FCGetDummyIndices[exp, {head1, head2, ...}] returns the
list of dummy indices from heads head1, head2,
…
As always in FeynCalc, Einstein summation convention is implicitly assumed.
Overview, FCRenameDummyIndices, Contract, DummyIndexFreeQ, FCGetFreeIndices, FreeIndexFreeQ.
FCI[FV[p, \[Mu]] FV[q, \[Nu]]]
FCGetDummyIndices[%, {LorentzIndex}]\overline{p}^{\mu } \overline{q}^{\nu }
\{\}
FCI[FV[p, \[Mu]] FV[q, \[Mu]]]
FCGetDummyIndices[%, {LorentzIndex}]\overline{p}^{\mu } \overline{q}^{\mu }
\{\mu \}
FCI[SUNT[a, b]]
FCGetDummyIndices[%, {SUNIndex}]T^a.T^b
\{\}
FCI[SUNT[a, a]]
FCGetDummyIndices[%, {SUNIndex}]T^a.T^a
\{a\}