Unable to apply cuts in NLO

Asked by Jhuma Ghosh on 2018-10-11

Hi,
I am trying to generate p p > b b~ g [QCD] with madspin off.
But, when I am looking into the run card, there is no option to put a Pt and eta cut on b and b bar.
I tried to add set etabmin 2.5 on the shell and added it to the run card also. But, it is not taking any cut on b or b bar.

But, in LO it is possible to apply. Am I missing something?

Thanks in advance.

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Last query:
2018-10-11
Last reply:
2018-10-11

Hi,

1) your syntax "p p > b b~ g [QCD] " does not make sense for a NLO computation.
You should not use "g" in the final state with [QCD]
As stated in the following warning:

> WARNING: Process: g/u/c/d/s/u~/c~/d~/s~ g/u/c/d/s/u~/c~/d~/s~ > b b~ g WEIGHTED=3 [ all = QCD ] can have real emission processes which are not finite.
> To avoid this, please use multiparticles when generating the process and be sure to include all the following particles in the multiparticle definition:
> g, c, s, u, d, d~, u~, s~, c~

You should rather use "p p > b b~ j [QCD]"

2) Cut at NLO are more complicated than LO cut since they need to be infra-red save.
So indeed the list of cut that you can use at NLO is not the same as the one of LO.

Now you can put pt cut on the b via the command
set pt_min_cut {5:10}

Such command does not exists for the rapidity.

Cheers,

Olivier

> On 11 Oct 2018, at 13:57, Jhuma Ghosh <email address hidden> wrote:
>
> New question #675034 on MadGraph5_aMC@NLO:
> https://answers.launchpad.net/mg5amcnlo/+question/675034
>
> Hi,
> I am trying to generate p p > b b~ g [QCD] with madspin off.
> But, when I am looking into the run card, there is no option to put a Pt and eta cut on b and b bar.
> I tried to add set etabmin 2.5 on the shell and added it to the run card also. But, it is not taking any cut on b or b bar.
>
> But, in LO it is possible to apply. Am I missing something?
>
>
>
> Thanks in advance.
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

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