Decay width ratio

Hi,

Your syntax does request for on ONSHELL w, so yes indeed this is not going to work.
(also asking to have an onshell gluon is obviously problematic).

Actually asking to compute partial width for tau decaying with hadron is highly non trivial since you are in non perturbative regime.
You should look at the following paper:
https://arxiv.org/abs/1212.6247

Cheers,

Olivier

> On 8 Mar 2023, at 13:25, Zahra <email address hidden> wrote:
>
> New question #705756 on MadGraph5_aMC@NLO:
> https://answers.launchpad.net/mg5amcnlo/+question/705756
>
> Dear experts,
> I want to calculate the width of the tau decay in madgraph. At first I used this commad: generate ta- > vt w-, (w- > d u~ g g, g > u u~, g > d d~) to calculate the ration of decay but I got this error: zero result detected: no phase space. Please check particle masses.
>
>
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Dear Olivier,

Thank you for your response.

Sincerely yours,
Zahra