I want to generate events in which two gluons emitted from protons interact through a box diagram, ultimately transforming into two photons

Hi,

I guess the syntax that you are looking for is

generate g g > a a QCD<=2 [noborn=QCD]
output
launch

Cheers,

Olivier

> On 9 Jan 2024, at 07:30, Rahul Shaw <email address hidden> wrote:
>
> New question #708932 on MadGraph5_aMC@NLO:
> https://answers.launchpad.net/mg5amcnlo/+question/708932
>
> I am new to using madgraph, i can't generate 2 photon events from gluons interacting through a box diagram.
>
> I tried the coomand
>
> generate p p > a a [virt = QCD]
> output loop
> launch
>
> issues:
>
> 1) I am getting three sub process out of which only one is gluon initiated and rest two are quark initiated . How to get only gluon initiated box diagram ?
>
> 2) after the launch i want to generate 10000 events but i am not getting any run card option.
>
> MG5_aMC>launch
> Do you want to edit a card (press enter to bypass editing)?
> /------------------------------------------------------------\
> | 1. param : param_card.dat |
> | 2. MadLoopParams : MadLoopParams.dat |
> \------------------------------------------------------------/
>
> how to generate 10000 events of photon production from gluon initiated box diagram ?
>
> I am really stuck at this point and I would appreciate any guidance one can offer.
>
>
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