MadGraph5_aMC@NLO

MadGraph v2.8.3.2 fails to reach target number of events

Asked by Steven Jeremies

Hello,

I am trying to generate events for the process p p > b l+ vl b l- vl~ a. Like
other persons before me, I encountered the 'fail to reach target 10000' problem.
Like suggested in question #689230 I tried to use the run_card option hard_process
and set it on True but I was told this it is an invalid command.

The other options I chose where:

set no_parton_cut
set pta 15
set etaa 5
set etal 5
set drab 0.2
set draj 0.2
set dral 0.2

I try to avoid the collinear divergence through the pta setting. Are their other divergencies or problems related to my settings that I am missing? What happened to the hard_process option and what could be the reason for my shortage of events? Thanks in advance!

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MadGraph5_aMC@NLO Edit question
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Solved by:
Olivier Mattelaer
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Revision history for this message
Olivier Mattelaer (olivier-mattelaer) said : 		#1

Hi,

I have try the following sript:
import model sm
generate p p > b l+ vl b l- vl~ a
output
launch
set no_parton_cut
set pta 15
set etaa 5
set etal 5
set drab 0.2
set draj 0.2
set dral 0.2

but it crash with
NoDiagramException : No amplitudes generated from process Process: g/u/c/d/s/u~/c~/d~/s~ g/u/c/d/s/u~/c~/d~/s~ > b e+/mu+ ve/vm/vt b e-/mu- ve~/vm~/vt~ a WEIGHTED=14 @1. Please enter a valid process

So I'm not able to generate this without knowing which BSM model you are trying to simulate.

Cheers,

Olivier

Revision history for this message
Olivier Mattelaer (olivier-mattelaer) said : 		#2

In any case,
I would advise to check that your process is finite without the photon in the final state.
For your process, it would make sense to have cut on both the b-quark and on the lepton
such that you kill the divergency associated to
1. the gluon splitting into b b~ (even if the mass here helps)
2. the photon going to l+ l- (where I do not see how you prevent such divergency)

Cheers,

Olivier

> On 1 Aug 2022, at 15:50, Olivier Mattelaer <email address hidden> wrote:
>
> Question #702622 on MadGraph5_aMC@NLO changed:
> https://answers.launchpad.net/mg5amcnlo/+question/702622
>
> Status: Open => Answered
>
> Olivier Mattelaer proposed the following answer:
> Hi,
>
> I have try the following sript:
> import model sm
> generate p p > b l+ vl b l- vl~ a
> output
> launch
> set no_parton_cut
> set pta 15
> set etaa 5
> set etal 5
> set drab 0.2
> set draj 0.2
> set dral 0.2
>
> but it crash with
> NoDiagramException : No amplitudes generated from process Process: g/u/c/d/s/u~/c~/d~/s~ g/u/c/d/s/u~/c~/d~/s~ > b e+/mu+ ve/vm/vt b e-/mu- ve~/vm~/vt~ a WEIGHTED=14 @1. Please enter a valid process
>
> So I'm not able to generate this without knowing which BSM model you are
> trying to simulate.
>
> Cheers,
>
> Olivier
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

Revision history for this message
Steven Jeremies (minits) said : 		#3

Hi Olivier,

I am working with the 'sm-no_b_mass' model. So i still have collinear divergences just not for the photon but for the oher final state particles, right? And you suggest to put a cut to their transverse momentum as well?

Best,
Steven

Revision history for this message
Best Olivier Mattelaer (olivier-mattelaer) said : 		#4

> I am working with the 'sm-no_b_mass' model.

So I guess that you did a typo in your process since that process is also not possible in sm-no_b_mass.
Are you trying to generate
 p p > b l+ vl b~ l- vl~ a
instead of
 p p > b l+ vl b l- vl~ a?

> So i still have collinear
> divergences just not for the photon but for the oher final state
> particles, right?

Since your b is massless, I would expect that you have soft and collinear divergency for all particles (but the neutrino)
So yes you would need to add pt cut, rapidity cut and separation cut (in a way keep the default run_card should be enough)

Cheers,

Olivier

> On 1 Aug 2022, at 17:15, Steven Jeremies <email address hidden> wrote:
>
> Question #702622 on MadGraph5_aMC@NLO changed:
> https://answers.launchpad.net/mg5amcnlo/+question/702622
>
> Status: Answered => Open
>
> Steven Jeremies is still having a problem:
> Hi Olivier,
>
> I am working with the 'sm-no_b_mass' model. So i still have collinear
> divergences just not for the photon but for the oher final state
> particles, right? And you suggest to put a cut to their transverse
> momentum as well?
>
> Best,
> Steven
>
> --
> You received this question notification because you are an answer
> contact for MadGraph5_aMC@NLO.

Revision history for this message
Steven Jeremies (minits) said : 		#5

Thanks Olivier Mattelaer, that solved my question.