WARNING: For consistency, the width of particle 6000002 (nu) is changed to 0.0.

Asked by Hongxin Wang on 2020-12-27

hi,

i am confirming the correctness of a new physical model , and my way is to creat a param_card.dat by fortran and use it to replace the param_card.dat in MG5. In fortran, i changed the mass of new particals and set their decay width to "Auto".

when i running MG5+Pythia8, in terminal shows as follows:

WARNING: For consistency, the width of particle 6000002 (nu) is changed to 0.0.
WARNING: For consistency, the width of particle 6000001 (nd) is changed to 0.0.

i changed another set of data, the result can not change.

i hope you can give me some advice.

thanks!

Question information

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Last query:
2020-12-27
Last reply:
2020-12-27

This means your UFO model has hardcoded the value of the width to zero consequently MG5aMC
use simpler propagator and has adapted his phase-space integrator accordingly.

The warning that you see are a self consistency check to ensure that your card is compatible with the model. MG5aMC will ignore the value of the width even if you bypass such self consistency check since the code does not have any place holder for the width.

The only solution is to edit the UFO model and allow such width to be a variable and not a constant parameter.

Cheers,

Olivier

> On 27 Dec 2020, at 03:20, Hongxin Wang <email address hidden> wrote:
>
> New question #694685 on MadGraph5_aMC@NLO:
> https://answers.launchpad.net/mg5amcnlo/+question/694685
>
> hi,
>
> i am confirming the correctness of a new physical model , and my way is to creat a param_card.dat by fortran and use it to replace the param_card.dat in MG5. In fortran, i changed the mass of new particals and set their decay width to "Auto".
>
> when i running MG5+Pythia8, in terminal shows as follows:
>
> WARNING: For consistency, the width of particle 6000002 (nu) is changed to 0.0.
> WARNING: For consistency, the width of particle 6000001 (nd) is changed to 0.0.
>
> i changed another set of data, the result can not change.
>
> i hope you can give me some advice.
>
> thanks!
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

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