"No amplitudes" error when setting MadSpin spinmode to full

Asked by Chris on 2017-07-31

I am using a Pseudoscalar_2HDM model to simulate dark matter + Z production, p p > xd xd~ z and then decaying the Z boson using MadSpin.
When MadSpin spinmode is set to full, it fails with the error:
"NoDiagramException: No amplitudes generated from process Process: g/d/u/s/c/d~/u~/s~/c~ g/d/u/s/c/d~/u~/s~/c~ > xd/xd~ xd/xd~ z WEIGHTED=12 @1. Please enter a valid process"

However, when spinmode is set to none, MadSpin executes without errors?

Do you know what causes this error, and how can I run in full spinmode?

Question information

Language:
English Edit question
Status:
Answered
For:
MadGraph5_aMC@NLO Edit question
Assignee:
No assignee Edit question
Last query:
2017-07-31
Last reply:
2017-10-18

Can you send me (via my email) your model and your cards.
Like this I do not see any reason why this happens (but if you use a very old version of the code)

Cheers,

Olivier

> On 31 Jul 2017, at 17:14, Chris <email address hidden> wrote:
>
> New question #654302 on MadGraph5_aMC@NLO:
> https://answers.launchpad.net/mg5amcnlo/+question/654302
>
> I am using a Pseudoscalar_2HDM model to simulate dark matter + Z production, p p > xd xd~ z and then decaying the Z boson using MadSpin.
> When MadSpin spinmode is set to full, it fails with the error:
> "NoDiagramException: No amplitudes generated from process Process: g/d/u/s/c/d~/u~/s~/c~ g/d/u/s/c/d~/u~/s~/c~ > xd/xd~ xd/xd~ z WEIGHTED=12 @1. Please enter a valid process"
>
> However, when spinmode is set to none, MadSpin executes without errors?
>
> Do you know what causes this error, and how can I run in full spinmode?
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

Chris (christopher-anelli) said : #2

Hi Olivier,

Thank you for your prompt response, I am not sure of your email so please
confirm that you receive this message.

I am running in MadGraph version 5.2.4.3, here are copies of the model,
cards, logfile, and debug file.

Best

Chris

On Mon, Jul 31, 2017 at 8:48 AM, Olivier Mattelaer <
<email address hidden>> wrote:

> Your question #654302 on MadGraph5_aMC@NLO changed:
> https://answers.launchpad.net/mg5amcnlo/+question/654302
>
> Status: Open => Answered
>
> Olivier Mattelaer proposed the following answer:
> Can you send me (via my email) your model and your cards.
> Like this I do not see any reason why this happens (but if you use a very
> old version of the code)
>
> Cheers,
>
> Olivier
>
> > On 31 Jul 2017, at 17:14, Chris <email address hidden>
> wrote:
> >
> > New question #654302 on MadGraph5_aMC@NLO:
> > https://answers.launchpad.net/mg5amcnlo/+question/654302
> >
> > I am using a Pseudoscalar_2HDM model to simulate dark matter + Z
> production, p p > xd xd~ z and then decaying the Z boson using MadSpin.
> > When MadSpin spinmode is set to full, it fails with the error:
> > "NoDiagramException: No amplitudes generated from process Process:
> g/d/u/s/c/d~/u~/s~/c~ g/d/u/s/c/d~/u~/s~/c~ > xd/xd~ xd/xd~ z WEIGHTED=12
> @1. Please enter a valid process"
> >
> > However, when spinmode is set to none, MadSpin executes without errors?
> >
> > Do you know what causes this error, and how can I run in full spinmode?
> >
> > --
> > You received this question notification because you are an answer
> > contact for MadGraph5_aMC@NLO.
>
> --
> If this answers your question, please go to the following page to let us
> know that it is solved:
> https://answers.launchpad.net/mg5amcnlo/+question/654302/+
> confirm?answer_id=0
>
> If you still need help, you can reply to this email or go to the
> following page to enter your feedback:
> https://answers.launchpad.net/mg5amcnlo/+question/654302
>
> You received this question notification because you asked the question.
>

Hi,

Your process is a loop-induced processes. MadSpin does not support loop-induced processes.
(This is actually why we introduced the mode spinmode none in order to still be able to decay such type of process)

Cheers,

Olivier

> On 31 Jul 2017, at 18:14, Chris <email address hidden> wrote:
>
> Question #654302 on MadGraph5_aMC@NLO changed:
> https://answers.launchpad.net/mg5amcnlo/+question/654302
>
> Status: Answered => Open
>
> Chris is still having a problem:
> Hi Olivier,
>
> Thank you for your prompt response, I am not sure of your email so please
> confirm that you receive this message.
>
> I am running in MadGraph version 5.2.4.3, here are copies of the model,
> cards, logfile, and debug file.
>
> Best
>
> Chris
>
> On Mon, Jul 31, 2017 at 8:48 AM, Olivier Mattelaer <
> <email address hidden>> wrote:
>
>> Your question #654302 on MadGraph5_aMC@NLO changed:
>> https://answers.launchpad.net/mg5amcnlo/+question/654302
>>
>> Status: Open => Answered
>>
>> Olivier Mattelaer proposed the following answer:
>> Can you send me (via my email) your model and your cards.
>> Like this I do not see any reason why this happens (but if you use a very
>> old version of the code)
>>
>> Cheers,
>>
>> Olivier
>>
>>> On 31 Jul 2017, at 17:14, Chris <email address hidden>
>> wrote:
>>>
>>> New question #654302 on MadGraph5_aMC@NLO:
>>> https://answers.launchpad.net/mg5amcnlo/+question/654302
>>>
>>> I am using a Pseudoscalar_2HDM model to simulate dark matter + Z
>> production, p p > xd xd~ z and then decaying the Z boson using MadSpin.
>>> When MadSpin spinmode is set to full, it fails with the error:
>>> "NoDiagramException: No amplitudes generated from process Process:
>> g/d/u/s/c/d~/u~/s~/c~ g/d/u/s/c/d~/u~/s~/c~ > xd/xd~ xd/xd~ z WEIGHTED=12
>> @1. Please enter a valid process"
>>>
>>> However, when spinmode is set to none, MadSpin executes without errors?
>>>
>>> Do you know what causes this error, and how can I run in full spinmode?
>>>
>>> --
>>> You received this question notification because you are an answer
>>> contact for MadGraph5_aMC@NLO.
>>
>> --
>> If this answers your question, please go to the following page to let us
>> know that it is solved:
>> https://answers.launchpad.net/mg5amcnlo/+question/654302/+
>> confirm?answer_id=0
>>
>> If you still need help, you can reply to this email or go to the
>> following page to enter your feedback:
>> https://answers.launchpad.net/mg5amcnlo/+question/654302
>>
>> You received this question notification because you asked the question.
>>
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

Andreas (balouderbaer) said : #4

Hi,

sorry to warm up this topic again, but I run into the same problem and wonder what the best solution for this case is.

If I understand correctly, "spinmode=None" is not a good solution since the physics of the Z->lepton decay will not be correct. I tried instead using "generate p p > xd xd~ l- l+", which seems to produce the diagrams I want. Will the spin info be handled correctly in this case? In any case, this solution is suboptimal as generation takes a very long time to run (>3 real days using >1k jobs on a condor cluster), which is very impractical.

Any advice would be appreciated!

Thanks

Andreas

Hi,

> If I understand correctly, "spinmode=None" is not a good solution since
> the physics of the Z->lepton decay will not be correct.

To be precise, you loose the spin-correlation effect (and off-shell effect of the Z mass).

> Will the spin info be handled correctly in this case?

Yes it will.

> In any
> case, this solution is suboptimal as generation takes a very long time
> to run (>3 real days using >1k jobs on a condor cluster), which is very
> impractical.

For Z-decay, the only solution that I can propose to you is then the
DECAY package that was present in MG5 version 1.x (and in MG4 version)
However, this module is not maintained anymore.

That package was keeping partial spin-correlation (so not the full spin-correlation but was keeping the diagonal part).
Using that package should allow you to have a huge gain in speed.

Cheers,

Olivier

> On 16 Oct 2017, at 15:03, Andreas <email address hidden> wrote:
>
> Question #654302 on MadGraph5_aMC@NLO changed:
> https://answers.launchpad.net/mg5amcnlo/+question/654302
>
> Andreas requested more information:
> Hi,
>
> sorry to warm up this topic again, but I run into the same problem and
> wonder what the best solution for this case is.
>
> If I understand correctly, "spinmode=None" is not a good solution since
> the physics of the Z->lepton decay will not be correct. I tried instead
> using "generate p p > xd xd~ l- l+", which seems to produce the diagrams
> I want. Will the spin info be handled correctly in this case? In any
> case, this solution is suboptimal as generation takes a very long time
> to run (>3 real days using >1k jobs on a condor cluster), which is very
> impractical.
>
> Any advice would be appreciated!
>
> Thanks
>
> Andreas
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

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