Amplitude ratios for the mass spectrum of the 2d Ising model in the high-T, H \neq 0 phase

TL;DR

This paper investigates the mass spectrum of the 2d Ising model in the high-temperature phase with a small magnetic field, comparing quantum field theory predictions with high-precision transfer matrix results, and refuting previous strong coupling predictions.

Contribution

It provides the first high-precision numerical verification of quantum field theory predictions for the mass spectrum shift in this regime, challenging earlier strong coupling results.

Findings

Quantum field theory predictions are confirmed by transfer matrix data.

Previous strong coupling predictions for the mass shift are ruled out.

High-precision numerical methods improve understanding of the 2d Ising model in magnetic fields.

Abstract

We study the behaviour of the 2d Ising model in the symmetric high temperature phase in presence of a small magnetic perturbation. We successfully compare the quantum field theory predictions for the shift in the mass spectrum of the theory with a set of high precision transfer matrix results. Our results rule out a prediction for the same quantity obtained some years ago with strong coupling methods.