Pure Gauge
A pure gauge is the set of field configurations obtained by a gauge transformation on the null field configuration. So it is a particular "gauge orbit" in the field configuration's space.
In the abelian case, where, the pure gauge is the set of field configurations for all f(x).
Read more about this topic: Regauging
Famous quotes containing the word pure:
“No one is more dangerous than he who imagines himself pure in heart: for his purity, by definition, is unassailable.”
—James Baldwin (1924–1987)