Name: Vladyslav Shtabovenko (email_not_shown)
Date: 02/03/17-05:20:03 PM Z


Hi,

Am 01.02.2017 um 15:09 schrieb Pablo Sanchez Puertas:
> Hello again!
>
> Thanks for the long answer and explanations. As I said, don't worry
> about the implementation in FeynCalc: I understand that such a task
> would represent quite some work and I already managed myself to get
> the numerics for the particular cases I need.
> Moreover, I could check that, as you said, TID[] works propperly
> whenever non-vanishing Gram determinants appear; in that case the
> option UsePaVeBasis->True does the work perfectly anyway. So I guess
> that is a nice and general advice.
>
> On the other hand, concerning the current implementation, as I said,
> there are still some terms which are missing and not included in the
> references you showed me, but which appear in
> http://dx.doi.org/10.1016/S0550-3213(03)00184-6
> (still, as far as I know, not using DR for IR divergences). You could,
> for instance, compare numerically with the result obtained from TID[]
> and evaluating it numerically with LoopTools. In that sense, I thought
> that would be worthy in the new version that OneLoop[] does not either
> produce any output for the tensor integrals or produce some warning.

This should be now fixed, i.e. tensor 5-point functions are not reduced
to boxes anymore. The formula is applied only to pure scalars integrals.
Also OneLoop by itself will be considerably reworked for the next release...

>
> At the moment, I could not come up with an easy and systematic mehtod
> to do the reduction of tensor integrals and I have not used DR for IR
> divergences, so I cannot help with the implementation. Anyhow, if in
> the future I can come up with some method, I will let you know.

>
> Thanks a lot and congrats for the support,
> Pablo
>

Cheers,
Vladyslav



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