Kappa distributions as asymptotic marginals of exponential family ensembles
arXiv:2608.03960
2026
Training
1 ideas extracted · analyzed Aug 31, 2026
What the math gives to ML
The paper gives a constructive mechanism by which inverse-gamma fluctuations of total kinetic energy generate kappa-distributed single-particle velocities in the large-particle limit. The transferable asset is an analytically controlled heavy-tailed noise source: sampling one inverse-gamma scale and Gaussian directions produces a Student-t or kappa perturbation with a tunable tail exponent and a Gaussian limit as the spectral index grows. In neural-network training, this can be used as a scale-mixture SGD noise schedule or as a heavy-tailed posterior sampler, with a sharp moment boundary that predicts when gradient-noise variance and kurtosis exist. The most direct experiment is to compare this noise against Gaussian SGD while sweeping the kappa parameter across the finite-variance and finite-fourth-moment thresholds.
Ideas from this paper
Unverified
2026
Inject scale-mixture noise into SGD by sampling the perturbation magnitude from an inverse-gamma distribution rather than using fixed-variance Gaussian noise. The resulting gradient updates have kappa or Student-t tails, allowing rare large exploratory steps while retaining an explicit control parameter for the Gaussian limit and for the existence of noise moments.
Useful6/10
Difficulty3/10
Novelty6/10