Name: V. Shtabovenko (email_not_shown)
Date: 10/21/17-12:31:01 PM Z


Just in case someone stumbles over this old thread:

Yes, in FeynCalc 9.3 we do have a function to analyze the UV (not IR!!!)
divergences of arbitrary Passarino-Veltman coefficient functions, c.f.

https://feyncalc.org/forum/1287.html

I recommend to use it with the global option

$KeepLogDivergentScalelessIntegrals set to True

Then:

A0[m^2] // PaVeUVPart

-> -((2 m^2)/(-4 + D))

or

B0[SPD[p, p], 0, m^2] // PaVeUVPart

-> -(2/(-4 + D))

Alternatively (or as a cross-check) one could use PaXEvaluateUV /
PaXEvaluateUVIRSplit from the FeynHelpers extension. PaXEvaluateUV uses
Package-X, while PaVeUVPart uses a different algorithm from Georg Sulyok
(https://inspirehep.net/record/727190)

Cheers,
Vladyslav

> Rolf,
>
> Thanks for the variation of the notebook. I have two questions:
>
> 1. Does FeynCalc have functions that allow for the analysis of the two point
> integrals A0, B0 etc. in the limit D -> 4+e so that the divergent parts of
> the self energies can be extracted and analysed?
>
> 2. Is it possible to use TARCER to perform the same calculation as done in
> my notebook but for two loop diagrams? My attempt to do this is in the
> attached file. I have tried applying ToTFI to the results of CreateFCAmp but
> very few of the terms correctly reduce to TFI form. I deduce from looking at
> the results from ToTFI that the problem lies at least partly in the fact
> that ToTFI does not deal with terms with numerators containing odd powers of
> the internal loop momenta q1 and q2. Presumably these terms are zero by
> symmetric integration. Are there TARCER functions that allow for these terms
> to be handled (some sort of analogue of OneLoopSimplify)?
>
> Many thanks
> Jon Palmer



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