Problem with single-stop (mssm) production

Asked by Alexis Kalogeropoulos on 2017-09-14

Hello

I am trying to get some events from a p p > t1 x- process with up to 2 partons. Generating the diagrams works fine, but while generating events I get the error

Survey return zero cross section.
   Typical reasons are the following:
   1) A massive s-channel particle has a width set to zero.
   2) The pdf are zero for at least one of the initial state particles
      or you are using maxjetflavor=4 for initial state b:s.

but there is not obvious wrong to me to my cards (in principle, the same param_card and run_card work fine for stop-pair production).

You can find the cards here

http://desy.de/~alkaloge/single-stop

Thanks

Alexis

Question information

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MadGraph5_aMC@NLO Edit question
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Last query:
2017-09-14
Last reply:
2017-09-15

Hi Alexis,

How are you? I did not see you for a while!

Here is some comment:

1) When looking at your syntax, I realise that you did not veto the on shell resonance related to the 1j/2j final state.
This means that such generation fully overlaps the stop-pair production. This also complexifies the matching/merging algo and the required validation.
Did you do that on purpose?

2) you are using the mssm_v4 model. Is this on purpose? Or is it just because you did not realise that we remove the mssm model?
   We have now a MSSM_SLHA2 model which replace the previously UFO mssm model. The mssm_v4 model is more limited compare to the UFO counterpart.

   To have the equivalent of the old UFO model you can do the following:
   import model MSSM_SLHA2
   generate XXX
   add process XXXXX
   output
   launch
   PATH_TO_YOUR_SLHA1_CARD
   update to_slha2

3) When I run ./bin/generate_events in the madevent tarsal available in your link. I have:
  === Results Summary for run: run_01 tag: tag_1 ===

     Cross-section : 5.543 +- 0.01578 pb
     Nb of events : 10000
Is that tarball up-to-date? I wanted to check the value of your coupling, but looks like that you do not have attach the related log.
Since I can not reproduce your result, I'm not sure what I can do.

4) When doing that run, I have two warning but that should be fine:
WARNING: Missing mass in the lhef file (23) . Please fix this (use the "update missing" command if needed)
WARNING: Missing mass in the lhef file (6) . Please fix this (use the "update missing" command if needed)

Cheers,

Olivier

> On 14 Sep 2017, at 11:48, Alexis Kalogeropoulos <email address hidden> wrote:
>
> New question #658000 on MadGraph5_aMC@NLO:
> https://answers.launchpad.net/mg5amcnlo/+question/658000
>
> Hello
>
> I am trying to get some events from a p p > t1 x- process with up to 2 partons. Generating the diagrams works fine, but while generating events I get the error
>
> Survey return zero cross section.
> Typical reasons are the following:
> 1) A massive s-channel particle has a width set to zero.
> 2) The pdf are zero for at least one of the initial state particles
> or you are using maxjetflavor=4 for initial state b:s.
>
> but there is not obvious wrong to me to my cards (in principle, the same param_card and run_card work fine for stop-pair production).
>
> You can find the cards here
>
> http://desy.de/~alkaloge/single-stop
>
> Thanks
>
> Alexis
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

Hi Olivier

Nice to hear from you !

>Here is some comment:
>1) When looking at your syntax, I realise that you did not veto the on shell resonance related to the 1j/2j final state.
>This means that such generation fully overlaps the stop-pair production. This also complexifies the matching/merging algo and the >required validation.
>Did you do that on purpose?
ah, you re right! then that means that I should not include s s~ in my jet definition or something else ? Can you suggest a correct syntax ?

>2) you are using the mssm_v4 model. Is this on purpose? Or is it just because you did not realise that we remove the mssm model?
> We have now a MSSM_SLHA2 model which replace the previously UFO mssm model. The mssm_v4 model is more limited compare >to the UFO counterpart.

you re right - I was not aware of the MSSM_SLHA2 model - will try to update MG and rebuild my madevent

 >To have the equivalent of the old UFO model you can do the following:
 >import model MSSM_SLHA2
 >generate XXX
 >add process XXXXX
 >output
 >launch
 >PATH_TO_YOUR_SLHA1_CARD
 >update to_slha2

>3) When I run ./bin/generate_events in the madevent tarsal available in your link. I have:
>=== Results Summary for run: run_01 tag: tag_1 ===
> Cross-section : 5.543 +- 0.01578 pb
> Nb of events : 10000
>Is that tarball up-to-date? I wanted to check the value of your coupling, but looks like that you do not have attach the related log.
>Since I can not reproduce your result, I'm not sure what I can do.
>See More
 >To have the equivalent of the old UFO model you can do the following:
 >import model MSSM_SLHA2
 >generate XXX
 >add process XXXXX
 >output
 >launch
 >PATH_TO_YOUR_SLHA1_CARD
 >update to_slha2

>3) When I run ./bin/generate_events in the madevent tarsal available in your link. I have:
>=== Results Summary for run: run_01 tag: tag_1 ===
> Cross-section : 5.543 +- 0.01578 pb
> Nb of events : 10000
>Is that tarball up-to-date? I wanted to check the value of your coupling, but looks like that you do not have attach the related log.
>Since I can not reproduce your result, I'm not sure what I can do.

I copied the madevent tarball from the directory itself, but looks like you are getting something sensible, while I don't... But did you replace the param_card and run_card first with the ones I provided in the dir itself ?

Regards

Alexis

Hi,

> ah, you re right! then that means that I should not include s s~ in my jet definition or something else ? Can you suggest a correct syntax ?

My advise is the forbid some particle to be on shell.
You can use the $ syntax for that
For example in case of squark production, you have to do
Generate p p > sq sq~
Add process p p > sq sq~ j $ go

You can find more information on the $ syntax in the following tutorial:
https://cp3.irmp.ucl.ac.be/projects/madgraph/attachment/wiki/Shanghai2015/Tutorial_shangai_basic_mg5.pdf

>
> I copied the madevent tarball from the directory itself, but looks like
> you are getting something sensible, while I don't... But did you replace
> the param_card and run_card first with the ones I provided in the dir
> itself ?

No I keep the default one. But then this shows that you have a benchmark problem
(One reason might be that mssm_v4 does not cover your benchmark)

Cheers,

Olivier

> On 15 Sep 2017, at 09:44, Alexis Kalogeropoulos <email address hidden> wrote:
>
> Question #658000 on MadGraph5_aMC@NLO changed:
> https://answers.launchpad.net/mg5amcnlo/+question/658000
>
> Alexis Kalogeropoulos posted a new comment:
> Hi Olivier
>
> Nice to hear from you !
>
>> Here is some comment:
>> 1) When looking at your syntax, I realise that you did not veto the on shell resonance related to the 1j/2j final state.
>> This means that such generation fully overlaps the stop-pair production. This also complexifies the matching/merging algo and the >required validation.
>> Did you do that on purpose?
> ah, you re right! then that means that I should not include s s~ in my jet definition or something else ? Can you suggest a correct syntax ?
>
>> 2) you are using the mssm_v4 model. Is this on purpose? Or is it just because you did not realise that we remove the mssm model?
>> We have now a MSSM_SLHA2 model which replace the previously UFO mssm model. The mssm_v4 model is more limited compare >to the UFO counterpart.
>
>
> you re right - I was not aware of the MSSM_SLHA2 model - will try to update MG and rebuild my madevent
>
>> To have the equivalent of the old UFO model you can do the following:
>> import model MSSM_SLHA2
>> generate XXX
>> add process XXXXX
>> output
>> launch
>> PATH_TO_YOUR_SLHA1_CARD
>> update to_slha2
>
>> 3) When I run ./bin/generate_events in the madevent tarsal available in your link. I have:
>> === Results Summary for run: run_01 tag: tag_1 ===
>> Cross-section : 5.543 +- 0.01578 pb
>> Nb of events : 10000
>> Is that tarball up-to-date? I wanted to check the value of your coupling, but looks like that you do not have attach the related log.
>> Since I can not reproduce your result, I'm not sure what I can do.
>> See More
>> To have the equivalent of the old UFO model you can do the following:
>> import model MSSM_SLHA2
>> generate XXX
>> add process XXXXX
>> output
>> launch
>> PATH_TO_YOUR_SLHA1_CARD
>> update to_slha2
>
>> 3) When I run ./bin/generate_events in the madevent tarsal available in your link. I have:
>> === Results Summary for run: run_01 tag: tag_1 ===
>> Cross-section : 5.543 +- 0.01578 pb
>> Nb of events : 10000
>> Is that tarball up-to-date? I wanted to check the value of your coupling, but looks like that you do not have attach the related log.
>> Since I can not reproduce your result, I'm not sure what I can do.
>
> I copied the madevent tarball from the directory itself, but looks like
> you are getting something sensible, while I don't... But did you replace
> the param_card and run_card first with the ones I provided in the dir
> itself ?
>
>
> Regards
>
> Alexis
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

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