Madgraph VERSION 2.7.2 unable to generate the targetted number of events

Did you try with more recent version?
A lot of improvement have been done on that topic in 2.8.0 and even more 2.9.0

Cheers,

Olivier

Dear Oliver
I tried with the most recent version. But there is no improvement

Best
Ouseph

On Thu, Feb 9, 2023 at 4:26 AM Olivier Mattelaer <
<email address hidden>> wrote:

> Your question #705001 on MadGraph5_aMC@NLO changed:
> https://answers.launchpad.net/mg5amcnlo/+question/705001
>
> Status: Open => Answered
>
> Olivier Mattelaer proposed the following answer:
> Did you try with more recent version?
> A lot of improvement have been done on that topic in 2.8.0 and even more
> 2.9.0
>
> Cheers,
>
> Olivier
>
> --
> 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/705001/+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/705001
>
> You received this question notification because you asked the question.
>

What is the width of your axion for each cases?

Olivier

Dear Oliver,

The decay width is set as '0'.
Do I need to set it as the actual one for each mass according to the
analytical expression?

Best regards
Ouseph

On Thu, Feb 9, 2023 at 1:50 PM Olivier Mattelaer <
<email address hidden>> wrote:

> Your question #705001 on MadGraph5_aMC@NLO changed:
> https://answers.launchpad.net/mg5amcnlo/+question/705001
>
> Olivier Mattelaer posted a new comment:
> What is the width of your axion for each cases?
>
> Olivier
>
> --
> You received this question notification because you asked the question.
>

Dear Oliver,
I tried in that way too, But I am suffering the same problem with heavier
axion mass.
I tried for malp=1,10,100.

My full process is e+ e- > e+ e- ax / e+ e- p h, (ax > a a)

Best
Ouseph

On Thu, Feb 9, 2023 at 2:55 PM Olivier Mattelaer <
<email address hidden>> wrote:

> Your question #705001 on MadGraph5_aMC@NLO changed:
> https://answers.launchpad.net/mg5amcnlo/+question/705001
>
> Status: Open => Answered
>
> Olivier Mattelaer proposed the following answer:
> Hi,
>
> Your amplitude is divergeant if the width is set to zero and therefore it
> is impossible to generate events for the process.
> (and the cross-section will be wrong), so yes you have to put the correct
> value for the width.
>
> Cheers,
>
> Olivier
>
> --
> 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/705001/+confirm?answer_id=4
>
> 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/705001
>
> You received this question notification because you asked the question.
>

Dear Oliver,

I want to add one more piece of information.
I could successfully generate my targetted number of events for *e+ e- > e+
e- ax *for all mass ranges, The problem is coming only when I consider *e+
e- > e+ e- ax, ax > a a.*
I even tried *e+ e- > e+ e- ax, ax > a a. *by setting the decay of axion by
setting auto, Still I can't produce the targetted number of events for the
heavy alp masses

The latest madgraph version gives the following suggestions, I tried all
the following suggestions. But no results

failed to generate enough events. Please follow one of the following
suggestions to fix the issue: - set in the run_card.dat 'sde_strategy' to 3
- set in the run_card.dat 'hard_survey' to 1 or 2. - reduce the number of
requested events (if set too high) - check that you do not have
-integrable- singularity in your amplitude.

Best
Ouseph

On Thu, Feb 9, 2023 at 3:09 PM Melbin C.J. <email address hidden> wrote:

> Dear Oliver,
> I tried in that way too, But I am suffering the same problem with heavier
> axion mass.
> I tried for malp=1,10,100.
>
> My full process is e+ e- > e+ e- ax / e+ e- p h, (ax > a a)
>
> Best
> Ouseph
>
>
> On Thu, Feb 9, 2023 at 2:55 PM Olivier Mattelaer <
> <email address hidden>> wrote:
>
>> Your question #705001 on MadGraph5_aMC@NLO changed:
>> https://answers.launchpad.net/mg5amcnlo/+question/705001
>>
>> Status: Open => Answered
>>
>> Olivier Mattelaer proposed the following answer:
>> Hi,
>>
>> Your amplitude is divergeant if the width is set to zero and therefore it
>> is impossible to generate events for the process.
>> (and the cross-section will be wrong), so yes you have to put the correct
>> value for the width.
>>
>> Cheers,
>>
>> Olivier
>>
>> --
>> 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/705001/+confirm?answer_id=4
>>
>> 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/705001
>>
>> You received this question notification because you asked the question.
>>
>

Hi,

For the syntax "e+ e- > e+ e- ax, ax > a a " you are assuming the narrow-width approximation is valid.
So did you check if this is the case? The code will not be able to generate events for such syntax if that hyppothesis is not correct.

Cheers,

Olivier

Dear Oliver,
In my case, the narrow-width approximation is valid.

Best
Ouseph

On Fri, Feb 10, 2023 at 3:26 AM Olivier Mattelaer <
<email address hidden>> wrote:

> Your question #705001 on MadGraph5_aMC@NLO changed:
> https://answers.launchpad.net/mg5amcnlo/+question/705001
>
> Status: Open => Answered
>
> Olivier Mattelaer proposed the following answer:
> Hi,
>
> For the syntax "e+ e- > e+ e- ax, ax > a a " you are assuming the
> narrow-width approximation is valid.
> So did you check if this is the case? The code will not be able to
> generate events for such syntax if that hyppothesis is not correct.
>
> Cheers,
>
> Olivier
>
> --
> 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/705001/+confirm?answer_id=7
>
> 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/705001
>
> You received this question notification because you asked the question.
>

Hi,

I have tested the following script

import model ALP_linear_UFO_WIDTH
generate e+ e- > e+ e- ax, ax > a a
output
launch
set ma scan:[0.1,1,10,100]
set walp auto
set ptl 10
set pta 10
set cut_decays T
set etal 1.83
set etaa 2.4
set dral 0
set draa 0
set ebeam 125
set nevents 100k

(The model ALP_linear_UFO that i have on my laptop does not allow to change the width of the axion)

and the result is:

#run_name mass#9000005 cross width#9000005
run_01 1.000000e-01 7.259970e-38 7.165775e-10
run_02 1.000000e+00 6.288260e-38 7.178278e-07
run_03 1.000000e+01 1.770675e-35 7.282465e-04
run_04 1.000000e+02 3.193621e-37 7.164917e-01

and 100k events for each.
So I do not understand what your issue is. But I guess that the above script will help you to understand it.

Olivier

Dear Oliver,

My exact process is e+ e- > e+ e- ax / e+ e- h, ( ax > a a),
I solved the issue by putting the exact decay width at the ferrules level (
at the time of UFO building). You suggested this one in the previous email,
The issue was caused by the zero decay width of the particle that was
automatically set by MadGraph. By replacing the decay width of the particle
at the Feynrules level (at the beginning of model building), I was able to
generate the desired number of events.

Thank you very much
Best
Ouseph

On Fri, Feb 10, 2023 at 4:10 PM Olivier Mattelaer <
<email address hidden>> wrote:

> Your question #705001 on MadGraph5_aMC@NLO changed:
> https://answers.launchpad.net/mg5amcnlo/+question/705001
>
> Status: Open => Answered
>
> Olivier Mattelaer proposed the following answer:
> Hi,
>
> I have tested the following script
>
> import model ALP_linear_UFO_WIDTH
> generate e+ e- > e+ e- ax, ax > a a
> output
> launch
> set ma scan:[0.1,1,10,100]
> set walp auto
> set ptl 10
> set pta 10
> set cut_decays T
> set etal 1.83
> set etaa 2.4
> set dral 0
> set draa 0
> set ebeam 125
> set nevents 100k
>
> (The model ALP_linear_UFO that i have on my laptop does not allow to
> change the width of the axion)
>
> and the result is:
>
> #run_name mass#9000005 cross
> width#9000005
> run_01 1.000000e-01 7.259970e-38 7.165775e-10
> run_02 1.000000e+00 6.288260e-38 7.178278e-07
> run_03 1.000000e+01 1.770675e-35 7.282465e-04
> run_04 1.000000e+02 3.193621e-37 7.164917e-01
>
> and 100k events for each.
> So I do not understand what your issue is. But I guess that the above
> script will help you to understand it.
>
> Olivier
>
> --
> 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/705001/+confirm?answer_id=9
>
> 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/705001
>
> You received this question notification because you asked the question.
>

Thanks Olivier Mattelaer, that solved my question.