Name: Rakhi Date: 04/14/15-02:20:34 PM Z
Hi, I’m computing a spin sum and propagator contraction with FeynCalc 8.2.0 and the results of the contraction don’t agree with what I expect (also disagrees with computation by hand).
Code to get spin sum
====================================
ClearScalarProducts
ScalarProduct[q, q] = M^2; ScalarProduct[k1, k1] =
m1^2;
ScalarProduct[k2, k2] = m2^2; ScalarProduct[k3, k3] =
m3^2;
ScalarProduct[k2, k3] = 1/2 (M^2 + m1^2 - m2^2 - m3^2 - 2
ScalarProduct[q, k1]);
ScalarProduct[k1, k3] = 1/2 (M^2 - m1^2 + m2^2 - m3^2 - 2
ScalarProduct[q, k2]);
ScalarProduct[k1, k2] = 1/2 (M^2 - m1^2 - m2^2 + m3^2 - 2
ScalarProduct[q, k3]);
ScalarProduct[k3, q] = M^2 - ScalarProduct[q, k2] -
ScalarProduct[k1, q];
m2 := 0;
s1 = Spinor[q, M].GA[\[Mu]].(-Ni2 GA[7]
Then I contract with a massive W propagator:
=============================
prop[\[Mu]_, \[Nu]_, p_, m_] :=
(MT[\[Mu], \[Nu]] - (FV[p,
\[Mu]] FV[p, \[Nu]])/m^2);
Ampsq = Contract[prop[\[Rho], \[Sigma], q -
k1, mw].Mint.prop[\[Mu], \[Nu], q - k1,
mw]];
=============================
Am I not using the commands correctly, or is there some sort of bug?
Many thanks in advance for your help,
Rakhi