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## Rivet analyses reference

### ATLAS_2014_I1326641

3-jet cross section with 7 TeV data
Experiment: ATLAS (LHC)
Inspire ID: 1326641
Status: VALIDATED
Authors:
• Aliaksei Hrynevich
• Pavel Starovoitov
References:
Beams: p+ p+
Beam energies: (3500.0, 3500.0) GeV
Run details:
• QCD jet production with at least three leading jets

Double-differential three-jet production cross-sections have been measured in proton-proton collisions at a centre-of-mass energy of $\sqrt{s} = 7\,$TeV using the ATLAS detector at the Large Hadron Collider. The measurements are presented as a function of the three-jet mass ($m_{jjj}$), in bins of the sum of the absolute rapidity separations between the three leading jets ($\left|Y^\ast\right|$). Invariant masses extending up to 5\,TeV are reached for $8<\left|Y^\ast\right|<10$. These measurements use a sample of data recorded using the ATLAS detector in 2011, which corresponds to an integrated luminosity of $4.51\,\text{fb}^{-1}$. Jets are identified using the anti-$k_\text{t}$ algorithm with two different jet radius parameters, $R=0.4$ and $R=0.6$.

Source code: ATLAS_2014_I1326641.cc
  1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 // -*- C++ -*- #include "Rivet/Analysis.hh" #include "Rivet/Projections/FinalState.hh" #include "Rivet/Projections/FastJets.hh" #include "Rivet/Tools/BinnedHistogram.hh" namespace Rivet { class ATLAS_2014_I1326641 : public Analysis { public: /// @name Constructors etc. //@{ /// Constructor ATLAS_2014_I1326641() : Analysis("ATLAS_2014_I1326641") { setNeedsCrossSection(true); } //@} public: /// @name Analysis methods //@{ /// Book histograms and initialise projections before the run void init() { //std::cout << " HELLO ANALYSIS : init " << std::endl; const FinalState fs; FastJets fj04(fs, FastJets::ANTIKT, 0.4); fj04.useInvisibles(); declare(fj04, "AntiKT04"); FastJets fj06(fs, FastJets::ANTIKT, 0.6); fj06.useInvisibles(); declare(fj06, "AntiKT06"); double ystarBins[] = { 0.0, 2.0, 4.0, 6.0, 8.0, 10.0 }; size_t massDsOffset(0); for (size_t alg = 0; alg < 2; ++alg) { for (size_t i = 0; i < 5; ++i) { h_trijet_Mass[alg].addHistogram(ystarBins[i], ystarBins[i+1], bookHisto1D(1 + massDsOffset, 1, 1)); massDsOffset += 1; } } } /// Perform the per-event analysis void analyze(const Event& event) { Jets jetAr[2]; jetAr[AKT4] = apply(event, "AntiKT04").jetsByPt(Cuts::pT > 50*GeV); jetAr[AKT6] = apply(event, "AntiKT06").jetsByPt(Cuts::pT > 50*GeV); const size_t nJets = 3; double ptCut[nJets] = { 150., 100., 50.}; // Loop over jet "radii" used in analysis for (size_t alg = 0; alg < 2; ++alg) { // Identify 3jets vector leadJets; foreach (const Jet& jet, jetAr[alg]) { if (jet.absrap() < 3.0 && leadJets.size() < nJets){ int filledJets = leadJets.size(); if (jet.pT() < ptCut[filledJets]) continue; leadJets.push_back(jet.momentum()); } } if (leadJets.size() < nJets) { MSG_DEBUG("Could not find three suitable leading jets"); continue; } const double y1 = leadJets[0].rapidity(); const double y2 = leadJets[1].rapidity(); const double y3 = leadJets[2].rapidity(); const double yStar = fabs(y1-y2) + fabs(y2-y3) + fabs(y1-y3); const double m = (leadJets[0] + leadJets[1] + leadJets[2]).mass(); h_trijet_Mass[alg].fill(yStar, m, event.weight()); } } /// Normalise histograms etc., after the run void finalize() { const double sf( 2.0 * crossSection() / sumOfWeights() ); for (size_t alg = 0; alg < 2; ++alg) { h_trijet_Mass[alg].scale(sf, this); } } //@} private: // Data members like post-cuts event weight counters go here enum Alg { AKT4=0, AKT6=1 }; private: // The 3 jets mass spectrum for anti-kt 4 and anti-kt 6 jets (array index is jet type from enum above) BinnedHistogram h_trijet_Mass[2]; }; // The hook for the plugin system DECLARE_RIVET_PLUGIN(ATLAS_2014_I1326641); }