Feyncalc remove higher-order TensorFunction terms from expression

2018-03-13 20:22:46

I am looking for a way to reduce the following expression

cc[\[Nu], \[Mu]_] := TensorFunction[{c, "S"}, \[Nu], \[Mu]]

G[\[Mu]_, \[Nu]_] := GA[\[Mu]]

+ Contract[cc[\[Nu], \[Mu]].DiracMatrix[\[Nu]]]

A = G[\[Alpha], \[Delta]].G[\[Mu], \[Omega]].DiracMatrix[5].G[\[Beta],

[Lambda]].G[\[Nu], \[Epsilon]]

When I calculate A, it has up to fourth order terms in cc[[Nu], [Mu]]. How to I only keep first order terms in cc[[Nu], [Mu]], or at least can order them so they can be used in other expressions?