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Rivet analyses reference
ATLAS_2010_S8817804
Inclusive jet cross section and di-jet mass and chi spectra at 7 TeV in ATLAS
Experiment: ATLAS (LHC 7TeV)
Inspire ID: 871366
Status: VALIDATED
Authors:
References:
Beams: p+ p+
Beam energies: (3500.0, 3500.0) GeV
Run details:
- pp QCD jet production with a minimum jet pT of 60 GeV (inclusive) or 30 GeV (di-jets) at 7 TeV.
The first jet cross section measurement made with the ATLAS detector at the LHC. Anti-kt jets with $R=0.4$ and $R=0.6$ are resconstructed within $|y|<2.8$ and above 60 GeV for the inclusive jet cross section plots. For the di-jet plots the second jet must have pT>30 GeV. Jet pT and di-jet mass spectra are plotted in bins of rapidity between $|y| = $ 0.3, 0.8, 1.2, 2.1, and 2.8. Di-jet $\chi$ spectra are plotted in bins of di-jet mass between 340 GeV, 520 GeV, 800 GeV and 1200 GeV.
Source code:
ATLAS_2010_S8817804.cc
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122 | // -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Tools/BinnedHistogram.hh"
#include "Rivet/Projections/FastJets.hh"
namespace Rivet {
/// @brief ATLAS inclusive jet pT spectrum, di-jet Mass and di-jet chi
class ATLAS_2010_S8817804: public Analysis {
public:
ATLAS_2010_S8817804() : Analysis("ATLAS_2010_S8817804")
{ }
private:
enum Alg { AKT4=0, AKT6=1 };
public:
void init() {
FinalState fs;
declare(fs, "FinalState");
declare(FastJets(fs, FastJets::ANTIKT, 0.6), "AntiKT06");
declare(FastJets(fs, FastJets::ANTIKT, 0.4), "AntiKT04");
double ybins[] = { 0.0, 0.3, 0.8, 1.2, 2.1, 2.8 };
double massBinsForChi[] = { 340, 520, 800, 1200 };
size_t ptDsOffset(0), massDsOffset(10), chiDsOffset(20);
for (size_t alg = 0; alg < 2; ++alg) {
for (size_t i = 0; i < 5; ++i) {
_pThistos[alg].addHistogram(ybins[i], ybins[i+1], bookHisto1D(i + 1 + ptDsOffset, 1, 1));
}
ptDsOffset += 5;
for (size_t i = 0; i < 5; ++i) {
_massVsY[alg].addHistogram(ybins[i], ybins[i+1], bookHisto1D(i + 1 + massDsOffset, 1, 1));
}
massDsOffset += 5;
for (size_t i = 0; i < 3; ++i) {
_chiVsMass[alg].addHistogram(massBinsForChi[i], massBinsForChi[i+1], bookHisto1D(i + 1 + chiDsOffset, 1, 1));
}
chiDsOffset += 3;
}
}
void analyze(const Event& evt) {
Jets jetAr[2];
jetAr[AKT6] = apply<FastJets>(evt, "AntiKT06").jetsByPt(30*GeV);
jetAr[AKT4] = apply<FastJets>(evt, "AntiKT04").jetsByPt(30*GeV);
// Identify the dijets
for (size_t alg = 0; alg < 2; ++alg) {
vector<FourMomentum> leadjets;
foreach (const Jet& jet, jetAr[alg]) {
const double pT = jet.pT();
const double absy = jet.absrap();
_pThistos[alg].fill(absy, pT/GeV, evt.weight());
if (absy < 2.8 && leadjets.size() < 2) {
if (leadjets.empty() && pT < 60*GeV) continue;
leadjets.push_back(jet.momentum());
}
}
// Veto if no acceptable dijet found
if (leadjets.size() < 2) {
MSG_DEBUG("Could not find two suitable leading jets");
continue;
}
const double rap1 = leadjets[0].rapidity();
const double rap2 = leadjets[1].rapidity();
const double mass = (leadjets[0] + leadjets[1]).mass();
const double ymax = max(fabs(rap1), fabs(rap2));
const double chi = exp(fabs(rap1 - rap2));
if (fabs(rap1 + rap2) < 2.2) {
_chiVsMass[alg].fill(mass/GeV, chi, evt.weight());
}
_massVsY[alg].fill(ymax, mass/GeV, evt.weight());
}
}
void finalize() {
for (size_t alg = 0; alg < 2; ++alg) {
// factor 0.5 needed because it is differential in dy and not d|y|
_pThistos[alg].scale(0.5*crossSectionPerEvent()/picobarn, this);
_massVsY[alg].scale(crossSectionPerEvent()/picobarn, this);
_chiVsMass[alg].scale(crossSectionPerEvent()/picobarn, this);
}
}
private:
/// The inclusive pT spectrum for akt6 and akt4 jets (array index is jet type from enum above)
BinnedHistogram<double> _pThistos[2];
/// The di-jet mass spectrum binned in rapidity for akt6 and akt4 jets (array index is jet type from enum above)
BinnedHistogram<double> _massVsY[2];
/// The di-jet chi distribution binned in mass for akt6 and akt4 jets (array index is jet type from enum above)
BinnedHistogram<double> _chiVsMass[2];
};
// The hook for the plugin system
DECLARE_RIVET_PLUGIN(ATLAS_2010_S8817804);
}
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