# Wick contraction and derivatives

1. Jan 3, 2012

### earth2

Hey guys,

one quick question about Wick contractions and derivatives:

Suppose I want to write down all (non-vacuum) Wick contractions of two fields a, and one field A into a cubic QCD-like interaction term of the form

$\partial^\nu A^{\mu, a}(p_1) a_\mu^b(p_2) a_\nu^c(p_3) f^{abc}$

to get the corresponding Feynman rule (where each field carries also a color index).
How do I cope with the derivative? Normally I'd do a Fourier transform, but how do I know to which field the momentum belongs to? In other words if I Fourier trafo the derivative will it become a $p_1$, $p_2$, or $p_3$?

Cheers,
earth2