S-channel Propagater Exception ($ operator)

Hi NiKlas,

The $ syntax is the on shell subtraction term.
More details on page 119 of the following paper: arXiv:1405.0301
and/or in this tutorial: https://cp3.irmp.ucl.ac.be/projects/madgraph/attachment/wiki/MGTalks/13_06_10_tutomg_tasi.pdf

Since this is a on shell subtraction, this is normal to have the diagram, just that the propagator associate to the particle is modified and is zero if the invariant mass is close to the pole mass

Cheers,

Olivier

On Jun 10, 2014, at 2:37 AM, Niklas Garner <email address hidden> wrote:

> New question #250010 on MadGraph5_aMC@NLO:
> https://answers.launchpad.net/mg5amcnlo/+question/250010
>
> Hey all,
>
> I'm working on generating a WW scattering sample and I can't seem to get it exactly right. I'm using version 2.1.1 and the process I'm using is:
>
> p p > a p p /z h $ w+ w- QCD=0 QED=3, ( a > w+ w- QED = 1 )
>
> What I hope to have is where the two protons scatter by emitting a WW pair which then scatter through a (s-channel) photon which then produces a WW pair once again.
>
> While most of subprocess diagrams are what I expect, one of them has the protons scatter through a (s-channel) W which then emits the photon. My understanding is that the $w+ w- would avoid this process, but this seems not to be the case.
>
> Is there something I may have overlooked?
>
>
> Thanks,
>
> Niklas
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

Thanks for the quick reply Olivier,

What would be the appropriate process I would need to run in order to get the diagrams I want to make?

Something like

p p > w+ w- p p / h z ( w+ w- > a > w+ w-)

But this is obviously incorrect syntax. Am I stuck with that extra process?

Niklas

Forget about that last question, I was able to figure it out with the help of the tutorial you provided.

The $$ operator was what I was looking for!