Error for 2>1 processes with massive fermion in the final state

[Olivier Mattelaer]

Hi and HNY!

I do not know if this problem is a bug or if it is me which is doing something wrong. Therefore, I put it in the "questions" and not in the "bugs" section.

I have generated a UFO model from a FeynRules implementation of the model given in arXiv;1003.3173. The Lagrangian is taken from there, up to some parameter redefinitions. In order to validate my implementation, I have generated the two following processes

1) define PP = u g
     generate PP PP > t

2) define PPbar = ubar g
     generate PPbar PPbar > t~

and started to calculate the total cross section (with the same parameters as in page 7 (muR = muF = mt, CTEQ6L1, etc...). I have produced numbers for the three colliders, namely LHC7, LHC14 and Tevatron. I found a good agreement for the single antitop numbers, but not for the single top cross section. More importantly, in the case of the Tevatron, both the single top and single antitop cross section should be equal (p pbar initial state), which is not what I am finding with MG5.

To cross check the FR model, I have also verified tZ production (which involves the same new physics vertices) and here everything is fine (even for the Tevatron). And there it works.

I am therefore puzzled. Would it be possible that something fails for 2>1 processes?

Cheers,

Benjamin

PS: I can send the UFO model by e-mail (I don't know how to attach a file to a question).