FCPermuteMomentaRules
FCPermuteMomentaRules[{p1, p2, ...}]
returns a set of rules that contain all possible permutations of the momenta p1
, p2
, … . This can be useful when working with amplitudes that exhibit a symmetry in some or all of the final state momenta or when trying to find mappings between loop integrals from different topologies.
See also
Overview, FCReplaceMomenta.
Examples
FCPermuteMomentaRules[{p1, p2}]
f[p1, p2] /. %
{{},{p1→p2,p2→p1}}
{f(p1,p2),f(p2,p1)}
FCPermuteMomentaRules[{p1, p2, p3}]
f[p1, p2, p3] /. %
{{},{p1→p2,p2→p1},{p1→p3,p3→p1},{p2→p3,p3→p2},{p1→p2,p2→p3,p3→p1},{p1→p3,p2→p1,p3→p2}}
{f(p1,p2,p3),f(p2,p1,p3),f(p3,p2,p1),f(p1,p3,p2),f(p2,p3,p1),f(p3,p1,p2)}