Name: Mario Schenberg Date: 11/12/14-02:47:03 AM Z


Hi,

I’m doing a 1-loop computation in the Standard Model and I find different results depending on the order in which I use the functions DiracSimplify and OneLoop. Is it normal? I only get the correct result if I apply DiracSimplify before OneLoop.

Thanks in advance.
MS.

*Method 1 (gives the correct):

num3 = Spinor[q - p, mb . dm[a] . PL . (ds[k] + mi) . dm[a] . PL . (ds[q] - ds[p] + 0) . dm[f] . (2 sw^2 - PL) . Spinor[-p, 0] ;
Simplify[DiracSimplify[num3]] ;
amp3 = %*FeynAmpDenominator[PropagatorDenominator[k, mi],
   PropagatorDenominator[q - p - k, mW]];
I3 = Simplify[OneLoop[k, amp3]];

*Method 2 (gives the wrong result):

amp3w = num3*
  FeynAmpDenominator[PropagatorDenominator[k, mi],
   PropagatorDenominator[q - p - k, mW]];
I3w = Simplify[OneLoop[k, amp3w]];