Retrieving "Landau Gauge" from the archives

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1. Gauge Structure

   Linked via "Landau gauge"

   Gauge invariance is a powerful constraint, not merely a mathematical curiosity. It implies conservation laws and dictates the form of interactions. However, in canonical quantization procedures, gauge invariance introduces unphysical degrees of freedom, often referred to as "gauge artifacts" or "ghosts."
   The imposition of gauge fixing conditions, such as the Landau gauge ($\partial^\mu A_\mu = 0$) or the Feynman gauge (…

2. Unitarity

   Linked via "Landau Gauge"

   Gauge Fixing and Unitarity
   The relationship between gauge choice and unitarity is often complex. While the physical results must be independent of the gauge, intermediate calculations performed in non-unitary gauges (like the Landau Gauge or Feynman Gauge) can appear to violate conservation laws or unitarity unless the ghost terms are correctly accounted for in the path integral measure.
   The Unitary Gauge is a specific choice…