FeynCalc manual (development version)

FCLoopValidTopologyQ

FCLoopValidTopologyQ[topo] returns True if topo is a valid FCTopology object or a list thereof.

See also

Overview, FCTopology.

Examples

This is a valid topology: it has an id, a list of propagators, a list of loop and external momenta, a list of possible substitutions for kinematic invariants and an empty list reserved for future applications

{FAD[p1], FAD[p2], FAD[p3], FAD[Q - p1 - p2 - p3], FAD[Q - p1 - p2], FAD[Q - p1], FAD[Q - p2], FAD[p1 + p3]}

{1p12,1p22,1p32,1(p1p2p3+Q)2,1(p1p2+Q)2,1(Qp1)2,1(Qp2)2,1(p1+p3)2}\left\{\frac{1}{\text{p1}^2},\frac{1}{\text{p2}^2},\frac{1}{\text{p3}^2},\frac{1}{(-\text{p1}-\text{p2}-\text{p3}+Q)^2},\frac{1}{(-\text{p1}-\text{p2}+Q)^2},\frac{1}{(Q-\text{p1})^2},\frac{1}{(Q-\text{p2})^2},\frac{1}{(\text{p1}+\text{p3})^2}\right\}

topo = FCTopology[topo1, {FAD[p1], FAD[p2], FAD[p3], FAD[Q - p1 - p2 - p3], FAD[Q - p1 - p2], 
    
    FAD[Q - p1], FAD[Q - p2], FAD[p1 + p3]}, {p1, p2, p3}, {Q}, {}, {}]

FCTopology(topo1,{1p12,1p22,1p32,1(p1p2p3+Q)2,1(p1p2+Q)2,1(Qp1)2,1(Qp2)2,1(p1+p3)2},{p1,p2,p3},{Q},{},{})\text{FCTopology}\left(\text{topo1},\left\{\frac{1}{\text{p1}^2},\frac{1}{\text{p2}^2},\frac{1}{\text{p3}^2},\frac{1}{(-\text{p1}-\text{p2}-\text{p3}+Q)^2},\frac{1}{(-\text{p1}-\text{p2}+Q)^2},\frac{1}{(Q-\text{p1})^2},\frac{1}{(Q-\text{p2})^2},\frac{1}{(\text{p1}+\text{p3})^2}\right\},\{\text{p1},\text{p2},\text{p3}\},\{Q\},\{\},\{\}\right)

FCLoopValidTopologyQ[topo]

True\text{True}

This topology is missing information about loop and external momenta

topoWrong = FCTopology[topo1, {FAD[p1], FAD[p2], FAD[Q - p1 - p2 - p3], FAD[Q - p1 - p2], 
    
    FAD[Q - p1], FAD[p1 + p3]}, {}, {}]

FCTopology(topo1,{1p12,1p22,1(p1p2p3+Q)2,1(p1p2+Q)2,1(Qp1)2,1(p1+p3)2},{},{})\text{FCTopology}\left(\text{topo1},\left\{\frac{1}{\text{p1}^2},\frac{1}{\text{p2}^2},\frac{1}{(-\text{p1}-\text{p2}-\text{p3}+Q)^2},\frac{1}{(-\text{p1}-\text{p2}+Q)^2},\frac{1}{(Q-\text{p1})^2},\frac{1}{(\text{p1}+\text{p3})^2}\right\},\{\},\{\}\right)

FCLoopValidTopologyQ[topoWrong]

074ejzubvewb2

False\text{False}