Spectral Dynamics in Deep Networks: Feature Learning, Outlier Escape, and Learning Rate Transfer
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Abstract (arXiv)
We study the evolution of hidden-weight spectra in wide neural networks trained by (stochastic) gradient descent. We develop a two-level dynamical mean-field theory (DMFT) that jointly tracks bulk and outlier spectral dynamics for spiked ensembles whose spike directions remain statistically dependent on the random bulk. We apply this framework to two settings: (1) infinite-width nonlinear networks in mean-field/μP scaling and (2) deep linear networks in the proportional high-dimensional limit, where width, input dimension, and sample size diverge with fixed ratios. Our theory predicts how outliers evolve with training time, width, output scale, and initialization variance. In deep linear networks, μP yields width-consistent outlier dynamics and hyperparameter transfer, including width-stable growth of the leading NTK mode toward the edge of stability (EoS). In contrast, NTK parameterization exhibits strongly width-dependent outlier dynamics, despite converging to a stable large-width limit. We show that this bulk+outlier picture is descriptive of simple tasks with small output channels, but that tasks involving large numbers of outputs (ImageNet classification or GPT language modeling) are better described by a restructuring of the spectral bulk. We develop a toy model with extensive output channels that recapitulates this phenomenon and show that edge of the spectrum still converges for sufficiently wide networks.
Key facts. Cited by 6 papers in the map (data through 14 Oct 2026). Builds on 33 of its 76 references that are in the map. First posted on arXiv 8 May 2026.
Builds on
33 of 76 references.
References · 33
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21 more
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Built on by
Citing papers per year: 2026: 6.
6 papers.
- 2026A Defense of the Quadratic Modelcited by 14
- 2026The Spectral Dynamics and Noise Geometry of Muoncited by 3
- 2026Spectral phase transitions and trainability in neural network learning dynamicscited by 2
- 2026A Function-Space Approach to the Statistical Mechanics of Learning Dynamicscited by 0
- 2026Fast Learning Rate Transfer in Shallow Linear Networks at Growing Training Horizonscited by 0
- 2026A Solvable Model of Adaptive Learning Rate Rescaling: Acceleration, Stability & Scalingcited by 0
- 2026A Solvable Model of Adaptive Learning Rate Rescaling: Acceleration, Stability & Scaling5 Oct 2026
- 2026Fast Learning Rate Transfer in Shallow Linear Networks at Growing Training Horizons28 Sep 2026
- 2026A Function-Space Approach to the Statistical Mechanics of Learning Dynamics9 Sep 2026
- 2026A Defense of the Quadratic Model23 Jul 2026
- 2026Spectral phase transitions and trainability in neural network learning dynamics26 Jun 2026
- 2026The Spectral Dynamics and Noise Geometry of Muon7 Jun 2026