TLorentz Vector decleration of Electron and Muon

[ahmed hammad]

Hi Delphes Team
iam trying to construct tolrentz vector for electron or muon , As you know, i need four component : pt , eta , phi , energy ..
in fact the first three component are allowed in the delphes tree but the fourth one "energy" doesnt exist .. so , how can i overcome this ????
thanks
ahmed

[Michele Selvaggi]

Hi Ahmed,

if you are using root you can simply use the TLorentzVector method called SetPtEtaPhiM, and plug in the e/mu mass as the last entry.

Michele

[ahmed hammad]

Hi dr Michele
yes iam using root .
if you forgive my low information , there is no abranch for e or mu mass in delphes tree .
Ahmed

[Michele Selvaggi]

you'll have to put them by hand, these values are not stored in the tree:

in GeV
muon mass 0.105658389
electron mass 0.000510998902

[ahmed hammad]

Thanks alot , i really apperciate your help . this solves my problem
but ,there is another inquery .
i simulate BMS process with finale state 4 quarks > came from two W decay .
the out put from delphes delete alot of them , so i found almost less than 4 jets finale state per each event , the problem was in the delphes cut for jets , when i comment Pt jet cut , it giives me resonable results , but still very small number of events with finale state jets less than four .. i found that there is a cut in Fast jet modules pt cut = 10 Gev .
1- if i comment this cut it might be harm the analysis ??
2- how i know the threshold cut required ??
Ahmed

[Michele Selvaggi]

Hi Ahmed,

I am not sure how it is you find less, one of them might be escape the detector acceptance, or simply is not reconstructed.
There should be nothing wrong with that.

I suggest you keep the code like this. The jet threshold in the card will indeed control the final jet multiplicity.
In LHC experiments this is typically 20-30 GeV nowadays. If you need realistic cuts, I suggest you look for similar analysis in CMS or ATLAS
and get an idea from there.

Michele

[ahmed hammad]

Hi dr Michele
what do you meannt by not constructed ????
do you mean that these jets didnt pass the cuts and condition in delphes card or the problem is in Fast jet???
thanks
Ahmed

[Michele Selvaggi]

Hi Ahmed,

both things can happen. There is nothing wrong with fastjet, what I mean is it can simply happen that a parton doesn't give rise to a jet.
To check this you can look at how often, for each gen parton, you find a reconstructed jet within some cone of size:
DR = sqrt( ( phi(parton)-phi(jet) )^{2 +} ( eta(parton)-eta(jet) )² ) < 0.2 for instance.

Michele