MadGraph5_aMC@NLO

Setting width of a user-defined particle to Auto using a script

Asked by Gowri Kurup

Hi,

I have a FeynRules model with N user-defined particles in it. I am using a script to generate events and output to a directory. For eg., for N = 5, I have the contents of the script look like the following:

    import model new_UFO
    define n = ns1 ns2 ns3 ns4 ns5
    generate p p > n e-
    output ppNe_5
    launch
    set wns1 Auto
    set wns2 Auto
    set wns3 Auto
    set wns4 Auto
    set wns5 Auto

where ns1, ns2, ns3, ns4 and ns5 are the new particles. I used wns1, wns2 etc. to refer to the widths of my particles, following the naming scheme used for the other SM particles. When I run ./bin/mg5_aMC script.sh, I get errors that say:

    set wns1 Auto
    WARNING: invalid set command wns1 Auto

I am guessing the error is that the width of my new particle is not referred to by the variable "wns1".

I don't want to go and manually change the widths in the parameter cards, as I plan to have a larger N and it will be tedious to do so by hand. I need a way to set widths of my new particles to Auto using my script. (I have another shell script that writes out scripts of this form when given the value of N). How do I figure out the variable names referring to the widths of my new particles?

Question information

Language:
English Edit question
Status:
Solved
For:
MadGraph5_aMC@NLO Edit question
Assignee:
No assignee Edit question
Solved by:
Olivier Mattelaer
Solved:
Last query:
Last reply:
Revision history for this message
Best Olivier Mattelaer (olivier-mattelaer) said : 		#1

Hi,

If you have the pdg code of those particle you can do:
set width 123456 Auto

If you want to compute the width for all particles following this method, you can do
set width all Auto
(be careful that Auto does not make sense for the HIggs if you do not have the effective operator to gluon/photon)

Now it might be possible that editting that parameter is just not allowed.
Because the model fix his value either to 0 or to a given formula

Cheers,

Olivier

> On 14 Mar 2018, at 04:32, Gowri Kurup <email address hidden> wrote:
>
> New question #665567 on MadGraph5_aMC@NLO:
> https://answers.launchpad.net/mg5amcnlo/+question/665567
>
> Hi,
>
> I have a FeynRules model with N user-defined particles in it. I am using a script to generate events and output to a directory. For eg., for N = 5, I have the contents of the script look like the following:
>
> import model new_UFO
> define n = ns1 ns2 ns3 ns4 ns5
> generate p p > n e-
> output ppNe_5
> launch
> set wns1 Auto
> set wns2 Auto
> set wns3 Auto
> set wns4 Auto
> set wns5 Auto
>
> where ns1, ns2, ns3, ns4 and ns5 are the new particles. I used wns1, wns2 etc. to refer to the widths of my particles, following the naming scheme used for the other SM particles. When I run ./bin/mg5_aMC script.sh, I get errors that say:
>
> set wns1 Auto
> WARNING: invalid set command wns1 Auto
>
> I am guessing the error is that the width of my new particle is not referred to by the variable "wns1".
>
> I don't want to go and manually change the widths in the parameter cards, as I plan to have a larger N and it will be tedious to do so by hand. I need a way to set widths of my new particles to Auto using my script. (I have another shell script that writes out scripts of this form when given the value of N). How do I figure out the variable names referring to the widths of my new particles?
>
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

Revision history for this message
Gowri Kurup (g.kurup) said : 		#2

Hi,

Thank you for the quick response!

Is there a way to predict what PDG numbers MadGraph assigns to new particles? All I know is that they usually start with 9000, but I would like to know the range of numbers to set to Auto if I know the number of new particles. Or do you think that it is better that I change the FeynRules model itself to manually assign a PDG code to each particle so that I know for sure?

Thanks,
Gowri

Revision history for this message
Olivier Mattelaer (olivier-mattelaer) said : 		#3

Hi,

MadGraph does not assign any number by itself.
All PDG code assignment are done at the FR level.
I do not know how they decide to assign those by default.

But indeed if you force those value in FR, then you have full control,

Cheers,

Olivier

> On 14 Mar 2018, at 16:27, Gowri Kurup <email address hidden> wrote:
>
> Question #665567 on MadGraph5_aMC@NLO changed:
> https://answers.launchpad.net/mg5amcnlo/+question/665567
>
> Gowri Kurup posted a new comment:
> Hi,
>
> Thank you for the quick response!
>
> Is there a way to predict what PDG numbers MadGraph assigns to new
> particles? All I know is that they usually start with 9000, but I would
> like to know the range of numbers to set to Auto if I know the number of
> new particles. Or do you think that it is better that I change the
> FeynRules model itself to manually assign a PDG code to each particle so
> that I know for sure?
>
> Thanks,
> Gowri
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

Revision history for this message
Gowri Kurup (g.kurup) said : 		#4

Thank you! I'll do that.