fail to reach target

Asked by Antonios Leisos on 2018-04-25

Hello,
I am using MG5_aMC_v2_6_1 for the generation of VBS process
generate p p > z z j j QED=4 QCD=0 NP=1, (z > l+ l-)
with the LT012 Ufo model and anomalous quartic coupling
FT0=1E-12
When i request a sample i.e 10,000 events only a subset is generated (<1000).
The program informs that "fail to reach target.."
The largest set of events was approximately 12500 events when i requested 1,000,000 events.
When the anomalous coupling is 0 or up to 0.4E-12 the events are generated as requested.
Is there a way to overcome this?
Can we trust the events that are generated so as to combine small sets to a bigger one?

Thanks in advance,
Antonios

Question information

Language:
English Edit question
Status:
Solved
For:
MadGraph5_aMC@NLO Edit question
Assignee:
No assignee Edit question
Solved by:
Olivier Mattelaer
Solved:
2018-04-30
Last query:
2018-04-30
Last reply:
2018-04-25

Hi,

One thing that you should try is to check if you can optimise your model to avoid such type of problem:
https://answers.launchpad.net/mg5amcnlo/+faq/2312

Also version 2.6.2 (which should be released this week) might improve the situation.
At the same time, those are issue that we have since years and even if 2.6.2 improves the situation
this typically still fails to reach target for such kind of process. (but for the test that I did, it was generating 3 times more events in such cases)

When you do not reach the event target, your sample might be slightly bias (a small effect but ok).
So to be 100% sure, I would suggest that you reduce the amount of events that you ask.
(in 2.6.2 asking 2500 events should reach target) and then you should be able to combine them in a fully save way.

Cheers,

Olivier

On 25 Apr 2018, at 08:27, Antonios Leisos <<email address hidden><mailto:<email address hidden>>> wrote:

New question #668239 on MadGraph5_aMC@NLO:
https://answers.launchpad.net/mg5amcnlo/+question/668239

Hello,
I am using MG5_aMC_v2_6_1 for the generation of VBS process
generate p p > z z j j QED=4 QCD=0 NP=1, (z > l+ l-)
with the LT012 Ufo model and anomalous quartic coupling
FT0=1E-12
When i request a sample i.e 10,000 events only a subset is generated (<1000).
The program informs that "fail to reach target.."
The largest set of events was approximately 12500 events when i requested 1,000,000 events.
When the anomalous coupling is 0 or up to 0.4E-12 the events are generated as requested.
Is there a way to overcome this?
Can we trust the events that are generated so as to combine small sets to a bigger one?

Thanks in advance,
Antonios

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Antonios Leisos (leisos) said : #2

Hello Olivier,
the first solution you proposed worked for me. When i ask for 1000 events, I get 1000 events.
I am checking the second option as well.

Thanks again,
Antonios

Antonios Leisos (leisos) said : #3

Thanks Olivier Mattelaer, that solved my question.