Name: Jong-Wan Lee (email_not_shown)
Date: 11/28/16-06:41:42 AM Z


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
>>
>



This archive was generated by hypermail 2b29 : 11/19/17-03:00:02 PM Z CET