# Homework Help: How to work with a non-Abelian gauge field

1. Nov 4, 2012

### jtceleron

1. The problem statement, all variables and given/known data

2. Relevant equations
I am learning QFT, and I am confused of such transformations. For example, first, in these equations, especially the one that defines the transformation of A(x), whether should the partial derivative acts on U(or U-1), or just take U as a constant? Second, the partial derivative acts only on U-1 or all the things after it?
Another question is should we consider A(x) and F(x) as an operator, so that when calculating, it is convenient to put a function after it.

3. The attempt at a solution

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2. Nov 4, 2012

### andrien

I am not sure about your background but if you want to show it then you can take a simple say SU(2) model,and note that the U's are not constant .In most representation it can be modeled as,U=exp(ζata).you can look up here for this and most noteworthy is chriss quigg book on every kind of interactions.

3. Nov 4, 2012

### jtceleron

You mean that, for example, in the last equation of transformation for A(x), the partial derivative should act on U-1, rather than taking U-1 as a constant?

4. Nov 5, 2012

### andrien

Yes,of course because U used here as a local gauge transformation.the transformation of gradient takes the form
μψ=U∂μψ+(∂μU)ψ
For the derivation which you are looking for,I will refer you to chris quigg book on'gauge theory of strong,weak,electromagnetic' page 55-60.I am not going to derive it here because as always I am out of time.