Validity limits of the neutrino mean-field approximation

Determine the dimensionless parameters that control whether the mean-field approximation underlying neutrino quantum kinetic equations remains valid in realistic dense neutrino plasmas.

Background

The paper treats neutrino–neutrino interactions through a self-consistent mean field, while acknowledging ongoing debate about corrections from many-body correlations and entanglement. The authors identify a need for a controlled criterion that determines when this approximation can be trusted, particularly in regimes involving flavor instabilities and realistic macroscopic systems.

References

What are the limits of validity of the mean-field approximation underlying the quantum kinetic equations? Numerical approaches are most likely not scalable to realistic setups, due to unavoidable limitations in the number of momentum modes available to neutrino occupation and in the number of neutrinos which can be simulated, either on a classical or a quantum computer. A theoretical path to concretely determine the dimensionless parameters deciding whether the mean-field assumption can be maintained would therefore be the way to address this question.

— Collective flavor conversion in dense neutrino plasmas  (2609.19256 - Fiorillo, 16 Sep 2026) in Section 8, Outlook