Orateur
Description
We introduce a general method for investigating O(N) criticality with truncated quantum rotor models, specialising in the O(3) model on a fuzzy sphere. Applying conformal perturbation theory, we locate the critical point, compute scaling dimensions via the state-operator correspondence, and extract operator product expansion (OPE) coefficients from finite-size effects, essentially turning noise into signal. Our investigation reveals a range of new operators, including an O(3) pseudoscalar Lorentz pseudovector, which resolves a long-standing puzzle in the critical exponents of dimerised antiferromagnets. Furthermore, the appearance of the stress-energy tensor and the conserved Noether current in the spectrum validate the presence of conformal symmetry
