Decay width computation with new Mediator

Hi,

Since I do not know the model/benchmark, it is difficult to comment.

Since you are sensitive to the width of the Z, this likely means that the mass of n1 is higher than the mass of n1.
in that case the Z will be onshell.

and therefore your width can be seen as
> n1 > v z
times the branching ratio z > l l

So here you have plenty of choice,
- you can use auto and this will take the LO width
- you can use a NLO (or higher accuracy) for the BR
- you can use an experimental driven BR formula.
They will obviously all lead to slightly different value.
The last two are slightly inconsistent since MG5aMC works at LO for such computation.

I do not know what the default value is for your model (and if not 0 or 1 how it was computed) but if you changed the mass of n1, that value need to be changed as well.

Cheers,

Olivier

> On 10 Jan 2022, at 04:45, ouseph cj <email address hidden> wrote:
>
> New question #700152 on MadGraph5_aMC@NLO:
> https://answers.launchpad.net/mg5amcnlo/+question/700152
>
> Dear Madgraph Experts,
> I am working on the decay of Heavy Neutrino n1 > v l l,
> Currently, I have a new mediator Zprime in my theory.
> If I want to include both Z, W and Z-prime mediated processes, do I need to put the width of Z-prime to auto,
>
> I tried in both ways ( putting Z prime width to auto and using the default value), both the cases are giving different values,
> which one is the proper way to include all the channels?
>
> Best
> Ouseph
>
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