From a new stable particle to missing energy in MG/Pythia/Delphes

[Maikel]

Hello all,

Let's say I have a stable particle in my new model, which I have. Which would then if produced in some process correspond to missing transverse energy after it has been processed in the MG/Pythia/Delphes chain. However if I check the missing transverse energy of these events, there is obviously something missing.

So how do I tell Pythia and Delphes this new particle corresponds to missing transverse energy?

Please note that I have been directed here by the MG team:

​https://answers.launchpad.net/madgraph5/+question/222285

Thanks in advance, Maikel

[Michele Selvaggi]

Hi Maikel,

can you check which PID is given by default to your particle by Pythia/MG?
Also, could you please upload somewhere a small event sample in *.hep and *.lhe formats so we can have a look. These should be both produced by default in the MG/ME/Pythia chain.

Michele

Replying to Maikel:

Hello all,

Let's say I have a stable particle in my new model, which I have. Which would then if produced in some process correspond to missing transverse energy after it has been processed in the MG/Pythia/Delphes chain. However if I check the missing transverse energy of these events, there is obviously something missing.

So how do I tell Pythia and Delphes this new particle corresponds to missing transverse energy?

Please note that I have been directed here by the MG team:

​https://answers.launchpad.net/madgraph5/+question/222285

Thanks in advance, Maikel

[Maikel]

Hello Michele,

The default id is 9000001 I uploaded the two event samples as required for the production

generate p p > wh+ zh, (wh+ > ah w+, w+ > l+ vl), (zh > ah h, h > b b~)

where ah is the guy. I now provided the Pythia/MG outputs, if you need others please contact me.

Thanks, Maikel

P.S. I also have problems with the b tagging efficiencies for this process, which do not seem to work.

[Michele Selvaggi]

Replying to Maikel:

Hi,

I don't see any attachment.. Maybe it is better if you could send ~50-100 events, so I can check better what you say about b-tagging.

Cheers,

Michele

[Maikel]

Sorry, there was some delay cause I think, pythia causes the problem...

Here are the events.

Best, Maikel

[Pavel Demin]

Hi,

I think that in case of Delphes 3.x adding the following line to the Calorimeter configuration could solve the problem

  add EnergyFraction {9000001} {0.0 0.0}

[Maikel]

Is it possible to make Delphes 3.0.0 compatible with MadGraph 1.5.7 easily?

[Michele Selvaggi]

Replying to Maikel:

Is it possible to make Delphes 3.0.0 compatible with MadGraph 1.5.7 easily?

Hi Maikel,

Delphes3 is not yet integrated in the MG framework. You should run it standalone.

It seems that there is a problem with your MG events. All the new particle (both the stables and unstables) seem to have pid=0, and mass=0 (however the spatial components are non zero). You can see that in the lhe file you sent.

I suggest you fix this issue first with MG5.

However, if you want a quick and dirty solution just add the line in Delphes.cpp:
pid = (pid >0)? pid : 9000001;
just after the line:
int pid = abs(particle->PID);

Don't forget to recompile delphes after that (just type make in delphes directory)

Cheers,

Michele

[Maikel]

Hello Michele (and pavel)

Thanks for this explanation, so if I get it correctly it is the pythia.lhe file Delphes needs?

The problem however seems to be with Pythia rather than MadGraph, and I don't see those particles with id=0 being massless, they seem to have the correct masses.

Any suggestions regarding the b tagging problems? If I increase the tagging efficiency I don't see an increase in the number of b jets, even though all b's are more or less central abs(eta) < 2.5.

Thanks, Maikel

[Michele Selvaggi]

Hi Maikel,

you're right, the MG file looks correct. The problem is with pythia. I think you should address this question to the mg5 or pythia developers.

If you apply that change I mentioned in the previous mail the b-tagging looks correct. Just change in data/DetectorCard_X.dat
BTAG_func_b 0.4+0*x+0*y
into
BTAG_func_b 0.9+0*x+0*y

and you should see increase the number of btagged jets.

Cheers,

Michele

Replying to Maikel:

Hello Michele (and pavel)

Thanks for this explanation, so if I get it correctly it is the pythia.lhe file Delphes needs?

The problem however seems to be with Pythia rather than MadGraph, and I don't see those particles with id=0 being massless, they seem to have the correct masses.

Any suggestions regarding the b tagging problems? If I increase the tagging efficiency I don't see an increase in the number of b jets, even though all b's are more or less central abs(eta) < 2.5.

Thanks, Maikel

[Johan Alwall]

Hello Maikel,

Please find the solution to your problem at
​https://answers.launchpad.net/madgraph5/+question/222285
The problem turned out to be in STDHEP, not in MadGraph, Pythia or Delphes.

And a comment: The pythia_events.lhe file is NOT the correct input to Delphes - as is made clear in many places, including the header of the file and ​https://cp3.irmp.ucl.ac.be/projects/madgraph/wiki/FAQ-General-9.
The file that is used is the pythia_events.hep file. In fact, the .lhe file format does not include all information needed for hadronized output (that is why there are the STDHEP and HEPMC formats), so COULD NOT be a meaningful input to Delphes.

All the best,
Johan

[Maikel]

Hello Johan,

I just saw that answer, thanks a lot, I am testing it now.

Yes, the .lhe file was just for seeing whether there was some problem with Pythia, thanks for the clarification though!

Best, Maikel

[mattelaer]

Hi Michele,

Concerning the b-tagging, Maikel reported that the value of the b-tagging is not read from the delphes_card . Is this expected? Is this due to the fact that MG is still using old style format for the delphes_card? Or did you just not taking care of those parameter in the card?

Cheers,

Olivier

[Michele Selvaggi]

Hi Olivier and Maikel,

Maikel, could you send us the Delphes card that is actually used?
What you showed seems different than the default delphes card.

Thanks

Michele

Replying to mattelaer:

Hi Michele,

Concerning the b-tagging, Maikel reported that the value of the b-tagging is not read from the delphes_card . Is this expected? Is this due to the fact that MG is still using old style format for the delphes_card? Or did you just not taking care of those parameter in the card?

Cheers,

Olivier

[Maikel]

I attached the delphes card in the Cards directory, I don't know if this is what you meant.

Best, Maikel

[Michele Selvaggi]

Hi Maikel,

sorry for late reply. So apparently MG is taking by delfault a detector card which is not the correct one. We will fix this with the MG/ME developers. Consider anyway moving to delphes 3 in the near future as delphes2 will get obsolete soon.

In the meantime, in order to fix the b-tagging problem I suggest you do one of the two following things:

• either run delphes standalone
• or change in the detector card the following lines:

# Tagging definition
BTAG_b 40 b-tag efficiency (%)
BTAG_mistag_c 10 mistagging (%)
BTAG_mistag_l 1 mistagging (%)

into:

BTAG_func_b 0.4+0*x+0*y formula for Pt dependence of the b-tag efficiency (b-jets)
BTAG_func_c 0.1+0*x+0*y formula for Pt dependence of the mistag efficiency (c-jets)
BTAG_func_g 0.01+0*x+0*y (gluon-jets)
BTAG_func_l 0.01+0*x+0*y (light-jets)

Michele

Replying to Maikel:

I attached the delphes card in the Cards directory, I don't know if this is what you meant.

Best, Maikel

[Johan Alwall]

Hello Michele,

Indeed we haven't upgraded the Delphes cards since the original v. 1.X ones. We'll make sure to do this in a coming release (once we get Delphes 2 or 3 to compile on Mac ;-)).

All the best,
Johan

[Maikel]

Hello both,

Thanks for clearing that up and posting a work around.

Best, Maikel