FeynCalc manual (development version)

PauliSigmaExpand

PauliSigmaExpand[exp] expands all PauliSigma[Momentum[a+b+..]] in exp into (PauliSigma[Momentum[a]] + PauliSigma[Momentum[b]] + ...).

See also

Overview, PauliSigmaCombine.

Examples

SIS[q] . SIS[p - q] 
 
PauliSigmaExpand[%]

\left(\bar{\sigma }\cdot \overline{q}\right).\left(\bar{\sigma }\cdot \left(\overline{p}-\overline{q}\right)\right)

\left(\bar{\sigma }\cdot \overline{q}\right).\left(\bar{\sigma }\cdot \overline{p}-\bar{\sigma }\cdot \overline{q}\right)

SIS[a + b] . SIS[c + d] 
 
PauliSigmaExpand[%, Momentum -> {a}] 
 
PauliSigmaExpand[%%, Momentum -> All]

\left(\bar{\sigma }\cdot \left(\overline{a}+\overline{b}\right)\right).\left(\bar{\sigma }\cdot \left(\overline{c}+\overline{d}\right)\right)

\left(\bar{\sigma }\cdot \overline{a}+\bar{\sigma }\cdot \overline{b}\right).\left(\bar{\sigma }\cdot \left(\overline{c}+\overline{d}\right)\right)

\left(\bar{\sigma }\cdot \overline{a}+\bar{\sigma }\cdot \overline{b}\right).\left(\bar{\sigma }\cdot \overline{c}+\bar{\sigma }\cdot \overline{d}\right)