Use Pythia8 in MadGraph5 mode

Hi,

For LO processes, only PY6 is supported for on the flight shower.
Any other shower can be used externally on the generated LHEF file.
Please refer to the shower manual to see how to run those code.

For NLO processes, many shower are actually interfaced. In that case only the shower specified in the run_card can be used to shower the LHEF sample generated.
(due to the MC counter-term which is shower specific)

> Please note that the aMC operation mode fails during the generation step due to the following error:
> Command "generate p p > t t~ b QED=2 QCD=3 [QCD]" interrupted with error:
> NoDiagramException : No amplitudes generated from process Process: g/u/c/d/s/u~/c~/d~/s~ g/u/c/d/s/u~/c~/d~/s~ > t t~ b QCD=3 QED=2 [ noborn = QCD ]. Please enter a valid process

1) Not sure which kind of diagram you are expecting. I can only confirm that in 4 flavor computation:
generate p p > t t~ b
does not have any diagram even at LO.

2 ) Do you want to do the computation in 5 flavor?
if so you need to do
import model sm-no_b_mass
generate p p > t t~ b

Cheers,

Olivier

> On Aug 1, 2016, at 17:08, Marco Harrendorf <email address hidden> wrote:
>
> New question #313998 on MadGraph5_aMC@NLO:
> https://answers.launchpad.net/mg5amcnlo/+question/313998
>
> Dear MG5_aMC experts,
>
> I am trying to generate a p p > t t~ b process in the MG5 operation mode and to shower it with Pythia8.
> However, if I am typing
> launch
> it is stated that
> pythia is not installed
>
> Is Pythia8 in the MG5 operation mode not supported?
>
> How could I use Pythia8 in this case?
>
> Please note that the aMC operation mode fails during the generation step due to the following error:
> Command "generate p p > t t~ b QED=2 QCD=3 [QCD]" interrupted with error:
> NoDiagramException : No amplitudes generated from process Process: g/u/c/d/s/u~/c~/d~/s~ g/u/c/d/s/u~/c~/d~/s~ > t t~ b QCD=3 QED=2 [ noborn = QCD ]. Please enter a valid process
>
> Thank you in advance for your help
>
> --
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