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ATLAS_2012_I1183818.cc
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ATLAS_2012_I1183818.cc
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// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/FinalState.hh"
#include "Rivet/Projections/ChargedFinalState.hh"
#include "Rivet/Projections/FastJets.hh"
/// @author Peter Wijeratne <paw@hep.ucl.ac.uk>
/// @author Robindra Prabhu <prabhu@cern.ch>
namespace Rivet {
// A very basic analysis sensitive to ET flow in minbias and dijet events
class ATLAS_2012_I1183818 : public Analysis {
public:
ATLAS_2012_I1183818()
: Analysis("ATLAS_2012_I1183818")
{}
public:
void init() {
const FinalState cnfs(-4.8, 4.8, 0*MeV);
const ChargedFinalState cfs(-2.5, 2.5, 250*MeV);
addProjection(cnfs, "FS");
addProjection(cfs, "CFS");
const FastJets jetsAntiKt4(cnfs, FastJets::ANTIKT, 0.4);
addProjection(jetsAntiKt4, "AntiKt4Jets");
// ------- MINBIAS HISTOGRAMS --------
//
// MB event counter
m_chargedEvents = 0.0;
_h_ETflowEta = bookHisto1D(1, 1, 1);
_h_SumETbin1 = bookHisto1D(3, 1, 1);
_h_SumETbin2 = bookHisto1D(4, 1, 1);
_h_SumETbin3 = bookHisto1D(5, 1, 1);
_h_SumETbin4 = bookHisto1D(6, 1, 1);
_h_SumETbin5 = bookHisto1D(7, 1, 1);
_h_SumETbin6 = bookHisto1D(8, 1, 1);
// ------- DIJET HISTOGRAMS --------
//
// Dijet event counter
m_events_dijets = 0.0;
// sumET
_h_transETflowEta = bookHisto1D( 2, 1, 1);
_h_transSumETbin1 = bookHisto1D( 9, 1, 1);
_h_transSumETbin2 = bookHisto1D(10, 1, 1);
_h_transSumETbin3 = bookHisto1D(11, 1, 1);
_h_transSumETbin4 = bookHisto1D(12, 1, 1);
_h_transSumETbin5 = bookHisto1D(13, 1, 1);
_h_transSumETbin6 = bookHisto1D(14, 1, 1);
}
void analyze(const Event& event) {
const double weight = event.weight();
const FinalState& cfs = applyProjection<FinalState>(event, "CFS");
bool isCharged = false;
if (cfs.size() >= 2) { // event selection: > 2 charged particles with pT > 250.MeV and |eta| < 2.5
isCharged = true;
m_chargedEvents += weight;
}
const FinalState& cnfs = applyProjection<FinalState>(event, "FS");
Particles particles;
foreach( const Particle& p, cnfs.particles() ) {
// enforce truth selection representing detected particle sensitivity
double pp = p.momentum().p().mod();
if (PID::threeCharge(p.pdgId()) != 0 && pp < 0.5*GeV) continue;
if (PID::threeCharge(p.pdgId()) == 0 && pp < 0.2*GeV) continue;
particles.push_back(p);
}
// get jets
const FastJets& jetsAntiKt4 = applyProjection<FastJets>(event, "AntiKt4Jets");
const Jets& jets = jetsAntiKt4.jetsByPt(20.0*GeV);
// initialise sumET variables
double sumETbin1 = 0;
double sumETbin2 = 0;
double sumETbin3 = 0;
double sumETbin4 = 0;
double sumETbin5 = 0;
double sumETbin6 = 0;
// if (passes event selection)
if (isCharged) {
foreach( const Particle& p, particles ) {
///calculate variables
double ET = p.momentum().Et()/GeV;
double eta = fabs(p.momentum().eta());
// fill histograms
_h_ETflowEta->fill(eta, weight*ET);
if (eta < 0.8) sumETbin1 += ET;
else if (eta < 1.6) sumETbin2 += ET;
else if (eta < 2.4) sumETbin3 += ET;
else if (eta < 3.2) sumETbin4 += ET;
else if (eta < 4.0) sumETbin5 += ET;
else if (eta <= 4.8) sumETbin6 += ET;
} // end of foreach
_h_SumETbin1->fill(sumETbin1, weight);
_h_SumETbin2->fill(sumETbin2, weight);
_h_SumETbin3->fill(sumETbin3, weight);
_h_SumETbin4->fill(sumETbin4, weight);
_h_SumETbin5->fill(sumETbin5, weight);
_h_SumETbin6->fill(sumETbin6, weight);
}
// --- do dijet analysis ---
if ( jets.size() >= 2 && // require at least two jets
jets[0].momentum().Et() >= 20.*GeV && // require two leading jets to pass ET cuts
jets[1].momentum().Et() >= 20.*GeV &&
fabs(jets[0].momentum().eta()) < 2.5 && // require leading jets to be central
fabs(jets[1].momentum().eta()) < 2.5 &&
deltaPhi(jets[0], jets[1]) > 2.5 && // require back-to-back topology
jets[1].momentum().Et()/jets[0].momentum().Et() >= 0.5) { //require ET-balance
// found an event that satisfies dijet selection, now fill histograms...
// initialise dijet sumET variables
double trans_sumET_bin1 = 0.;
double trans_sumET_bin2 = 0.;
double trans_sumET_bin3 = 0.;
double trans_sumET_bin4 = 0.;
double trans_sumET_bin5 = 0.;
double trans_sumET_bin6 = 0.;
m_events_dijets += weight;
// loop over all particles and check their relation to leading jet
foreach( const Particle& particle, particles ) {
// calculate variables
double dPhi = deltaPhi( jets[0], particle.momentum() );
double ET = particle.momentum().Et()/GeV;
double eta = fabs(particle.momentum().eta());
// Transverse region
if ( dPhi > 1./3.*M_PI && dPhi < 2./3.*M_PI ) {
_h_transETflowEta->fill( eta, weight*ET );
if (eta < 0.8) { trans_sumET_bin1 += ET; }
else if (eta < 1.6) { trans_sumET_bin2 += ET; }
else if (eta < 2.4) { trans_sumET_bin3 += ET; }
else if (eta < 3.2) { trans_sumET_bin4 += ET; }
else if (eta < 4.0) { trans_sumET_bin5 += ET; }
else if (eta <= 4.8) { trans_sumET_bin6 += ET; }
}
} // end loop over particles
_h_transSumETbin1->fill( trans_sumET_bin1, weight);
_h_transSumETbin2->fill( trans_sumET_bin2, weight);
_h_transSumETbin3->fill( trans_sumET_bin3, weight);
_h_transSumETbin4->fill( trans_sumET_bin4, weight);
_h_transSumETbin5->fill( trans_sumET_bin5, weight);
_h_transSumETbin6->fill( trans_sumET_bin6, weight);
} // end of dijet selection cuts
}
void finalize() {
/// several scale factors here:
/// 1. nEvents (m_chargedEvents)
/// 2. phase-space (2*M_PI)
/// 3. double binning due to symmetrisation (2)
scale( _h_ETflowEta, 1./m_chargedEvents/(4.*M_PI) );
scale( _h_SumETbin1, 1./m_chargedEvents );
scale( _h_SumETbin2, 1./m_chargedEvents );
scale( _h_SumETbin3, 1./m_chargedEvents );
scale( _h_SumETbin4, 1./m_chargedEvents );
scale( _h_SumETbin5, 1./m_chargedEvents );
scale( _h_SumETbin6, 1./m_chargedEvents );
//Dijet analysis
// Dijet scale factors:
//1. number of events passing dijet selection
//2. phase-space: 1. / 2/3*M_PI
//3. double binning due to symmetrisation in |eta| plots : 1/2
scale( _h_transETflowEta, 1./m_events_dijets * 1./(4./3.*M_PI) );
scale( _h_transSumETbin1, 1./m_events_dijets );
scale( _h_transSumETbin2, 1./m_events_dijets );
scale( _h_transSumETbin3, 1./m_events_dijets );
scale( _h_transSumETbin4, 1./m_events_dijets );
scale( _h_transSumETbin5, 1./m_events_dijets );
scale( _h_transSumETbin6, 1./m_events_dijets );
}
private:
// Event counts
double m_chargedEvents;
double m_events_dijets;
// Minbias-analysis: variable + histograms
Histo1DPtr _h_ETflowEta;
Histo1DPtr _h_SumETbin1;
Histo1DPtr _h_SumETbin2;
Histo1DPtr _h_SumETbin3;
Histo1DPtr _h_SumETbin4;
Histo1DPtr _h_SumETbin5;
Histo1DPtr _h_SumETbin6;
// Transverse region
Histo1DPtr _h_transETflowEta;
Histo1DPtr _h_transSumETbin1;
Histo1DPtr _h_transSumETbin2;
Histo1DPtr _h_transSumETbin3;
Histo1DPtr _h_transSumETbin4;
Histo1DPtr _h_transSumETbin5;
Histo1DPtr _h_transSumETbin6;
};
DECLARE_RIVET_PLUGIN(ATLAS_2012_I1183818);
}

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