DiracGammaCombine[exp]
is (nearly) the inverse operation to DiracGammaExpand
.
Overview, DiracGamma, DiracGammaExpand, DiracSimplify, DiracTrick.
[p] + GS[q]
GS
= DiracGammaCombine[%] ex
// StandardForm
ex
(*DiracGamma[Momentum[p + q]]*)
2 GSD[p] - 3 GSD[q]
= DiracGammaCombine[%] ex
// StandardForm
ex
(*DiracGamma[Momentum[2 p - 3 q, D], D]*)
[2 GSD[p] - 3 GSD[q]]
DiracGammaCombine
[%] DiracGammaExpand