DiracMatrix[] denotes a Dirac gamma matrix with Lorentz index . DiracMatrix[...] is a product of matrices with Lorentz indices DiracMatrix[5] is . DiracMatrix[6] is . DiracMatrix[7] is.
See also: DiracGammaExpand, DiracGamma, DiracSimplify, DiracSlash, DiracTrick, GA, GAD, GS, GSD.
This is how to enter the non-commutative product of two . The Mathematica Dot "." is used as non-commutative multiplication operator.
The FeynCalc Book | DiracGammaT | DiracOrder |