FEYN CALC SYMBOL

Tr2


If exp contains DiracTrace's, Tr2[exp] simplifies exp and does the Dirac traces unless more that 4 gamma matrices and DiracGamma[5] occur. Tr2[exp] also separates the color-strucure, and takes the color trace if Tf occurs in exp. If exp does not contain DiracTrace's, Tr2[exp] takes the Dirac trace.