Rivet analyses
Pseudorapidity dependence of the total transverse energy at 7 TeV
Experiment: ATLAS (LHC 7TeV)
Inspire ID: 1183818
Status: VALIDATED
Authors: - Robindra Prabhu - Peter Wijeratne - Roman Lysak
References: - arXiv: 1208.6256
Beams: p+ p+
Beam energies: (3500.0, 3500.0)GeV
Run details: - pp QCD interactions at 7 TeV, min bias and di-jet events
The measurement of the sum of the transverse energy of particles as a function of particle pseudorapidity, eta, in proton-proton collisions at a centre-of-mass energy, $\sqrt{s} = 7~\TeV$ using the ATLAS detector at the Large Hadron Collider. The measurements are performed in the region |η| < 4.8 for two event classes: those requiring the presence of particles with a low transverse momentum and those requiring particles with a significant transverse momentum (dijet events where both jets have ET > 20 GeV). In the second dataset measurements are made in the region transverse to the hard scatter.
Source
code:ATLAS_2012_I1183818.cc
// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/ChargedFinalState.hh"
#include "Rivet/Projections/FastJets.hh"
#include "Rivet/Projections/FinalState.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((Cuts::etaIn(-4.8, 4.8)));
const ChargedFinalState cfs((Cuts::etaIn(-2.5, 2.5) && Cuts::pT >= 250 * MeV));
declare(cnfs, "FS");
declare(cfs, "CFS");
const FastJets jetsAntiKt4(cnfs, JetAlg::ANTIKT, 0.4);
declare(jetsAntiKt4, "AntiKt4Jets");
// ------- MINBIAS HISTOGRAMS --------
//
// MB event counter
book(m_chargedEvents, "m_chargedEvents_MB");
book(_h_ETflowEta, 1, 1, 1);
book(_h_SumETbin1, 3, 1, 1);
book(_h_SumETbin2, 4, 1, 1);
book(_h_SumETbin3, 5, 1, 1);
book(_h_SumETbin4, 6, 1, 1);
book(_h_SumETbin5, 7, 1, 1);
book(_h_SumETbin6, 8, 1, 1);
// ------- DIJET HISTOGRAMS --------
//
// Dijet event counter
book(m_events_dijets, "m_chargedEvents_dijets");
// sumET
book(_h_transETflowEta, 2, 1, 1);
book(_h_transSumETbin1, 9, 1, 1);
book(_h_transSumETbin2, 10, 1, 1);
book(_h_transSumETbin3, 11, 1, 1);
book(_h_transSumETbin4, 12, 1, 1);
book(_h_transSumETbin5, 13, 1, 1);
book(_h_transSumETbin6, 14, 1, 1);
}
void analyze(const Event& event) {
const FinalState& cfs = apply<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->fill();
}
const FinalState& cnfs = apply<FinalState>(event, "FS");
Particles particles;
for (const Particle& p : cnfs.particles()) {
// enforce truth selection representing detected particle sensitivity
double pp = p.p3().mod();
if (PID::charge3(p.pid()) != 0 && pp < 0.5 * GeV) continue;
if (PID::charge3(p.pid()) == 0 && pp < 0.2 * GeV) continue;
particles.push_back(p);
}
// get jets
const FastJets& jetsAntiKt4 = apply<FastJets>(event, "AntiKt4Jets");
const Jets& jets = jetsAntiKt4.jetsByPt(Cuts::pT > 20 * 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) {
for (const Particle& p : particles) {
///calculate variables
double ET = p.Et() / GeV;
double eta = p.abseta();
// fill histograms
_h_ETflowEta->fill(eta, 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 for
_h_SumETbin1->fill(sumETbin1);
_h_SumETbin2->fill(sumETbin2);
_h_SumETbin3->fill(sumETbin3);
_h_SumETbin4->fill(sumETbin4);
_h_SumETbin5->fill(sumETbin5);
_h_SumETbin6->fill(sumETbin6);
}
// --- do dijet analysis ---
if (jets.size() >= 2 && // require at least two jets
jets[0].Et() >= 20. * GeV && // require two leading jets to pass ET cuts
jets[1].Et() >= 20. * GeV && fabs(jets[0].eta()) < 2.5 && // require leading jets to be central
fabs(jets[1].eta()) < 2.5 && deltaPhi(jets[0], jets[1]) > 2.5 && // require back-to-back topology
jets[1].Et() / jets[0].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->fill();
// loop over all particles and check their relation to leading jet
for (const Particle& particle : particles) {
// calculate variables
double dPhi = deltaPhi(jets[0], particle.momentum());
double ET = particle.Et() / GeV;
double eta = fabs(particle.eta());
// Transverse region
if (dPhi > 1. / 3. * M_PI && dPhi < 2. / 3. * M_PI) {
_h_transETflowEta->fill(eta, 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);
_h_transSumETbin2->fill(trans_sumET_bin2);
_h_transSumETbin3->fill(trans_sumET_bin3);
_h_transSumETbin4->fill(trans_sumET_bin4);
_h_transSumETbin5->fill(trans_sumET_bin5);
_h_transSumETbin6->fill(trans_sumET_bin6);
} // 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->val() / (4. * M_PI));
scale(_h_SumETbin1, 1. / m_chargedEvents->val());
scale(_h_SumETbin2, 1. / m_chargedEvents->val());
scale(_h_SumETbin3, 1. / m_chargedEvents->val());
scale(_h_SumETbin4, 1. / m_chargedEvents->val());
scale(_h_SumETbin5, 1. / m_chargedEvents->val());
scale(_h_SumETbin6, 1. / m_chargedEvents->val());
//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->val() * 1. / (4. / 3. * M_PI));
scale(_h_transSumETbin1, 1. / m_events_dijets->val());
scale(_h_transSumETbin2, 1. / m_events_dijets->val());
scale(_h_transSumETbin3, 1. / m_events_dijets->val());
scale(_h_transSumETbin4, 1. / m_events_dijets->val());
scale(_h_transSumETbin5, 1. / m_events_dijets->val());
scale(_h_transSumETbin6, 1. / m_events_dijets->val());
}
private:
// Event counts
CounterPtr m_chargedEvents;
CounterPtr 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;
};
RIVET_DECLARE_PLUGIN(ATLAS_2012_I1183818);
}