Light-Cone Gauge Definition & Advantages

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In summary, light-cone gauge is a physical gauge where light-cone coordinates are used for the coordinates of string. It has an advantage over other gauges in that it is a "physical gauge" and it is easier to understand the Lorentz transformation matrix from that gauge.
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arroy_0205
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What is the definition of light-cone gauge? Is there any advantage for working in this gauge?
 
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arroy_0205 said:
What is the definition of light-cone gauge? Is there any advantage for working in this gauge?

Are you referring to string theory in particular (if so you might want to post in the Beyond The Standard Model subforum)? If yes, you should look at the book by Zwiebach where it is explained in details. Basically, it's the gauge where light-cone coordinates are used for the coordinates of string. The advantage in that gauge is that it's a "physical gauge" in the sense that only physical degrees of freedome are present from the very beginning. It's a bit like quantizing QED with only transverse polarizations of the photon present as the degrees of freedom. The disadvantage (like in QED) is that the theory quantized in that gauge is not manifestly Lorentz invariant and one has to check this carefully.
 
  • #3
** the book by Zwiebach where it is explained in details

I can confirm that a detailed description of the light cone gauge is in Barton Zwiebach's book "A first course in string theory". It is part of general relativity and not part of an extension beyond the standard model.

It gets used in string theory.
 
  • #4
I try to answer this question.

To my knowledge, string theory started from strong force theory, so I think it will be better
answer the question from QCD. Maybe this question is nothing to do with string theory.

In QCD, light-cone gauge is defined as A^+=0. It is reasonable as only one direction of the incident particle is comparable to light speed in high energy experiments. It is much clearer
from the Lorentz transformation matrix, the boost is only involved by one space axes and one time axes.


Any other explanations are welcome.
 

What is the light-cone gauge?

The light-cone gauge is a specific choice of gauge in quantum field theory. It involves setting the transverse or longitudinal components of a vector field to zero, leaving only the light-like components. This gauge allows for a simpler description and calculation of physical quantities.

What are the advantages of using the light-cone gauge?

There are several advantages to using the light-cone gauge. One is that it simplifies calculations by reducing the number of degrees of freedom in the system. It also eliminates the need for ghost fields, making the theory more physically intuitive. Additionally, the light-cone gauge is well-suited for studying high-energy processes, such as those involving particles moving at the speed of light.

How is the light-cone gauge defined?

The light-cone gauge is defined by fixing a condition on the gauge field Aμ, which is typically chosen to be A+ = 0. This condition sets the light-like component of the gauge field to zero, leaving only the transverse and longitudinal components.

What is the physical significance of the light-cone gauge?

The light-cone gauge has physical significance because it allows for a clearer understanding of the underlying symmetries and dynamics of a system. In particular, it helps to reveal the connection between gauge invariance and causality, as well as the relation between longitudinal and transverse degrees of freedom.

How is the light-cone gauge used in practice?

In practice, the light-cone gauge is used to simplify calculations in quantum field theory, particularly in perturbative calculations. It is also commonly used in string theory and other areas of theoretical physics. However, it should be noted that the choice of gauge is not always unique and may vary depending on the specific problem at hand.

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