Name: Vladyslav Shtabovenko Date: 11/27/16-08:26:29 PM Z
Dear Jong-Wan,
the result
I \[Pi]^2 (-((A0[m^2] GA[\[Alpha]])/(2
(1 - D))) +
2 FV[p, \[Alpha]] GS[p] - ((2 - 4 D + D^2)
A0[m^2] FV[
p, \[Alpha]] GS[p])/(2 (1 - D) m^2))
is correct. What is (in general) not correct and dangerous, is to do
exp /. D->4
Please have a look at
https://github.com/FeynCalc/feyncalc/wiki/FAQ#limitto4
this should explain it better.
Cheers,
Vladyslav
Am 24.11.2016 um 06:17 schrieb Jong-Wan Lee:
> 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