bias module in LO-matching and NLO

Asked by Sung Hak Lim on 2017-04-21

Dear MG5 team,

I recently noticed that bias module is sometimes useful to study shallow tail of some kinematic distributions ( such as pt of leading jet ) .

In LO case, it looks working well as illustrated in https://cp3.irmp.ucl.ac.be/projects/madgraph/wiki/LOEventGenerationBias unless I set too high ptj_bias_enhancement_power, such as 10 instead of 4. I guess it is sort of floating point errors but I am not sure.

May I know this module is also implemented and tested with LO matching and NLO case? In wiki page, it only mentions LO case. I'm tracing back code and playing with it a bit but I want to make sure.

Best wishes,
Sung Hak Lim

Question information

Language:
English Edit question
Status:
Solved
For:
MadGraph5_aMC@NLO Edit question
Assignee:
No assignee Edit question
Solved by:
Olivier Mattelaer
Solved:
2017-04-21
Last query:
2017-04-21
Last reply:
2017-04-21

Dear Sung,

> I guess it is sort of floating point errors but I am not sure.

This can also be that you deform so much the function to integrate that the numerical method used to integrate fail to compensate.

> May I know this module is also implemented and tested with LO matching and NLO case? In wiki page, it only mentions LO case. I'm tracing back code and playing with it a bit but I want to make sure.

LO matching does not need a separate validation since this has the same effect as LO on the generation.
(Of course you need to be careful to check if it make sense to bias to high pt and doing at the same time matching but that is a physical issue not a technical one)

For NLO, this is not implemented.

Cheers,

Olivier
> On 21 Apr 2017, at 06:37, Sung Hak Lim <email address hidden> wrote:
>
> New question #625431 on MadGraph5_aMC@NLO:
> https://answers.launchpad.net/mg5amcnlo/+question/625431
>
> Dear MG5 team,
>
> I recently noticed that bias module is sometimes useful to study shallow tail of some kinematic distributions ( such as pt of leading jet ) .
>
> In LO case, it looks working well as illustrated in https://cp3.irmp.ucl.ac.be/projects/madgraph/wiki/LOEventGenerationBias unless I set too high ptj_bias_enhancement_power, such as 10 instead of 4. I guess it is sort of floating point errors but I am not sure.
>
> May I know this module is also implemented and tested with LO matching and NLO case? In wiki page, it only mentions LO case. I'm tracing back code and playing with it a bit but I want to make sure.
>
> Best wishes,
> Sung Hak Lim
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

Sung Hak Lim (sunghak-lim) said : #2

Thanks Olivier Mattelaer, that solved my question.