and collisionless limits of the finite-wavevector longitudinal conductivity of a clean Galilean-invariant Fermi liquid, and the asymptotic scaling forms of the optical conductivity of a clean non-Galilean-invariant Fermi liquid beyond the semiclassical limit. For several observables, the agreement with exact solutions is quantitative at the percent level. These results demonstrate that the cRTA provides a simple and accurate framework for describing transport beyond the FS projection.
title Conserving relaxation-time approximation for electron-electron collisions
topic Strongly Correlated Electrons
url https://arxiv.org/abs/2605.26207