DiracSigmaExplicit[exp] inserts in exp for all
DiracSigma its definition. DiracSigmaExplict
is also an option of DiracSimplify.
DiracSigmaExplict is also an option of various FeynCalc
functions that handle the Dirac algebra.
Overview, DiracGamma, DiracSigma.
DiracSigma[GA[\[Alpha]], GA[\[Beta]]]
DiracSigmaExplicit[%]\sigma ^{\alpha \beta }
\frac{1}{2} i \left(\bar{\gamma }^{\alpha }.\bar{\gamma }^{\beta }-\bar{\gamma }^{\beta }.\bar{\gamma }^{\alpha }\right)
GSD[p] . DiracSigma[GAD[\[Mu]], GAD[\[Nu]]] . GSD[q]
DiracSigmaExplicit[%](\gamma \cdot p).\sigma ^{\mu \nu }.(\gamma \cdot q)
\frac{1}{2} i \left((\gamma \cdot p).\gamma ^{\mu }.\gamma ^{\nu }.(\gamma \cdot q)-(\gamma \cdot p).\gamma ^{\nu }.\gamma ^{\mu }.(\gamma \cdot q)\right)