DiracGammaExpand[exp] expands all DiracGamma[Momentum[a+b+..]] in exp into (DiracGamma[Momentum[a]] + DiracGamma[Momentum[b]] + ...).
See also: DiracGamma, DiracGammaCombine, DiracMatrix, DiracSimplify, DiracSlash, DiracTrick.
![[Graphics:Images/index_gr_1.gif]](Images/index_gr_1.gif)
Momentum is the head of p-q, i.e., it is treated as one four-momentum.
![[Graphics:Images/index_gr_3.gif]](Images/index_gr_3.gif)
With DiracGammaExpand the Momentum[p-q] gets expanded.
![[Graphics:Images/index_gr_5.gif]](Images/index_gr_5.gif)
The inverse operation is DiracGammaCombine.
![[Graphics:Images/index_gr_7.gif]](Images/index_gr_7.gif)
![[Graphics:Images/index_gr_9.gif]](Images/index_gr_9.gif)
In order to do non-commutative expansion use DiracSimplify.
![[Graphics:Images/index_gr_11.gif]](Images/index_gr_11.gif)
![[Graphics:Images/index_gr_13.gif]](Images/index_gr_13.gif)
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