Name: Jong-Wan Lee (email_not_shown)
Date: 11/24/16-06:17:58 AM Z


Dear Frederik,

I used to use Feyncalc 8.2.0 on Mathematica 9, and recently I started to
use Feyncalc 9.2.0 on Mathematica 11. However, I encountered a problem in
doing the one loop integral,

SP[p,p]=m^2;(*kinematics*)
SetOptions[B0, BReduce->True, B0Unique->True, B0Real->True];
OneLoop[k, FVD[k, \[Alpha]].GSD[k] FAD[{k, m}, p - k]];

In the old version, I have

I \[Pi]^2 (m^2 DiracGamma[LorentzIndex[\[Alpha]]]+8 DiracGamma[Momentum[p]]
Pair[LorentzIndex[\[Alpha]],
   Momentum[p]] )/9 + (
 I \[Pi]^2 A0[m^2] (m^2 DiracGamma[LorentzIndex[\[Alpha]]] +
    2 DiracGamma[Momentum[p]] Pair[LorentzIndex[\[Alpha]],
      Momentum[p]]))/(6 m^2)

but, in the new version, I have

2 I \[Pi]^2 DiracGamma[Momentum[p]] Pair[LorentzIndex[\[Alpha]],
   Momentum[p]] + (
 I \[Pi]^2 A0[m^2] (m^2 DiracGamma[LorentzIndex[\[Alpha]]] +
    2 DiracGamma[Momentum[p]] Pair[LorentzIndex[\[Alpha]],
      Momentum[p]]))/(6 m^2)

Comparing the two results, I find that the second terms which include the
UV divergence terms are same, but the first finite terms are different. In
fact the result from the old version is the correct one. Can you help me to
resolve this problem?

Best regards,
Jong-Wan



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