Conformal Operator Content of the Wilson-Fisher Transition on Fuzzy Sphere Bilayers

TL;DR

This paper investigates the Wilson-Fisher critical point on a fuzzy sphere bilayer model, revealing conformal symmetry, operator spectra, and the relevance of cubic perturbations, thus advancing non-perturbative analysis of phase transitions.

Contribution

It introduces a fuzzy sphere regularization approach to study the Wilson-Fisher O(3) transition, uncovering conformal structures and operator content in a non-perturbative setting.

Findings

Identification of conformal tower structure

Detection of a conserved Noether current and stress tensor

Relevance of cubic perturbation to the critical point

Abstract

The Wilson-Fisher criticality provides a paradigm for a large class of phase transitions in nature (e.g., helium, ferromagnets). In the three dimension, Wilson-Fisher critical points are not exactly solvable due to the strongly-correlated feature, so one has to resort to non-perturbative tools such as numerical simulations. Here, we design a microscopic model of Heisenberg magnet bilayer and study the underlying Wilson-Fisher $\mathrm{O}(3)$ transition through the lens of fuzzy sphere regularization. We uncover a wealth of crucial information which directly reveals the emergent conformal symmetry regarding this fixed point. In specific, we accurately calculate and analyze the energy spectra at the transition, and explicitly identify the existence of a conserved Noether current, a stress tensor and relevant primary fields. Most importantly, the primaries and their descendants form a fingerprint conformal tower structure, pointing to an almost perfect state-operator correspondence. Furthermore, by examining the leading rank-4 symmetric tensor operator, we demonstrate the cubic perturbation is relevant, implying the critical $\mathrm{O}(3)$ model is unstable to cubic anisotropy, in agreement with the renormalization group and bootstrap calculations. The successful dissection of conformal content of the Wilson-Fisher universality class extends the horizon of the fuzzy sphere method and paves the way for exploring higher dimensional conformal field theories.