# Now why LoopTools do not make calculation

In deed I still in calculating the self energy diagram I started in this post

Here is the code I use after the last answer

<< FeynArts;
<< FormCalc;

tops = CreateTopologies[1, 1 -> 1, ExcludeTopologies -> Internal];

ins := InsertFields[tops, F[1, {1}] -> F[1, {1}],
InsertionLevel -> {Particles}]

ClearProcess[];

amp = CalcFeynAmp[CreateFeynAmp[ins, Truncated -> True], OnShell -> False, FermionChains -> VA]


Squaring the amplitude and set arbitrary values for all unknown parameters

matrix = SquaredME[amp] //. HelicityME[amp] //. Hel[_] -> 0

VALUES = {Den[p2_, m2_] :> 1/(p2 - m2), Alfa -> 1/128,
Alfa2 -> 1/128^2, SW2 -> 0.23, CW2 -> 0.99 , ME2 -> 0.001,
Finite -> 1, MW2 -> 6400, MZ2 -> 8100};


MyResul = mat //. Subexpr[] //. Join[VALUES] // Simplify

which yeilds:

4.65923*10^-7 (1.49 + 1. B0i[bb1, Pair[k[1], k[1]], 0, 8100] +
1.98 B0i[bb1, Pair[k[1], k[1]], 0.001, 6400]) (1.49 +
1. Superscript[B0i[bb1, Pair[k[1], k[1]], 0, 8100],"*"] +
1.98 Superscript[B0i[bb1, Pair[k[1], k[1]], 0.001, 6400],"*"]) (1. Mat[F3, F3] + 1. Mat[F3, F4] + 1. Mat[F4, F3] + 1. Mat[F4, F4])


Now to get a numerical result for my calculation I should to use LoopTools because it should deal with quantities like Mat[F3, F4] and B0i[bb1, Pair[k[1], k[1]] .. But LoopTools returns the same MyResul without doing any thing

   In[]:= Install["LoopTools"]

Linux/bin/LoopTools", 666, 5]

In[]:=MyResul

Out[]= 4.65923*10^-7 (1.49 + 1. B0i[bb1, Pair[k[1], k[1]], 0, 8100] +
1.98 B0i[bb1, Pair[k[1], k[1]], 0.001, 6400]) (1.49 +
1. Superscript[B0i[bb1, Pair[k[1], k[1]], 0, 8100],"*"] +
1.98 Superscript[
B0i[bb1, Pair[k[1], k[1]], 0.001, 6400],"*"]) (1. Mat[F3, F3] +
1. Mat[F3, F4] + 1. Mat[F4, F3] + 1. Mat[F4, F4])


Note that all packages are installed in a right way as i added them to the Math link .. but probably there is some thing wrong in the code ..

• You may find it helpful to directly contact the author of LoopTools, T. Hahn, since he would be most familiar with the inner workings of that package. Oct 6 '16 at 13:03
• Some times it's better to ask some one who uses these packages than asking the authors themselves !
– S.S.
Oct 6 '16 at 15:58
• Maybe, but also asking the developer directly gives them a better idea of how their package is being used, so as to improve the package documentation. Oct 6 '16 at 17:59
• @QuantumDot . So I'd like to know is asking about these Math. packages allowed here, because i try to contact vsht who give me a useful answer about a previous post but I have no a reply .. I think questions here "about these tools" are sometimes "at least mine" has nothing to do with techniques need authors improvement for a package, but it can be much easier than that ..
– S.S.
Oct 9 '16 at 21:04
• To be completely clear, I was only giving you a suggestion that may end up being more fruitful. It is not at all forbidden to ask questions about packages here, and indeed you can get some helpful hints. But it seems that in this particular case, no one is able to help you (no answers at the time of this comment), so best to contact the package author directly. :) Oct 9 '16 at 21:06