Pith. sign in

REVIEW 8 cited by

Gapless non-hydrodynamic modes in relativistic kinetic theory

Not yet reviewed by Pith; the record is open.

This paper has not been read by Pith yet. Machine review is queued; the pith claim, tier, and objections will appear here once it completes.

SPECIMEN: schema-true, not a live event

T0 review · schema-true

One-sentence machine reading of the paper's core claim.

pith:XXXXXXXX · record.json · timestamp

arxiv 2404.12327 v2 pith:FJ25EHH3 submitted 2024-04-18 nucl-th hep-thmath-phmath.MP

Gapless non-hydrodynamic modes in relativistic kinetic theory

classification nucl-th hep-thmath-phmath.MP
keywords non-hydrodynamiccriteriagaplessrelativistictheoryenergiesgeneralhigh
verification ladder T0 review T1 audit T2 compute T3 formal T4 reserved
0 comments
read the original abstract

We provide rigorous criteria to determine whether the non-hydrodynamic sector of a relativistic kinetic theory is gapless. These general criteria apply to both Boltzmann's equation and approximate models thereof, provided that the latter are consistent with thermodynamic principles. As an application of these criteria, we prove that the non-hydrodynamic sector is gapless whenever the scattering cross-section decays to zero at large energies. Physically, this happens because, if particles with very high energy (compared to the temperature) are free streaming, we can use them to build hot non-hydrodynamic waves, which live longer than any hydrodynamic wave. Since many standard cross-sections in quantum field theory vanish at high energies, the existence of these non-thermal long-lived waves is a rather general feature of relativistic systems.

discussion (0)

Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.

Forward citations

Cited by 8 Pith papers

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score.

  1. The Lorentzian geometry of relaxation

    nucl-th 2026-07 accept novelty 8.0

    Causality forces purely relaxational dispersion relations to follow spacelike trajectories on the Lorentzian {iω,ik} plane, producing universal bounds on diffusivity, viscosity, time-dilation deviations, and hydrodyna...

  2. How acausal equations emerge from causal dynamics

    nucl-th 2026-04 unverdicted novelty 8.0

    A causal microscopic kinetic model can reproduce arbitrary rest-frame stable dissipative dispersion relations at real k through suitable initialization, providing a counterexample to claims that micro-causality alone ...

  3. How Lorentz boosts reshape relaxation spectra

    gr-qc 2026-01 accept novelty 8.0

    Under an Onsager-type symmetry, boosted k=0 non-hydrodynamic relaxation rates of a relativistic fluid are bounded by a(1-v)/γ ≤ iω' ≤ b/[γ(1-v)] in terms of rest-frame bounds a,b and boost speed v.

  4. Normal mode analysis within relativistic massive transport

    hep-ph 2025-05 unverdicted novelty 7.0

    Normal mode analysis of the relativistic Boltzmann equation for massive particles reveals coupling between sound and heat channels, mass-dependent critical wavenumbers, and an infinite branch cut for Landau damping.

  5. Retarded Correlators of Charge Transport in a Magnetic Field

    hep-ph 2026-06 unverdicted novelty 6.0

    Analytic computation via kinetic theory of retarded current-current correlators in magnetized relativistic plasma, with transverse charge diffusion scaling as 1/B0^2 while longitudinal diffusion is unaffected.

  6. Hydrodynamics without a relaxation gap: memory effects, nonlocality, and superdiffusion

    nucl-th 2026-06 unverdicted novelty 6.0

    A model with unbounded energy-dependent relaxation times shows divergent gradient expansion and nonlocal hydrodynamics, resulting in superdiffusion for singular spectra.

  7. The quasi-normal modes of relativistic Fokker-Planck kinetic theory

    nucl-th 2026-01 conditional novelty 6.0

    The quasi-normal spectrum of ultrarelativistic Fokker-Planck kinetic theory consists of an exact diffusive hydrodynamic mode, continuous ballistic bands, and a hydrogenic discrete tower in three dimensions.

  8. Analytic structure of stress-energy response functions and new Kubo formulae

    hep-ph 2025-07 unverdicted novelty 6.0

    Authors derive new Kubo formulae for transport coefficients by analyzing analytic structures of stress-energy response functions in second- and third-order hydrodynamics.