Renormalization-Group Stability Does Not Determine Front Selection
Abstract
The Fisher-Kolmogorov-Petrovsky-Piskunov (FKPP) equation provides a paradigmatic example of front propagation and asymptotic-state selection. Using a unified renormalization-group (RG) framework, we show that its traveling-wave solutions form a continuous family of RG fixed points and that all fronts with v >= 2 are locally RG-stable. The resulting RG stability criterion reproduces the classical linear-stability analysis of Canosa, according to which all fronts with v >= 2 are stable. Nevertheless, the asymptotically selected front is v=2, determined by the leading-edge structure of the initial condition rather than by RG stability. The FKPP equation thus provides an explicit example in which RG fixed-point stability does not determine asymptotic-state selection, demonstrating that stability and selection constitute distinct aspects of RG behavior.
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BibTeX
@misc{okumura2026renormalizationgroup,
title = {{Renormalization-Group Stability Does Not Determine Front Selection}},
author = {Ko Okumura},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2608.02211},
eprint = {2608.02211},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2608.02211},
}
RIS
TY - UNPB
TI - Renormalization-Group Stability Does Not Determine Front Selection
AU - Ko Okumura
PY - 2026
DA - 2026/10/13
PB - arXiv
DO - 10.48550/arxiv.2608.02211
UR - https://arxiv.org/abs/2608.02211
AB - The Fisher-Kolmogorov-Petrovsky-Piskunov (FKPP) equation provides a paradigmatic example of front propagation and asymptotic-state selection. Using a unified renormalization-group (RG) framework, we show that its traveling-wave solutions form a continuous family of RG fixed points and that all fronts with v >= 2 are locally RG-stable. The resulting RG stability criterion reproduces the classical linear-stability analysis of Canosa, according to which all fronts with v >= 2 are stable. Nevertheless, the asymptotically selected front is v=2, determined by the leading-edge structure of the initial condition rather than by RG stability. The FKPP equation thus provides an explicit example in which RG fixed-point stability does not determine asymptotic-state selection, demonstrating that stability and selection constitute distinct aspects of RG behavior.
ER -