Weights and PDFScales in root output

Hi Jan,

I didn’t knew that such information was include in the root file.
This was probably done for some NLO run where those information are include by default.
Those information are optional in our LO implementation, and I have no idea if they will be passed automatically to the root file.
But you can give it a try.

You will first need to include SysCalc with the command
install SysCalc
then you have to modify the run_card to set the parameter use_syst = True
Then the produced lhe file, will contain those information, the only point that I do not know if those information will be pass (and if so correctly or not) to the root file.

Cheers,

Olivier

On Nov 20, 2014, at 6:02 PM, Jan <email address hidden> wrote:

> New question #257980 on MadGraph5_aMC@NLO:
> https://answers.launchpad.net/mg5amcnlo/+question/257980
>
> Hi
>
> I was wondering if one has to set some flags to get the information about PDF scale and weights for the events?
>
> The information is included in both the hard process and showered lhe files, but Weight=1, and ScalePDF, alpha, alpha_s=0 for all events, in all the root files (pythia and delphes)
>
> I'm using MG5_aMC_v2.1.2 and use ./generate_events with pythia and delphes
>
> cheers,
> Jan
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

Hi Olivier,

thanks for the help, this indeed did the trick and the information is now in the root files. However it seems to slow down the event generation quite a bit, is it possible to turn of all variations and still run SysCalc? What I'm trying to do is reweight samples from 14 TeV to 8 TeV using PDF reweighing of the events (which requires Q for each event), is there a simpler way to do this using Reweight or SysCalc?

cheers,

Jan

Hi Jan,

This is the only way.

Cheers,

Olivier

On Nov 27, 2014, at 10:16 PM, Jan <email address hidden> wrote:

> Question #257980 on MadGraph5_aMC@NLO changed:
> https://answers.launchpad.net/mg5amcnlo/+question/257980
>
> Status: Answered => Solved
>
> Jan confirmed that the question is solved:
> Hi Olivier,
>
> thanks for the help, this indeed did the trick and the information is
> now in the root files. However it seems to slow down the event
> generation quite a bit, is it possible to turn of all variations and
> still run SysCalc? What I'm trying to do is reweight samples from 14 TeV
> to 8 TeV using PDF reweighing of the events (which requires Q for each
> event), is there a simpler way to do this using Reweight or SysCalc?
>
> cheers,
>
> Jan
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.