Impact parameters with madanalysis

Asked by Anastasia on 2019-06-26

Dear MadAnalysis team,

I am facing the following problem while trying to generate some events with the long-lived particles:

I pair produce new charged particles (pdg id 9000007) which travel for some time and then decay to 9000005, a lepton and a corresponding neutrino.

I generate events with ./bin/generate_events --laststep = delphes command. Then I analyze the root file with madanalysis trying to get d0 for the reconstructed particles. The problem is that all the displaced parameters appear to be zero.

I am choosing particles by using the example for the reconstucted objects:

  for (MAuint32 i=0;i<event.rec()->electrons().size();i++)
    {
       const RecLeptonFormat& elec = event.rec()->electrons()[i];

and then all the parameters elec.d0(), elec.dz(), elec.closestPoint().X(), elec.vertexProd().X() (and same for Y and Z) are zero.

However, when I look at the hepmc file produced by pythia it seems that there are displaced leptons in the process. Here are two examples for a muon and an electron in the final state:

V -102 0 9.7530143008293838e-02 -1.0162510869114616e-01 1.1610691648837741e-01 4.5502877235197436e-01 0 3 0
P 136 9000005 7.0990167247589980e+01 -8.4888505568698747e+01 7.4517117883557688e+01 3.3290158145433890e+02 3.0499999975999998e+02 1 0 0 0 0
P 137 13 8.3207121329457259e+00 3.5500295989894259e+00 1.3467707399544571e+01 1.6224280174738070e+01 1.0566000000000000e-01 23 0 0 -103 0
P 138 -14 -3.4602022532881866e+00 2.3030816838613677e+00 2.3132914139043366e+00 4.7569425098314868e+00 0 23 0 0 -104 0

V -247 0 -5.2744060890782196e-01 4.5300201065806778e-01 3.3618765788469798e+00 4.4541323463706339e+00 0 3 0
P 319 9000005 -6.7694343820110959e+01 5.2610023593716846e+01 3.7103403787141571e+02 4.8789506646463849e+02 3.0499999975999998e+02 1 0 0 0 0
P 320 11 3.5023106875588361e+00 5.9806155730972668e+00 1.0532648666695152e+01 1.2608355601842716e+01 5.1099999999999995e-04 23 0 0 -248 0
P 321 -12 3.9449769809103281e+00 -6.8463534469812677e+00 2.4446383432284708e+00 8.2711338720932037e+00 0 23 0 0 -249 0

Am I doing something wrong with the analysis or the problem with delphes (if I understand correctly, using madanalysis I can extract d0 and other variables only from delphes output since these functions exist only for RecLeptonFormat-type objects)?

Of course, I am happy to provide you with any additional information needed. I use madanalysis 1.8.5, delphes 3.4.1.
Thank a lot!

Question information

Language:
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Status:
Answered
For:
MadAnalysis 5 Edit question
Assignee:
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Last query:
2019-06-30
Last reply:
2019-07-01

This question was reopened

Don't know how I can help you with on this topic...

Are you sure that d0 is the parameter that you are looking for (I thought that was a collision parameter distance which is used when someone simulates pile-up but I can be wrong on that)

Also did you request MG5aMC to include displaced vertex information? By default this is not include.

Cheers,

Olivier

Anastasia (assimptota) said : #2

Dear Oliver,

Indeed, I am looking for the impact parameter, which is included in madanalysis (the d0 one is listed, for example, in the reference card for the expert mode here https://madanalysis.irmp.ucl.ac.be/ ) for reconstructed leptons. It is defined as the transverse distance of closest approach of the track to the primary vertex point.

I did not include the displaced vertex info to MG5aMC because I apply the analysis to the reconstructed by delphes events, with pythia in between. And from the pythia output I can see that it does produce displaced vertices.

However, maybe it could help... How would you recommend to include the displacement to MG5aMC? I did add 1e-5 = time_of_flight to the run card, is there any other handle?

Cheers,
Anastasia

Hi,

Yes this is the only parameter at MG5aMC level.
For the rest of your setup (pythia, Delphes, MadAnalysis)
I would suggest to contact the associated authors. I will not be able to comment on that.

Cheers,

Olivier

Anastasia (assimptota) said : #4

Hi,

Thanks a lot.

Benjamin Fuks (fuks) said : #5

Dear Anastasia,

You need to use a more recent version of madanalysis 5 to have access to the displacement parameters.

Regards,

Benjamin

> On 27 Jun 2019, at 13:47 , Anastasia <email address hidden> wrote:
>
> Question #681607 on MadAnalysis 5 changed:
> https://answers.launchpad.net/madanalysis5/+question/681607
>
> Project: MadGraph5_aMC@NLO => MadAnalysis 5
>
> --
> You received this question notification because you are an answer
> contact for MadAnalysis 5.

Anastasia (assimptota) said : #6

Hi Benjamin,

Thanks for the reply. I am a little bit confused now since I think that I'm using the most recent one... The one I mentioned was installed with madgraph and the version is dated as:

Date : 2019/04/04
Time : 22:31:38
MA5 version : 1.8.5

I've also tried to install the newest madanalysis version separately, and there I faced the same problem. Actually, the current version here https://launchpad.net/madanalysis5 seems to be older:

Date : 2019/02/13
Time : 12:22:50
MA5 version : 1.7.21

and the file RecLeptonFormat.h in version 1.7.21 contains only d0 among the functions I listed (on the contrary, in version 1.85 functions dz(), closestPoint() and vertexProd() are also present).

Did you mean yet newer version? Am I missing the latest release?

Cheers,
Anastasia

Benjamin Fuks (fuks) said : #7

Dear Anastacia,

This is not the most recent one. Please try with
  https://code.launchpad.net/~ma5dev/madanalysis5/v1.8_beta <https://code.launchpad.net/~ma5dev/madanalysis5/v1.8_beta>

Cheers,

Benjamin

> On 30 Jun 2019, at 18:12 , Anastasia <email address hidden> wrote:
>
> Question #681607 on MadAnalysis 5 changed:
> https://answers.launchpad.net/madanalysis5/+question/681607
>
> Status: Solved => Open
>
> Anastasia is still having a problem:
> Hi Benjamin,
>
> Thanks for the reply. I am a little bit confused now since I think that
> I'm using the most recent one... The one I mentioned was installed with
> madgraph and the version is dated as:
>
> Date : 2019/04/04
> Time : 22:31:38
> MA5 version : 1.8.5
>
> I've also tried to install the newest madanalysis version separately,
> and there I faced the same problem. Actually, the current version here
> https://launchpad.net/madanalysis5 seems to be older:
>
> Date : 2019/02/13
> Time : 12:22:50
> MA5 version : 1.7.21
>
> and the file RecLeptonFormat.h in version 1.7.21 contains only d0 among
> the functions I listed (on the contrary, in version 1.85 functions dz(),
> closestPoint() and vertexProd() are also present).
>
> Did you mean yet newer version? Am I missing the latest release?
>
> Cheers,
> Anastasia
>
> --
> You received this question notification because you are an answer
> contact for MadAnalysis 5.

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