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Rivet analyses reference
D0_2008_S6879055
Measurement of the ratio $\sigma(Z/\gamma^* + n \text{ jets})/\sigma(Z/\gamma^*)$
Experiment: D0 (Tevatron Run 2)
Inspire ID: 724239
Status: VALIDATED
Authors:
- Giulio Lenzi
- Frank Siegert
References:
Beams: p- p+
Beam energies: (980.0, 980.0) GeV
Run details:
- $p \bar{p} \to e^+ e^-$ + jets at 1960 GeV. Needs mass cut on lepton pair to avoid photon singularity, looser than $75 < m_{ee} < 105$ GeV.
Cross sections as a function of $p_\perp$ of the three leading jets and $n$-jet cross section ratios in $p \bar{p}$ collisions at $\sqrt{s}$ = 1.96 TeV, based on an integrated luminosity of $0.4 \text{fb}^{-1}$.
Source code:
D0_2008_S6879055.cc
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126 | // -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/ZFinder.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")
{ }
// DEFAULT_RIVET_ANA_CONSTRUCTOR(D0_2008_S6879055);
/// @name Analysis methods
//@{
// Book histograms
void init() {
FinalState fs;
ZFinder zfinder(fs, Cuts::open(), PID::ELECTRON,
40*GeV, 200*GeV, 0.2, ZFinder::CLUSTERNODECAY, ZFinder::TRACK);
declare(zfinder, "ZFinder");
FastJets conefinder(zfinder.remainingFinalState(), FastJets::D0ILCONE, 0.5);
declare(conefinder, "ConeFinder");
_crossSectionRatio = bookHisto1D(1, 1, 1);
_pTjet1 = bookHisto1D(2, 1, 1);
_pTjet2 = bookHisto1D(3, 1, 1);
_pTjet3 = bookHisto1D(4, 1, 1);
}
/// Do the analysis
void analyze(const Event& event) {
const double weight = event.weight();
const ZFinder& zfinder = apply<ZFinder>(event, "ZFinder");
if (zfinder.bosons().size()!=1) {
vetoEvent;
}
FourMomentum e0 = zfinder.constituents()[0].momentum();
FourMomentum e1 = zfinder.constituents()[1].momentum();
const double e0eta = e0.eta();
const double e0phi = e0.phi();
const double e1eta = e1.eta();
const double e1phi = e1.phi();
vector<FourMomentum> finaljet_list;
foreach (const Jet& j, apply<JetAlg>(event, "ConeFinder").jetsByPt(20*GeV)) {
const double jeta = j.eta();
const double jphi = j.phi();
if (fabs(jeta) < 2.5) {
if (deltaR(e0eta, e0phi, jeta, jphi) > 0.4 &&
deltaR(e1eta, e1phi, jeta, jphi) > 0.4) {
finaljet_list.push_back(j.momentum());
}
}
}
// 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
scale(_crossSectionRatio,1/_crossSectionRatio->bin(0).area());
// Normalise jet pTs to integrals of data
// @note There is no other way to do this, because these quantities are not detector-corrected
/// @todo Use integrals of refData()?
normalize(_pTjet1, 10439); // fixed norm OK
normalize(_pTjet2, 1461.5); // fixed norm OK
normalize(_pTjet3, 217); // fixed norm OK
}
//@}
private:
/// @name Histograms
//@{
Histo1DPtr _crossSectionRatio;
Histo1DPtr _pTjet1;
Histo1DPtr _pTjet2;
Histo1DPtr _pTjet3;
//@}
};
// The hook for the plugin system
DECLARE_RIVET_PLUGIN(D0_2008_S6879055);
}
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