p p > t t [noborn=QED]

Hi,

The reason is that the default SM model has diagonal CKM matrix and this process doesn’t exists in that case.
you need to start by the following line
import model loop_qcd_qed_sm
generate p p > t t [noborn=QED]

Cheers,

Olivier

On 08 Jun 2015, at 20:21, Joshua Isaacson <email address hidden> wrote:

> Question #267909 on MadGraph5_aMC@NLO changed:
> https://answers.launchpad.net/mg5amcnlo/+question/267909
>
> Description changed to:
> I was attempting to generate the p p > t t cross section using the 2.3.0
> beta version of MadGraph, which I was told at MC4BSM was able to
> generate this result. I made sure to import the sm model including the
> CKM matrix. Mainly, I was interested in what the diagrams looked like.
> When I run the code I get the following output:
>
> MG5_aMC>define p = p b b~
> Defined multiparticle p = g u c d s b u~ c~ d~ s~ b~
> MG5_aMC>generate p p > t t [noborn=QED]
> INFO: Checking for minimal orders which gives processes.
> INFO: Please specify coupling orders to bypass this step.
> INFO: Trying coupling order WEIGHTED=2
> INFO: Trying coupling order WEIGHTED=3
> INFO: Trying coupling order WEIGHTED=4
> INFO: Trying coupling order WEIGHTED=5
> INFO: Trying coupling order WEIGHTED=6
> INFO: Trying coupling order WEIGHTED=7
> INFO: Trying coupling order WEIGHTED=8
> INFO: Trying coupling order WEIGHTED=9
> INFO: Trying coupling order WEIGHTED=10
> INFO: Trying coupling order WEIGHTED=11
> Command "generate p p > t t [noborn=QED]" interrupted with error:
> NoDiagramException : No amplitudes generated from process Process: g/u/c/d/s/b/u~/c~/d~/s~/b~ g/u/c/d/s/b/u~/c~/d~/s~/b~ > t t WEIGHTED=60 [ noborn = QED ]. Please enter a valid process
>
> If you could please let me know what I am doing wrong that would be
> greatly appreciated.
>
> The talk I am referring to can be found here:
> https://indico.fnal.gov/getFile.py/access?contribId=5&sessionId=1&resId=0&materialId=slides&confId=9361.
> Specifically, the second to last slide says that the syntax to generate
> this process is as I have used above, but it does not work for me.
>
> Thank you for your time.
>
> Josh
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

Hi,

Shouldn't it be:

import model loop_qcd_qed_sm-ckm

instead of:

import model loop_qcd_qed_sm?

Since the default restrictions for loop_qcd_qed_sm still sets the CKM matrix to diagonal?

Regards,
Josh

Thanks Olivier Mattelaer, that solved my question.