fake lepton in Delphes 3.1.2

[andy]

Hi,

Some manual show that Delphes 3 does not consider the fake lepton (e and mu) from jet. However, I generate 40k events of p p > z > j j with madgraph, then automatically using pythia and Delphes 3.1.2. After analyzing the LHCO file, I obtain two e- (PT 10-30), one mu- (PT 10-20) and one mu+ (PT 40-50). Does the Delphes 3.1.2 used by madgraph consider the fake lepton? If not, where are the lepton from? How to modify the delphes3 to obtain the fake lepton (only need add a simple fake rate), could you give me some detailed introductions?

Best,

[Michele Selvaggi]

Hi Andy,

could you attach here a small event file in STDHEP format (the one produced by MG5 after hadronization), so we can have a look?

Thanks
Michele

[andy]

Dear Michele,
Thank you for your reply.

The HEP file is too big to upload. I use the Madanalysis5 to analyze the data. From the _pythia_events.hep.gz file, I find that the number of e-, e+, mu+ and mu- are respectively around 10^{7.
There is no lepton in the _pythia_events.lhe.gz file. Anything is wrong?}

Best,

[Michele Selvaggi]

Hi,

your *.lhe file should contain only hard scattering particles, hence Z, and quarks, so it is normal to have no leptons. Fake leptons are not simulated in Delphes, so if you have any they might be due to:

• semileptonic decays from heavy quark (very unlikely in your case unless you changed the definition of "j" in MadGraph)
• error in the conversion of the Delphes output from root to lhco format
• error somewhere in MadAnalysis

I need to have a small event sample to be sure that Delphes does what it is supposed to. Can't you generate a small 100 event sample and send the *.hep and *.lhe file?

If you send me the file I can try to run Delphes in standalone and apply lhco conversion to see if everything is fine. Also, which detector card are you using?

Michele

[andy]

Dear Michele,

I use 10000 events to get a fake e-. Sorry to obtain a fake lepton for enough events. I applied a dropbox,

Please download the lhco and hep files from the following website:
​https://www.dropbox.com/login

Email:andyandytev@yahoo.com
password:andy123456

Best,

[andy]

I indeed find a pdg=1 (in the 10407th line) in the LHCO file.

[andy]

I took j = g u c d s u~ c~ d~ s~.
If the electron is from the semileptonic decays from heavy quark, will Delphes treat it as a real electron not as fake electron? How to add a simple fake rate of lepton to Delphes?

[Michele Selvaggi]

Hi,

if the lepton passes isolation cuts then it will be considered as a prompt one, and that's a wanted behaviour. I am not surprised that in your final selection you end up with some lepton coming from semi-letponic heavy quark decay.

As said above, Delphes does not have fakes implemented. But it is fairly easy to implement a parametrized fake rate from jets to lepton. Is this what you want: a module that randomly creates "converts" jets into fake electrons as a function of the jet pt, eta?

What exactly do you want? We can guide you in the process, or even do it ourselves.

Cheers,
Michele

[andy]

Hi Michele,

“a module that randomly creates "converts" jets into fake electrons as a function of the jet pt, eta“， this is just what I want. However, I am a beginner of the delphes. If you could release the code of module and how to use it， it will be very perfect.

Many thanks,

Andy

[Ezequiel Alvarez]

Hi Michele,

I would also need to ramdonly convert a jet into a fake electron. From studying the Delphes card, and inspired in the b-tagging module, I would set the module as follows. Is this correct? Thanks in advance for the corrections, Ezequiel.

#####################
# Electron efficiency
#####################

module Efficiency ElectronEfficiency {

set InputArray ElectronEnergySmearing/electrons
set OutputArray electrons

# set EfficiencyFormula {efficiency formula as a function of eta and pt}

# efficiency formula for electrons
add EfficiencyFormula {21} {0.001}
add EfficiencyFormula {1} {0.001}
add EfficiencyFormula {2} {0.001}
add EfficiencyFormula {3} {0.001}
add EfficiencyFormula {4} {0.001}
add EfficiencyFormula {11} { (pt <= 10.0) * (0.00) + \

(abs(eta) <= 1.5) * (pt > 10.0) * (0.95) + \

(abs(eta) > 1.5 && abs(eta) <= 2.5) * (pt > 10.0) * (0.85) + \
(abs(eta) > 2.5) * (0.00)}

}