NLO events before showering

Hi,

You should check the MCC@NLO method to have more details on how the matching is done and why you can not use lhe file before showering. In short we have apply within our code a substraction scheme to remove the double counting with the parton-shower. So you need to run the parton-shower to (re)fill the gap in our generation.

Now they are obviously a lot of physics within such file and therefore you can likely learn stuff from that file.
However since you do not yet have NLO accurate on the observables, I'm not sure of the gain compare to a standard LO file.

Cheers,

Olivier

> On 5 Aug 2021, at 09:35, Pim Verschuuren <email address hidden> wrote:
>
> New question #698246 on MadGraph5_aMC@NLO:
> https://answers.launchpad.net/mg5amcnlo/+question/698246
>
> Dear experts,
> When generating events at NLO QCD with showering switched off MadGraph gives a warning that these events won't be physical. Could you elaborate what this means? For example, if I would generate ttbar events at NLO QCD and have a quick first look at what the effects of changing the top mass are on the pT-distribution of the top quark, which can be obtained by analyzing the lhe-files with MadAnalysis, would I be wrong to infer anything from these pre-parton showered distributions?
> Kind regards,
> Pim
>
> --
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Hi Oliver,
Thank you for the helpful answer!
Cheers,
Pim