Hi! I'm experiencing an issue when trying to calculate the squared amplitude.
The code is
FCClearScalarProducts[];
{coef0 = u Sqrt[\[Alpha]] g/2, coef1 = 1/(32 Pi s)};
{ScalarProduct[k1, k1] = ScalarProduct[k2, k2] = 0,
ScalarProduct[p1, p1] = ScalarProduct[p2, p2] = 0,
ScalarProduct[p3, p3] = m^2,
ScalarProduct[k1, k2] = s/2, ScalarProduct[k1, p1] = -t1/2,
ScalarProduct[k1, p2] = (s1 + t1 - t2)/2,
ScalarProduct[k1, p3] = (s - s1 + t2)/2,
ScalarProduct[k2, p1] = (s - s2 + t1)/2,
ScalarProduct[k2, p2] = (s2 + t2 - t1 - m^2)/2,
ScalarProduct[k3, p3] = (m^2 - t2)/2, ScalarProduct[p1, p2] = s1/2,
ScalarProduct[p1, p3] = (s - s1 - s2)/2,
ScalarProduct[p2, p3] = (s2 - m^2)};
f1 = coef0 PolarizationVector[
k2, \[Mu]] SpinorUBar[k1,
0].GA[\[Mu]].QuarkPropagator[{k1 + k2, 0},
Explicit -> True].GA[\[Nu]].SpinorU[p1,
0] (-MetricTensor[\[Nu], \[Alpha]] +
FourVector[
k1 + k2 - p1, \[Nu]] FourVector[k1 + k2 - p1, \[Alpha]]/
mW^2) PropagatorDenominator[k1 + k2 - p1,
mW] SpinorVBar[p2, 0].GA[\[Alpha]].(1 - GA5). SpinorU[p3, m] // FCI
f1star = ComplexConjugate[f1]
m11 = DoPolarizationSums[f1 f1star, k2, 0]
m22 = FermionSpinSum[m11] /. DiracTrace -> TR // Contract // Simplify
Mfinal = m22
dsigbardz = coef1 Mfinal
It displays the amplitude correctly and evaluates its complex conjugation, but faols when calculating the fermion polarization sum with the error
"Error! DiracTrick has encountered a fatal problem and must abort the computation. The problem reads: Incorrect combination of dimensions and g^5 scheme!"
What is the reason for this?
This archive was generated by hypermail 2b29 : 09/04/20-12:55:05 AM Z CEST