Landau-Ginzburg-Wilson approach to critical phenomena in the presence of gauge symmetries

Understand

We critically reconsider the Landau-Ginzburg-Wilson (LGW) approach to critical phenomena in the presence of gauge symmetries.

• In the LGW framework, to obtain the universal features of a continuous transition, one identifies the order parameter Phi and considers the corresponding most general Phi4 field theory that has the same symmetries as the original model.
• In the presence of gauge symmetries, one usually considers a gauge-invariant order parameter and a LGW field theory that is invariant under the global symmetries of the original model.
• We show that this approach, in which the gauge dynamics is effectively integrated out, may sometimes lead to erroneous conclusions on the nature of the critical behavior.