fix initial/final state kinematics on different process

Hi,

No this is not possible.
I do not know what you want to do, but using the re-weighting module or the standalone package will allow you to get the matrix-element for the second matrix-element for that given phase-space point.

Cheers,

Olivier

PS: For the re-weighting package, you might need to do a plugin since you do not preserve the identity of the particles.
Another trick is to change the UFO model to change the pdg particle of the up/down and then use the standard re-weighting module

Hello,

Thank you for your answer.

What I am trying to do is getting weights of all possible initial parton contributions event by event.

How I interpreted your answer of using re-weight is following:

1. I used "model SMEFTsim_U35_MwScheme_UFO" as a reweight reference point ( using MG5_aMC_v3_1_1 )
2. generate u u~ > e+ e- NP<=1
3. Then write reweight card as

      change model SMEFTsim_U35_MwScheme_UFO
      change process d d~ > e+ e- NP<=1
      change helicity False

      launch --rwgt_name=case1
      set SMEFT 1 0.

and so on

Once I run it, it causes following error and shuts down. I surmise this is what you mentioned about not preserving the identity and must be connected to your comment on "plugin." Do you mind elaborate more on "do a plugin"?

CRITICAL: The following initial/final state ((-2, 2), (-11, 11)) can not be found in the new model/process. If you want to set the weights of such events to zero use "change allow_missing_finalstate False"
Command "generate_events run_01" interrupted with error:

Even though I added "change allow_missing_finalstate False" in reweight card, it did not work.

Thank you,

Tae Kim

A plugin is explained here:

https://cp3.irmp.ucl.ac.be/projects/madgraph/wiki/Plugin

but at the end if you do not plan to share it, it is the same that changing
madgraph/interface/reweight_interface.py
to allow to link event with "u u~" initial state to a matrix-element which does not have "u u~" in the initial state.

But maybe here the easiest is that you use the standalone mode (but then the handling of reading/re-writting the lhef file would be on your side)

Cheers,

Olivier

> On 11 Apr 2022, at 13:31, Tae Kim <email address hidden> wrote:
>
> Question #701220 on MadGraph5_aMC@NLO changed:
> https://answers.launchpad.net/mg5amcnlo/+question/701220
>
> Status: Answered => Open
>
> Tae Kim is still having a problem:
> Hello,
>
> Thank you for your answer.
>
> What I am trying to do is getting weights of all possible initial parton
> contributions event by event.
>
> How I interpreted your answer of using re-weight is following:
>
> 1. I used "model SMEFTsim_U35_MwScheme_UFO" as a reweight reference point ( using MG5_aMC_v3_1_1 )
> 2. generate u u~ > e+ e- NP<=1
> 3. Then write reweight card as
>
> change model SMEFTsim_U35_MwScheme_UFO
> change process d d~ > e+ e- NP<=1
> change helicity False
>
> launch --rwgt_name=case1
> set SMEFT 1 0.
>
> and so on
>
> Once I run it, it causes following error and shuts down. I surmise this
> is what you mentioned about not preserving the identity and must be
> connected to your comment on "plugin." Do you mind elaborate more on "do
> a plugin"?
>
> CRITICAL: The following initial/final state ((-2, 2), (-11, 11)) can not be found in the new model/process. If you want to set the weights of such events to zero use "change allow_missing_finalstate False"
> Command "generate_events run_01" interrupted with error:
>
> Even though I added "change allow_missing_finalstate False" in reweight
> card, it did not work.
>
> Thank you,
>
> Tae Kim
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.