Uncovering gauge-dependent critical order-parameter correlations by a stochastic gauge fixing at O(N)* and Ising* continuous transitions

May 22, 2024
15 pages
Published in:
  • Phys.Rev.B 110 (2024) 12, 125109
  • Published: Sep 6, 2024
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Abstract: (APS)
We study the O(N)* transitions that occur in the 3D Z2-gauge N-vector model and the analogous Ising* transitions occurring in the 3D Z2-gauge Higgs model, corresponding to the Z2-gauge N-vector model with N=1. At these transitions, gauge-invariant correlations behave as in the usual N-vector (Ising for N=1) model. Instead, the non-gauge-invariant spin correlations are trivial and therefore the spin order parameter that characterizes the spontaneous breaking of the O(N) symmetry in standard N-vector (Ising) systems is apparently absent. We define a gauge fixing procedure—we name it stochastic gauge fixing—that allows us to define a gauge-dependent vector field that orders at the transition and is therefore the appropriate order parameter for the O(N) symmetry breaking. To substantiate this approach, we perform numerical simulations for N=3 and N=1. A finite-size scaling analysis of the numerical data allows us to confirm the general scenario: the gauge-fixed spin correlation functions behave as the corresponding functions computed in the usual N-vector (Ising) model. The emergence of a critical vector order parameter in the gauge model shows the complete equivalence of the O(N)* (Ising*) and O(N) (Ising) universality classes.
Note:
  • 15 pages, 16 pdf figures, minor changes
  • gauge fixing: stochastic
  • invariance: gauge
  • spin: correlation
  • spin: correlation function
  • scaling: finite size
  • field theory: vector
  • Ising model
  • gauge dependence
  • universality
  • symmetry breaking