Simple pyROOT notebook example using TLorentz Vectors

In [1]:
import ROOT

Welcome to JupyROOT 6.08/04

In [2]:
## f = ROOT.TFile.Open("mc_105986.ZZ.root")
## f = ROOT.TFile.Open("mc_147770.Zee.root")
f = ROOT.TFile.Open("http://opendata.atlas.cern/release/samples/MC/mc_147770.Zee.root")

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c = ROOT.TCanvas("testCanvas","a first way to plot a variable",800,600)

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t = f.Get("mini")

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h = ROOT.TH1F("variable","Example plot: Number of Leptons",4,0,4)

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h_Mll = ROOT.TH1F("h_Mll","Invariant mass of the two Leptons",50,0,200)

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for event in t:
"""This is the cut #1: request at least 2 leptons"""
if t.lep_n > 1:
"""Let's define one TLorentz vector for each, e.i. two vectors!"""
leadingLep = ROOT.TLorentzVector(t.lep_pt[0], t.lep_eta[0], t.lep_phi[0], t.lep_E[0])
secondLep  = ROOT.TLorentzVector(t.lep_pt[1], t.lep_eta[1], t.lep_phi[1], t.lep_E[1])

"""Next line does the addition of the two TLorentz vectors above and so,
we can ask the mass very easy"""

"""We devide the value of the combined vector by 1000 to get the value in GeV"""
mll = TL_ll.M()/1000.
h_Mll.Fill(mll,w)

print "Done!"

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"""Now les't plot the mass of the lepton-lepton system"""
h_Mll.Draw()
c.Draw()

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