How are pythia_lhe.gz files generated by Madgraph ?

Asked by Komal on 2019-08-22

Dear MadGraph team,

I am having some troubles while using Madgraph generated pythia6 files for madanalysis.
I am not really able to figure out how the pythia_lhe.gz files are created by MadGraph. Also whats the difference between the pythia_hep.gz and pythia_lhe.gz files?

Will wait for our reply.

Best,
Komal

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Last query:
2019-08-22
Last reply:
2019-08-22

Hi,

Let me stress that pythia6 is not supported anymore (since a very long time actually)
This include both the code itself (since at least 2011) and the interface to MG5aMC (since at least 2015).

Consequently, I will only answer by what I remember of it and therefore I can be wrong/imprecise.

> I am not really able to figure out how the pythia_lhe.gz files are created by MadGraph.

The file is created by reading the hepmc file and applying a cone jet algorithm in order.
The resulting particle are then written in the lhe convention.
I have heard some rumor that such conversion was also including some smearing to behave more like a real detector.
What is clear is that you loose a lot of information (compare to the hepmc file) and that such file can only be use for specific case (in top of that, the jet algorithm use is not infra-red save and therefore one needs to be carefull about that as well.

> Also whats the difference between the pythia_hep.gz and pythia_lhe.gz files?

I guess the above description explained the physics difference, the rest is matter of convention.

Cheers,

Olivier

> On 22 Aug 2019, at 17:08, Komal <email address hidden> wrote:
>
> New question #683175 on MadGraph5_aMC@NLO:
> https://answers.launchpad.net/mg5amcnlo/+question/683175
>
> Dear MadGraph team,
>
> I am having some troubles while using Madgraph generated pythia6 files for madanalysis.
> I am not really able to figure out how the pythia_lhe.gz files are created by MadGraph. Also whats the difference between the pythia_hep.gz and pythia_lhe.gz files?
>
> Will wait for our reply.
>
> Best,
> Komal
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

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