set condition on effective operators in autowidth calculation

Hi,

I'm not sure to fully understand your question.
Now if the question is: "is it possible to pass parameter to the auto entry in the param_card"
then the answer is no. However the "auto" option is just a shortcut to a module sometimes call MadWidth which can be call from a lot of places in the code and which allow a couple of parameter as described in the associated paper: http://arxiv.org/abs/arXiv:1402.1178

This being said what you try to do seems to be too complicated to be handle via options.
But the paper describe how the 2 body decay is handle (in a pure python way) and this should allow you to edit the UFO model in order to implement what you want.

Cheers,

Olivier

> On 16 Dec 2019, at 16:13, Tania Robens <email address hidden> wrote:
>
> New question #687179 on MadGraph5_aMC@NLO:
> https://answers.launchpad.net/mg5amcnlo/+question/687179
>
> Dear authors,
>
> I apologize if this question has already been answered here/ in a tutorial/ ... . I was wondering whether it is possible to set a condition on an effective operator (e.g. should only be used if in validity regime, e.g. set by masses or other parameters) somewhere such that is it also respected by autowidth. I found a way to do this in the actual partial decay width calculation using madgraph itself (e.g. for a > b c), but somehow this condition does not get transferred to the autowidth calculation, even if I include it in couplingsx.f or intparam_definition.inc in Source/MODEL. Is there a way to do this ? Or alternatively, to exclude certain decay channels when using autowidth ?
>
> If you have some tutorial/ documentation re this please point me to it.
>
> Thanks a lot in advance
>
> Best wishes Tania
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

Hi Olivier

sorry for the late reply. To be more concrete:

If you look at decays H -> gamma gamma using a Lagrangian with an effective vertex, then for high masses the EFT is no longer valid. This means in principle you get wrong (and usually much too large) numbers here. So the question is whether I can tell autowidth "only calculate H-> gamma gamma if mH < my favourite value", and how deep I have to dig into the code for this.

Thanks Best Tania

Hi Tania,

If your model do have a decays.py then you can change the associated value of the partial width in order to return 0 if some condition are not fullfilled.

If your model does not support that mode, then you probably want to hack the model to have a coupling value for H > a a which is multiply by a theta function.

Cheers,

Olivier

Hi Olivier

I am trying to set a condition in the .py file but somehow it does not show any effect; maybe I try the wrong way. How would you suggest to do it ?

Thanks Best Tania

I was thinking something like
for example replace this:
 (P.Xs,P.YF3u3):'OLD_EXPRESSION',
by
 (P.Xs,P.YF3u3):'( OLD_EXPRESSION if MT < 100 else 0)'

,
Cheers,

Olivier

Hi again

only in decays.py it does not seem to work... but if you modify the effective vertex in parameters.py it seems to do what I want, at least for direct decays. Thanks