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D0_2008_S6879055.cc
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D0_2008_S6879055.cc
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// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/RivetAIDA.hh"
#include "Rivet/Tools/Logging.hh"
#include "Rivet/Projections/FinalState.hh"
#include "Rivet/Projections/LeadingParticlesFinalState.hh"
#include "Rivet/Projections/InvMassFinalState.hh"
#include "Rivet/Projections/VetoedFinalState.hh"
#include "Rivet/Projections/FastJets.hh"
namespace Rivet {
/// @brief D0 measurement of the ratio \f$ \sigma(Z/\gamma^* + n \text{ jets})/\sigma(Z/\gamma^*) \f$
class D0_2008_S6879055 : public Analysis {
public:
/// Default constructor.
D0_2008_S6879055() : Analysis("D0_2008_S6879055")
{
setBeams(PROTON, ANTIPROTON);
}
/// @name Analysis methods
//@{
// Book histograms
void init() {
// Basic final state
FinalState fs(-5.0, 5.0);
addProjection(fs, "FS");
// Leading electrons in tracking acceptance
LeadingParticlesFinalState lpfs(FinalState(-1.1, 1.1, 25*GeV));
lpfs.addParticleId(ELECTRON).addParticleId(POSITRON);
addProjection(lpfs, "LeadingElectronsFS");
// Invariant mass selection around Z pole
InvMassFinalState electronsFromZ(lpfs, make_pair(ELECTRON, POSITRON), 75*GeV, 105*GeV);
addProjection(electronsFromZ,"ElectronsFromZ");
// Vetoed FS for jets
VetoedFinalState vfs(fs);
// Add particle/antiparticle vetoing
vfs.vetoNeutrinos();
// Veto the electrons from Z decay
vfs.addVetoOnThisFinalState(electronsFromZ);
addProjection(vfs, "JetFS");
// Jet finder
FastJets jets(vfs, FastJets::D0ILCONE, 0.5);
addProjection(jets, "Jets");
_crossSectionRatio = bookHistogram1D(1, 1, 1);
_pTjet1 = bookHistogram1D(2, 1, 1);
_pTjet2 = bookHistogram1D(3, 1, 1);
_pTjet3 = bookHistogram1D(4, 1, 1);
}
/// Do the analysis
void analyze(const Event& event) {
// Skip if the event is empty
const FinalState& fs = applyProjection<FinalState>(event, "FS");
if (fs.empty()) vetoEvent;
const double weight = event.weight();
// Find the Z candidates
const InvMassFinalState& invmassfs = applyProjection<InvMassFinalState>(event, "ElectronsFromZ");
// If there is no Z candidate in the FinalState, skip the event
if (invmassfs.particles().size() != 2) {
getLog() << Log::DEBUG << "No Z candidate found" << endl;
vetoEvent;
}
// Now build the list of jets on a FS without the electrons from Z
// Additional cuts on jets: |eta| < 2.5 and dR(j,leading electron) > 0.4
const JetAlg& jetpro = applyProjection<JetAlg>(event, "Jets");
const Jets jets = jetpro.jetsByPt(20.0*GeV);
vector<FourMomentum> finaljet_list;
foreach (const Jet& j, jets) {
const double jeta = j.momentum().eta();
const double jphi = j.momentum().phi();
if (fabs(jeta) > 2.5) continue;
FourMomentum e0 = invmassfs.particles()[0].momentum();
FourMomentum e1 = invmassfs.particles()[1].momentum();
const double e0eta = e0.pseudorapidity();
const double e0phi = e0.azimuthalAngle();
if (deltaR(e0eta, e0phi, jeta, jphi) < 0.4) continue;
const double e1eta = e1.pseudorapidity();
const double e1phi = e1.azimuthalAngle();
if (deltaR(e1eta, e1phi, jeta, jphi) < 0.4) continue;
// If we pass all cuts...
finaljet_list.push_back(j.momentum());
}
getLog() << Log::DEBUG << "Num jets passing = " << finaljet_list.size() << endl;
// For normalisation of crossSection data (includes events with no jets passing cuts)
_crossSectionRatio->fill(0, weight);
// Fill jet pT and multiplicities
if (finaljet_list.size() >= 1) {
_crossSectionRatio->fill(1, weight);
_pTjet1->fill(finaljet_list[0].pT(), weight);
}
if (finaljet_list.size() >= 2) {
_crossSectionRatio->fill(2, weight);
_pTjet2->fill(finaljet_list[1].pT(), weight);
}
if (finaljet_list.size() >= 3) {
_crossSectionRatio->fill(3, weight);
_pTjet3->fill(finaljet_list[2].pT(), weight);
}
if (finaljet_list.size() >= 4) {
_crossSectionRatio->fill(4, weight);
}
}
/// Finalize
void finalize() {
// Now divide by the inclusive result
_crossSectionRatio->scale(1.0/_crossSectionRatio->binHeight(0));
// Normalise jet pTs to integrals of data
// NB. There is no other way to do this, because these quantities are not
// detector-corrected
normalize(_pTjet1, 10439.0); // fixed norm OK
normalize(_pTjet2, 1461.5); // fixed norm OK
normalize(_pTjet3, 217.0); // fixed norm OK
}
//@}
private:
/// @name Histograms
//@{
AIDA::IHistogram1D * _crossSectionRatio;
AIDA::IHistogram1D * _pTjet1;
AIDA::IHistogram1D * _pTjet2;
AIDA::IHistogram1D * _pTjet3;
//@}
};
// This global object acts as a hook for the plugin system
AnalysisBuilder<D0_2008_S6879055> plugin_D0_2008_S6879055;
}

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