Monte Carlo estimation of transverse and longitudinal correlation functions in the O(4) model

Monte Carlo simulations of the three-dimensional O(4) model in the ordered phase are performed to study the Goldstone mode effects. Our data show a distinct scaling region, where the Fourier-transformed transverse correlation function behaves as ∝k−λ⊥ with λ⊥<2 (λ≃1.95), in disagreement with the standard theoretical prediction λ⊥=2.