**Next message:**Natthawin Cho: "Get"**Previous message:**Vladyslav Shtabovenko: "Re: qcd beta function?,etc"**In reply to:**Vladyslav Shtabovenko: "Re: OneLoop calculation from FeynCalc on Mathematica 11"**Messages sorted by:**[ date ] [ thread ] [ subject ] [ author ]**Mail actions:**[ respond to this message ] [ mail a new topic ]

Thank you for your kindly answer!

Best,

Jong-Wan

On Mon, Nov 28, 2016 at 4:26 AM, Vladyslav Shtabovenko <

dev@shtabovenko.df-kunde.de> wrote:

*> 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
*

*>>
*

*>
*

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