LO generation with loop_qcd_qed_sm_Gmu model

Asked by Hannes on 2020-05-12

Hi,

we have large MC samples that have been generated with the 'loop_qcd_qed_sm_Gmu' model using LO mode (I've pasted an example for the full generate command below). Now we would like to be sure the events generated are physical and correspond to the SM at LO since we would like to avoid re-generating the samples. We are worried because we don't really know what to expect when using the model allowing NLO EW model at LO and compared to the generation with the LO SM model we also see additional diagrams with g+/- propagators. Do you think the samples fine or is there something that could go wrong?

Cheers,
Hannes

   set complex_mass_scheme
   import model loop_qcd_qed_sm_Gmu
   define p = g u c d s u~ c~ d~ s~ b b~
   define j = g u c d s u~ c~ d~ s~ b b~
   generate p p > mu+ vm a j j QCD=0
   add process p p > mu- vm~ a j j QCD=0

Question information

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Solved
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MadGraph5_aMC@NLO Edit question
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Solved by:
Hannes
Solved:
2020-05-12
Last query:
2020-05-12
Last reply:
2020-05-12

Hi,

I guess you will have to regenerate another sample to check the cross-section and main-shapes to be sure. You will likely see differences beacause of the choice for the EW sector and you need to know what to do about it.

> also see additional diagrams with g+/- propagators.

Those are just the goldstone boson because the computation is done in the Feynman gauge and not in the unitary gauge.

Cheers,

Olivier

> On 12 May 2020, at 11:44, Hannes <email address hidden> wrote:
>
> New question #690654 on MadGraph5_aMC@NLO:
> https://answers.launchpad.net/mg5amcnlo/+question/690654
>
> Hi,
>
> we have large MC samples that have been generated with the 'loop_qcd_qed_sm_Gmu' model using LO mode (I've pasted an example for the full generate command below). Now we would like to be sure the events generated are physical and correspond to the SM at LO since we would like to avoid re-generating the samples. We are worried because we don't really know what to expect when using the model allowing NLO EW model at LO and compared to the generation with the LO SM model we also see additional diagrams with g+/- propagators. Do you think the samples fine or is there something that could go wrong?
>
> Cheers,
> Hannes
>
>
> set complex_mass_scheme
> import model loop_qcd_qed_sm_Gmu
> define p = g u c d s u~ c~ d~ s~ b b~
> define j = g u c d s u~ c~ d~ s~ b b~
> generate p p > mu+ vm a j j QCD=0
> add process p p > mu- vm~ a j j QCD=0
>
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

Hannes (hannes3) said : #2

Hi Olivier,

thanks for the quick reply. Just so that I understand correctly: we can expect differences compared to the usual MG LO SM but the result is also physical? And there are no problems due to using the NLO model at LO?

Cheers,
Hannes