Rivet analyses referenceCMS_2016_I1486238Studies of 2 $b$-jet + 2 jet production in proton-proton collisions at 7 TeVExperiment: CMS (LHC) Inspire ID: 1486238 Status: VALIDATED Authors:
Beam energies: (3500.0, 3500.0) GeV Run details:
Measurements are presented of the cross section for the production of at least four jets, of which at least two originate from $b$ quarks, in proton-proton collisions. Data collected with the CMS detector at the LHC at a center-of-mass energy of 7 TeV are used, corresponding to an integrated luminosity of 3 inverse picobarns. The cross section is measured as a function of the jet transverse momentum for p_\perp 20 GeV, and of the jet pseudorapidity for $|\eta|<2.4$ ($b$ jets) and 4.7 (untagged jets). The correlations in azimuthal angle and p_\perp between the jets are also studied. The $\eta$ and p_\perp distributions of the four jets and the correlations between them are well reproduced by event generators that combine perturbative QCD calculations at next-to-leading-order accuracy with contributions from parton showers and multiparton interactions. Source code: CMS_2016_I1486238.cc 1// -*- C++ -*-
2#include "Rivet/Analysis.hh"
3#include "Rivet/Projections/FinalState.hh"
4#include "Rivet/Projections/FastJets.hh"
5
6#define I_KNOW_THE_INITIAL_QUARKS_PROJECTION_IS_DODGY_BUT_NEED_TO_USE_IT
7#include "Rivet/Projections/InitialQuarks.hh"
8
9namespace Rivet {
10
11
12 /// Studies of 2 b-jet + 2 jet production in proton-proton collisions at 7 TeV
13 class CMS_2016_I1486238 : public Analysis {
14 public:
15
16 /// Constructor
17 RIVET_DEFAULT_ANALYSIS_CTOR(CMS_2016_I1486238);
18
19
20 /// @name Analysis methods
21 //@{
22
23 /// Book histograms and initialise projections before the run
24 void init() {
25
26 FastJets akt(FinalState(), FastJets::ANTIKT, 0.5);
27 declare(akt, "antikT");
28
29 book(_h_Deltaphi_newway, 1,1,1);
30 book(_h_deltaphiafterlight, 9,1,1);
31 book(_h_SumPLight, 5,1,1);
32
33 book(_h_LeadingBJetpt, 11,1,1);
34 book(_h_SubleadingBJetpt, 15,1,1);
35 book(_h_LeadingLightJetpt, 13,1,1);
36 book(_h_SubleadingLightJetpt, 17,1,1);
37
38 book(_h_LeadingBJeteta, 10,1,1);
39 book(_h_SubleadingBJeteta, 14,1,1);
40 book(_h_LeadingLightJeteta, 12,1,1);
41 book(_h_SubleadingLightJeteta, 16,1,1);
42 }
43
44
45 /// Perform the per-event analysis
46 void analyze(const Event& event) {
47 const Jets& jets = apply<JetAlg>(event, "antikT").jetsByPt(Cuts::absrap < 4.7 && Cuts::pT > 20*GeV);
48 if (jets.size() < 4) vetoEvent;
49
50 // Initial quarks
51 /// @note Quark-level tagging...
52 Particles bquarks;
53 for (ConstGenParticlePtr p : HepMCUtils::particles(event.genEvent())) {
54 if (abs(p->pdg_id()) == PID::BQUARK) bquarks += Particle(p);
55 }
56 Jets bjets, ljets;
57 for (const Jet& j : jets) {
58 const bool btag = any(bquarks, deltaRLess(j, 0.3));
59 // for (const Particle& b : bquarks) if (deltaR(j, b) < 0.3) btag = true;
60 (btag && j.abseta() < 2.4 ? bjets : ljets).push_back(j);
61 }
62
63 // Fill histograms
64 const double weight = 1.0;
65 if (bjets.size() >= 2 && ljets.size() >= 2) {
66 _h_LeadingBJetpt->fill(bjets[0].pT()/GeV, weight);
67 _h_SubleadingBJetpt->fill(bjets[1].pT()/GeV, weight);
68 _h_LeadingLightJetpt->fill(ljets[0].pT()/GeV, weight);
69 _h_SubleadingLightJetpt->fill(ljets[1].pT()/GeV, weight);
70 //
71 _h_LeadingBJeteta->fill(bjets[0].eta(), weight);
72 _h_SubleadingBJeteta->fill(bjets[1].eta(), weight);
73 _h_LeadingLightJeteta->fill(ljets[0].eta(), weight);
74 _h_SubleadingLightJeteta->fill(ljets[1].eta(), weight);
75
76 const double lightdphi = deltaPhi(ljets[0], ljets[1]);
77 _h_deltaphiafterlight->fill(lightdphi, weight);
78
79 const double vecsumlightjets = sqrt(sqr(ljets[0].px()+ljets[1].px()) + sqr(ljets[0].py()+ljets[1].py())); //< @todo Just (lj0+lj1).pT()? Or use add_quad
80 const double term2 = vecsumlightjets/(sqrt(sqr(ljets[0].px()) + sqr(ljets[0].py())) + sqrt(sqr(ljets[1].px()) + sqr(ljets[1].py()))); //< @todo lj0.pT() + lj1.pT()? Or add_quad
81 _h_SumPLight->fill(term2, weight);
82
83 const double pxBsyst2 = bjets[0].px()+bjets[1].px(); // @todo (bj0+bj1).px()
84 const double pyBsyst2 = bjets[0].py()+bjets[1].py(); // @todo (bj0+bj1).py()
85 const double pxJetssyst2 = ljets[0].px()+ljets[1].px(); // @todo (lj0+lj1).px()
86 const double pyJetssyst2 = ljets[0].py()+ljets[1].py(); // @todo (lj0+lj1).py()
87 const double modulusB2 = sqrt(sqr(pxBsyst2)+sqr(pyBsyst2)); //< @todo add_quad
88 const double modulusJets2 = sqrt(sqr(pxJetssyst2)+sqr(pyJetssyst2)); //< @todo add_quad
89 const double cosphiBsyst2 = pxBsyst2/modulusB2;
90 const double cosphiJetssyst2 = pxJetssyst2/modulusJets2;
91 const double phiBsyst2 = ((pyBsyst2 > 0) ? 1 : -1) * acos(cosphiBsyst2); //< @todo sign(pyBsyst2)
92 const double phiJetssyst2 = sign(pyJetssyst2) * acos(cosphiJetssyst2);
93 const double Dphi2 = deltaPhi(phiBsyst2, phiJetssyst2);
94 _h_Deltaphi_newway->fill(Dphi2,weight);
95 }
96 }
97
98
99 /// Normalise histograms etc., after the run
100 void finalize() {
101 const double invlumi = crossSection()/picobarn/sumOfWeights();
102 normalize(_h_SumPLight); normalize(_h_deltaphiafterlight); normalize(_h_Deltaphi_newway);
103 scale(_h_LeadingLightJetpt, invlumi); scale(_h_SubleadingLightJetpt, invlumi);
104 scale(_h_LeadingBJetpt, invlumi); scale(_h_SubleadingBJetpt, invlumi);
105 scale(_h_LeadingLightJeteta, invlumi); scale(_h_SubleadingLightJeteta, invlumi);
106 scale(_h_LeadingBJeteta, invlumi); scale(_h_SubleadingBJeteta, invlumi);
107 }
108
109 //@}
110
111
112 private:
113
114 /// @name Histograms
115 //@{
116
117 Histo1DPtr _h_deltaphiafterlight, _h_Deltaphi_newway, _h_SumPLight;
118 Histo1DPtr _h_LeadingBJetpt, _h_SubleadingBJetpt, _h_LeadingLightJetpt, _h_SubleadingLightJetpt;
119 Histo1DPtr _h_LeadingBJeteta, _h_SubleadingBJeteta, _h_LeadingLightJeteta, _h_SubleadingLightJeteta;
120
121 };
122
123
124 // Hook for the plugin system
125 RIVET_DECLARE_PLUGIN(CMS_2016_I1486238);
126
127}
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