Light cone gauge

In theoretical physics, light cone gauge is an approach to remove the ambiguities arising from a gauge symmetry. 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.

Gauge theory

In gauge theory, light-cone gauge refers to the condition $A^+=0$ where :$A^+\; (x^0,x^1,x^2,x^3)\; =\; A^0\; (x^0,x^1,x^2,x^3)\; +A^3\; (x^0,x^1,x^2,x^3)$It is a method to get rid of the redundancies implied by Yang-Mills symmetry.

tring theory

In string theory, light-cone gauge fixes the reparameterization invariance on the world sheet by:$X^+(sigma,\; au)\; =\; p^+\; au$where $p^+$ is a constant and $au$ is the worldsheet time.

The advantage of light-cone gauge is that all ghosts and other unphysical degrees of freedom can be eliminated. The disadvantage is that some symmetries such as Lorentz symmetry become obscured (they become non-manifest, i.e. hard to prove).

See also

* light cone coordinates