# How to generate QED = 6 process

Asked by Songshaptak De on 2018-07-18

Hi all,

I am trying to generate the following process : p p > w+ w- j j, w+ > j j, w- > e- ve~ QCD=0 QCD=6
But when I am giving it to the madgraph, it is showing a message "Interpreting 'QED=6' as 'QED<=6'" and then generating processes with QCD =2 and QED = 4.
So, my question is how to generate the process p p > w+ w- j j, w+ > j j, w- > e- ve~ with QCD = 0 coupling and QED =6 coupling ?

~ Saptak

## Question information

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Solved by:
Olivier Mattelaer
Solved:
2018-07-18
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2018-07-18
2018-07-18
 Olivier Mattelaer (olivier-mattelaer) said on 2018-07-18: #1

Hi,

Your first error is that each part of the process have their own coupling order.
so what you want to do is actually

> generate p p > w+ w- j j QCD=0 , w+ > j j , w- > e- ve~

Cheers,

Olivier

PS: It is also possible to define a global coupling but then it should be written AFTER the @X syntax
i.e. the following is also working
> generate p p > w+ w- j j QCD=0 , w+ > j j , w- > e- ve~ @0 QCD=0

Cheers,

Olivier

> On 18 Jul 2018, at 11:12, Songshaptak De <email address hidden> wrote:
>
> New question #670946 on MadGraph5_aMC@NLO:
>
> Hi all,
>
> I am trying to generate the following process : p p > w+ w- j j, w+ > j j, w- > e- ve~ QCD=0 QCD=6
> But when I am giving it to the madgraph, it is showing a message "Interpreting 'QED=6' as 'QED<=6'" and then generating processes with QCD =2 and QED = 4.
> So, my question is how to generate the process p p > w+ w- j j, w+ > j j, w- > e- ve~ with QCD = 0 coupling and QED =6 coupling ?
>