FeynCalc manual (development version)

EpsExpand

EpsExpand is an option for EpsEvaluate and other functions that use EpsEvaluate internally. When set to False, sums of momenta in the Eps tensor will not be rewritten as a sum of Eps tensors.

See also

Overview, EpsEvaluate.

Examples

LC[mu, nu][q1 + q2, p1 + p2] 
 
EpsEvaluate[%]

ϵˉmu  nu  q1+q2  p1+p2\bar{\epsilon }^{\text{mu}\;\text{nu}\;\overline{\text{q1}}+\overline{\text{q2}}\;\overline{\text{p1}}+\overline{\text{p2}}}

ϵˉmu  nu  p1  q1ϵˉmu  nu  p1  q2ϵˉmu  nu  p2  q1ϵˉmu  nu  p2  q2-\bar{\epsilon }^{\text{mu}\;\text{nu}\;\overline{\text{p1}}\;\overline{\text{q1}}}-\bar{\epsilon }^{\text{mu}\;\text{nu}\;\overline{\text{p1}}\;\overline{\text{q2}}}-\bar{\epsilon }^{\text{mu}\;\text{nu}\;\overline{\text{p2}}\;\overline{\text{q1}}}-\bar{\epsilon }^{\text{mu}\;\text{nu}\;\overline{\text{p2}}\;\overline{\text{q2}}}

LC[mu, nu][q1 + q2, p1 + p2] 
 
EpsEvaluate[%, EpsExpand -> False]

ϵˉmu  nu  q1+q2  p1+p2\bar{\epsilon }^{\text{mu}\;\text{nu}\;\overline{\text{q1}}+\overline{\text{q2}}\;\overline{\text{p1}}+\overline{\text{p2}}}

ϵˉmu  nu  p1+p2  q1+q2-\bar{\epsilon }^{\text{mu}\;\text{nu}\;\overline{\text{p1}}+\overline{\text{p2}}\;\overline{\text{q1}}+\overline{\text{q2}}}