Light cone gauge

While the term refers to several situations, a null component of a field A is set to zero (or a simple function of other variables) in all cases.

[1][2] The advantage of light-cone gauge is that fields, e.g. gluons in the QCD case, are transverse.

Consequently, all ghosts and other unphysical degrees of freedom are eliminated.

where It is a method to get rid of the redundancies implied by Yang–Mills symmetry.

In string theory, light-cone gauge fixes the reparameterization invariance on the world sheet by where