p p > l+ l- j with drll = 0.0 fail to reach target 1000

Asked by HaolinLi on 2018-02-03

Dear Madgraph Expert,

I encounter the problem for "fail to reach target 1000 " in the following process:

process p p > l+ l- j.

When I set the drll to zero then it takes very long time and did not get the number of events I set in the run_card.

I am using MG5_aMC_2_6_1. I initially suspect there are some divergent in this process, but I really cannot find

I really need the phase space for the two leptons are extremely close to each other.

Thanks,
Haolin

Question information

Language:
English Edit question
Status:
Solved
For:
MadGraph5_aMC@NLO Edit question
Assignee:
No assignee Edit question
Solved by:
Olivier Mattelaer
Solved:
2018-02-03
Last query:
2018-02-03
Last reply:
2018-02-03

Hi,

It is indeed divergent. That's a collinear divergence related to the photon propagator.

So this can not be done at fix order and you have to trust the parton-shower for such regime.

Cheers,

Olivier

> On 3 Feb 2018, at 03:37, HaolinLi <email address hidden> wrote:
>
> New question #664009 on MadGraph5_aMC@NLO:
> https://answers.launchpad.net/mg5amcnlo/+question/664009
>
> Dear Madgraph Expert,
>
> I encounter the problem for "fail to reach target 1000 " in the following process:
>
> process p p > l+ l- j.
>
> When I set the drll to zero then it takes very long time and did not get the number of events I set in the run_card.
>
> I am using MG5_aMC_2_6_1. I initially suspect there are some divergent in this process, but I really cannot find
>
> I really need the phase space for the two leptons are extremely close to each other.
>
> Thanks,
> Haolin
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

HaolinLi (lihaolin1991) said : #2

Thanks Olivier Mattelaer, that solved my question.