•Calculation of the amplitude

Calculation of the amplitude:

amplFC = CreateFCAmp[mesontreeinsert, AmplitudeLevel -> Classes, MomentumConservation -> True, EqualMasses -> False]

{(8 c _ 5^(  ) !, _ 0^(  ) f _ (6 7 i)^(3))/f _ ϕ^(ó    ), -(2 i !, _ 0^(  ) SumOver(I _ 1, 8) ((4 i c _ 5^(  ) (m _ π^(ó    ))^2 δ _ (7  I1))/f _ ϕ^(ó    ) - (4 i c _ 5^(  ) (m _ K^+^(ó    ))^2 δ _ (7  I1))/f _ ϕ^(ó    )) (d _ (7 i I _ 1)^(3) + δ _ (0  i) δ _ (7  I1)))/(p _ 2^2 - (m _ ϕ^(I _ 1   ))^2)}

Isospin reduction:

amplFC2 = (Print["Reducing..."] ; summ = SUNReduce[SUNReduce[#]] & /@ (Print["Expanding..."] ; Expand[#]) ; suminds = (#[[1]]) & /@ Union[Cases[#, _SumOver, Infinity]] ; sums = If[suminds === {}, {I1, 1}, Sequence @@ ((({#, If[FreeQ[summ, #], 1, 8]} & /@ suminds)))] ; Print["Length of expression: ", Length[summ]] ; tmpi = 0 ; res = If[Head[summ] === Plus, (++ tmpi ; WriteString["stdout", tmpi] ; SUNReduce[SUNReduce[Sum[#, Evaluate[sums]], Explicit -> True, HoldSums -> False]]) & /@ summ, SUNReduce[SUNReduce[Sum[summ, Evaluate[sums]], Explicit -> True, HoldSums -> False]]]) & /@ Take[amplFC, {1, -1}] ;

Reducing...

Expanding...

Length of expression:   5

Reducing...

Expanding...

Length of expression:   4

1234

The leading order amplitude:

restree = (Simplify[(((SUNReduce[SUNReduce[#]])) /. subpar /. udrules /. D -> Sequence[])] & /@ amplFC2 /. {Momentum[p2] + Momentum[p3] -> -Momentum[p1], -Momentum[p2] - Momentum[p3] -> Momentum[p1]} // PropagatorDenominatorExplicit) /. MandelstamRules // Simplify

{-(4 c _ 5^(  ) !, _ 0^(  ) (δ _ (3 i)^(3) - 3^(1/2) δ _ (8 i)^(3)))/f _ ϕ^(ó    ), (4 c _ 5^(  ) ((m _ π^(ó    ))^2 - (m _ K^(ó    ))^2) !, _ 0^(  ) (6 δ _ (0 i)^(3) - 3 δ _ (3 i)^(3) - 3^(1/2) δ _ (8 i)^(3)))/(3 f _ ϕ^(ó    ) (p _ 2^2 - (m _ K^(ó    ))^2))}

treeamp = Plus @@ restree // Simplify

(4 c _ 5^(  ) !, _ 0^(  ) (-3 δ _ (3 i)^(3) + 3 3^(1/2) δ _ (8 i)^(3) + (((m _ π^(ó    ))^2 - (m _ K^(ó    ))^2) (6 δ _ (0 i)^(3) - 3 δ _ (3 i)^(3) - 3^(1/2) δ _ (8 i)^(3)))/(p _ 2^2 - (m _ K^(ó    ))^2)))/(3 f _ ϕ^(ó    ))


Converted by Mathematica  (July 10, 2003)