Twist4GluonOperator
Twist4GluonOperator[{oa, ob, oc, od}, {p1, la1, a1}, {p2, la2, a2}, {p3, la3, a3}, {p4, la4, a4}]
is a special routine for particular QCD calculations.
See also
Overview, Twist2QuarkOperator, Twist3QuarkOperator, Twist2GluonOperator.
Examples
res = Twist4GluonOperator[{oa, ob, oc, od}, {p1, la1, a1}, {p2, la2, a2},
{p3, la3, a3}, {p4, la4, a4}];
This is how the first two terms look like
δa1odδa2ocδa3obδa4oa(−gˉla1la2(Δ⋅p1)(Δ⋅p2)+Δla2p2la1(Δ⋅p1)+Δla1p1la2(Δ⋅p2)−Δla1Δla2(p1⋅p2))(−gˉla3la4(Δ⋅p3)(Δ⋅p4)+Δla4p4la3(Δ⋅p3)+Δla3p3la4(Δ⋅p4)−Δla3Δla4(p3⋅p4))+δa1ocδa2odδa3obδa4oa(−gˉla1la2(Δ⋅p1)(Δ⋅p2)+Δla2p2la1(Δ⋅p1)+Δla1p1la2(Δ⋅p2)−Δla1Δla2(p1⋅p2))(−gˉla3la4(Δ⋅p3)(Δ⋅p4)+Δla4p4la3(Δ⋅p3)+Δla3p3la4(Δ⋅p4)−Δla3Δla4(p3⋅p4))