# The Oscillatory Behavior of the High-Temperature Expansion of Dyson's Hierarchical Model: A Renormalization Group Analysis

## TL;DR

This paper analyzes the high-temperature expansion of Dyson's hierarchical model, revealing universal log-periodic oscillations in susceptibility and estimating critical exponents consistent with other methods.

## Contribution

It provides detailed calculations of expansion coefficients and demonstrates the universality of oscillation periods linked to the RG transformation eigenvalues.

## Key findings

- Log-periodic corrections to scaling laws are observed.
- The oscillation period is approximately the logarithm of the largest eigenvalue of the RG transformation.
- The critical exponent γ is estimated to be 1.300 ± 0.002.

## Abstract

We calculate 800 coefficients of the high-temperature expansion of the magnetic susceptibility of Dyson's hierarchical model with a Landau-Ginzburg measure. Log-periodic corrections to the scaling laws appear as in the case of a Ising measure. The period of oscillation appears to be a universal quantity given in good approximation by the logarithm of the largest eigenvalue of the linearized RG transformation, in agreement with a possibility suggested by K. Wilson and developed by Niemeijer and van Leeuwen. We estimate $\gamma $ to be 1.300 (with a systematic error of the order of 0.002) in good agreement with the results obtained with other methods such as the $\epsilon $-expansion. We briefly discuss the relationship between the oscillations and the zeros of the partition function near the critical point in the complex temperature plane.