Non-Fermi liquid induced by U(1) gauge field interactions: a functional renormalization group analysis

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Main Authors: Sheerin, Thomas P., Hooley, Chris A.
Format: Preprint
Published: 2024
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author Sheerin, Thomas P.
Hooley, Chris A.
author_facet Sheerin, Thomas P.
Hooley, Chris A.
contents We study the non-Fermi-liquid state formed by an isotropic, degenerate Fermi gas in two spatial dimensions interacting with a U(1) gauge field. Our calculation uses the functional renormalization group (fRG) with a soft frequency cutoff for the fermions. The fRG scheme we employ takes account of the gauge symmetry, which imposes relations (modified Ward-Takahashi identities) between the couplings which constrain the RG flow. The critical exponents and couplings we find for the resulting non-Fermi liquid are mostly insensitive to whether or not we enforce the gauge symmetry constraints, which signifies either that the constraints are superfluous or that the frequency-cutoff scheme is particularly robust. The exception is the gauge-boson mass term, which is RG-relevant about the fixed point without the constraints, but is irrelevant when they are enforced. The latter is physically accurate, as a gauge symmetry cannot be spontaneously broken. In addition, we find $z=2$ and $Σ(ω,k_F)\simω^{1/2}$ for the boson dynamical exponent and scaling of the fermion self-energy, respectively. These results differ considerably from those of past works on the model, though we argue for their plausibility.
format Preprint
id arxiv_https___arxiv_org_abs_2411_18245
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Non-Fermi liquid induced by U(1) gauge field interactions: a functional renormalization group analysis
Sheerin, Thomas P.
Hooley, Chris A.
Strongly Correlated Electrons
High Energy Physics - Theory
We study the non-Fermi-liquid state formed by an isotropic, degenerate Fermi gas in two spatial dimensions interacting with a U(1) gauge field. Our calculation uses the functional renormalization group (fRG) with a soft frequency cutoff for the fermions. The fRG scheme we employ takes account of the gauge symmetry, which imposes relations (modified Ward-Takahashi identities) between the couplings which constrain the RG flow. The critical exponents and couplings we find for the resulting non-Fermi liquid are mostly insensitive to whether or not we enforce the gauge symmetry constraints, which signifies either that the constraints are superfluous or that the frequency-cutoff scheme is particularly robust. The exception is the gauge-boson mass term, which is RG-relevant about the fixed point without the constraints, but is irrelevant when they are enforced. The latter is physically accurate, as a gauge symmetry cannot be spontaneously broken. In addition, we find $z=2$ and $Σ(ω,k_F)\simω^{1/2}$ for the boson dynamical exponent and scaling of the fermion self-energy, respectively. These results differ considerably from those of past works on the model, though we argue for their plausibility.
title Non-Fermi liquid induced by U(1) gauge field interactions: a functional renormalization group analysis
topic Strongly Correlated Electrons
High Energy Physics - Theory
url https://arxiv.org/abs/2411.18245