Name: Frederik Orellana (email_not_shown)
Date: 04/19/03-03:14:47 PM Z


Hello.

I tried to reproduce this behaviour. An integrand corresponding to what
you write would be:

amp = Pair[Momentum[k], Momentum[p1]]FeynAmpDenominator[
       PropagatorDenominator[k, lam], PropagatorDenominator[(k - q), lam],
       PropagatorDenominator[(k - p1), m], PropagatorDenominator[(k +
p2), M]];

With this,

OneLoop[k, amp]

evaluates without problems.

I need more details in order to help: Your integrand in FeynCalc
notation; the version of FeynCalc you're using.

Frederik

Peter Blunden wrote:
> I'm trying to do an integral that FeynCalc chokes on. The message returned
> is the usual
>
> FYI: Tensor integrals of rank higher than 3 encountered; Please use the
> option CancelQP -> True or OneLoopSimplify->True or use another program.
>
> However, it appears that CancelQP->True is the default, and OneLoopSimplify
> expresses the results in terms of Contract3, which doesn't seem to exist.
>
> The integrals are box diagrams, and a typical term would look something like
>
> (k.p1)^3 / [k^2-lam^2][(k-q)^2-lam^2][(k-p1)^2-m^2][(k+p2)^2-M^2]
>
> where p1^2=m^2 and p2^2=M^2. This term looks innocent enough, and in fact
> looks to me like it IS of rank 3. By a lot of fudging and manipulating I
> managed to get a result using ScalarProductCancel, but it is hit and miss
> for various terms in the amplitude.
>
> Is there a fix in FeynCalc, or do I have to use another program (and if so,
> which one)?



This archive was generated by hypermail 2b29 : 03/23/17-07:00:02 AM Z CET