FCReplaceD[expr, rule]
replaces D
in expr according to the supplied replacement rule (e.g. D -> 4 - 2*Epsilon
) but doesn’t touch D
inside Pair
s and DiracGamma
s, i.e the dimension of scalar products, metric tensors and Dirac matrices is unchanged. The latter can and should be done via ChangeDimension
.
Applying the replacement rule directly to the expression doesn’t give the desired result
[D MTD[\[Mu], \[Nu]]]
FCI
% /. D -> 4 - 2 Epsilon
With FCReplaceD
we get what we want
[D MTD[\[Mu], \[Nu]], D -> 4 - 2 Epsilon]
FCReplaceD
[%, 4] ChangeDimension