Code review comment for lp:~maddevelopers/mg5amcnlo/2.6.3_optimizenlomodel

Hi,

To be complete I detect K=1
only if it is analytically 1 (and trivially so, i.e. if both use the same name

The case K=+/-1 is tackle ONLY for restricted model and the comparison is done numerically.
I would not like to pass to numerical comparison for ALL integer since it is too dangerous to have false positif.
Also doing K=+/-2 differs from the actual description of the restrict_model (but thate

Now it would make sense to look at the K as any integer at the analytical level.
But I'm slightly worried about the time impact (at the same time this is only the first time since it is save in the pkl). I think i will test something with string comparison:

something like:

couplings.order(key=len)
for i in range(len(couplings)):
 for j in range(i+1, len(couplings))
  c1, c2 = couplings[i], couplings[j]
  c2.expr = c2.expr.replace(str(c1), c1.name)

Then a simple regular expression should be able to detect case where

c2.expr=" 2 * GC_1"

What do you think?

Cheers,

Olivier

> On 12 Jun 2018, at 16:31, Valentin Hirschi <email address hidden> wrote:
>
> Nevermind, I worked it out again and realised what you did is basically the best you can get already. In general, if you have this interaction:
>
> particles = [p.A, p.B, p.C]
> color = ['C1','C2']
> lorentz = [L.LA, L.LB, L.LC]
> couplings = {
> (0,0): C.G1, (0,1): C.G2, (0,2): C.G3,
> (1,0): C.G4, (1,1): C.G5
> }
>
> you can generalise your procedure by defining the following two Lorentz structure being basically:
>
> L.LA + (C.G2/C.G1)*L.B + (C.G3/C.G1)*L.C
>
> and
>
> L.LA + (C.G5/C.G4)*L.B
>
> But I now realise that it's pointless/hard to do this if (C.G<i>/C.G<j>)=K , with K having model parametric dependence. You implemented this for K= +/-1, and in principle it could be extended to any integer, but that has very little value in practice indeed.
> So I agree, what you did is already basically the best you can get already.
>
> Cheers
>
> --
> https://code.launchpad.net/~maddevelopers/mg5amcnlo/2.6.3_optimizenlomodel/+merge/346864
> Your team MadDevelopers is subscribed to branch lp:~maddevelopers/mg5amcnlo/2.6.3_optimizenlomodel.