Contributions To MadGraph generated Cross-sections

Hi Jack,

> - If I generate for something like (u, d) incoming, will Madgraph also generate for the flipped initial state (d, u)?

No.

> - If the final state includes two identical particles e.g. u u~ > e+ e- g g does Madgraph include the factor of 2 associated with this symmetry factor?

Sure

> - Does the 'output' run for MadGraph include a running alpha_s

Yes. You can control some of the parameter via the run_card.dat. The others are usually fixed by the choice of pdf.

Cheers,

Olivier

On Apr 28, 2014, at 2:11 PM, Jack Medley <email address hidden> wrote:

> New question #247835 on MadGraph5_aMC@NLO:
> https://answers.launchpad.net/mg5amcnlo/+question/247835
>
> Hello,
> I am using simple SM (with zero b mass) processes, in particular u u~ > e+ e- g g, to check another MonteCarlo is giving reasonable results and as such I need to understand a little better exactly what MadGraph does to calculate it's value for the the x-section.
> I generate in madgraph by using the usual import model, generate, output and launch routine.
> In particular I would like to know:
> - If I generate for something like (u, d) incoming, will Madgraph also generate for the flipped initial state (d, u)?
> - If the final state includes two identical particles e.g. u u~ > e+ e- g g does Madgraph include the factor of 2 associated with this symmetry factor?
> - Does the 'output' run for MadGraph include a running alpha_s
> Thanks in advance!
> Jack
>
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

Ok great. Thanks for the help!
Jack

Hello again,
Can I just double check that your above statements also hold for the standalone_cpp output?
Cheers,
Jack

Hi Jack,

The two first yes, the last one not.
We simply use the value of alpha_s provide in that case without any running.

Cheers,

Olivier