Rivet analyses referenceCMS_2021_I1866118Study of Z boson plus jets events using variables sensitive to double-parton scattering in pp collisions at 13 TeVExperiment: CMS (LHC) Inspire ID: 1866118 Status: VALIDATED Authors:
Beam energies: (6500.0, 6500.0) GeV Run details:
Double parton scattering is investigated using events with a Z boson and jets. The measurements are performed with proton-proton collision data recorded by the CMS experiment at the LHC at $\sqrt{s} = 13$ TeV, corresponding to an integrated luminosity of $35.8 \mathrm{fb}^{-1}$ collected in the year 2016. Differential cross sections of Z$+ \geq$ 1 jet and Z$+ \geq$ 2 jets are measured with transverse momentum of the jets above 20 GeV and pseudorapidity $|\eta| <$ 2.4. Several distributions with sensitivity to double parton scattering effects are measured as functions of the angle and the transverse momentum imbalance between the Z boson and the jets. The measured distributions are compared with predictions from several event generators with different hadronization models and different parameter settings for multiparton interactions. The measured distributions show a dependence on the hadronization and multiparton interaction simulation parameters, and are important input for future improvements of the simulations. Source code: CMS_2021_I1866118.cc 1// -*- C++ -*-
2#include "Rivet/Analysis.hh"
3#include "Rivet/Projections/FinalState.hh"
4#include "Rivet/Projections/DileptonFinder.hh"
5#include "Rivet/Projections/FinalState.hh"
6#include "Rivet/Projections/ChargedFinalState.hh"
7#include "Rivet/Projections/VetoedFinalState.hh"
8#include "Rivet/Projections/FastJets.hh"
9
10namespace Rivet {
11
12
13 /// Z boson + jets sensitive to double-parton scattering at 13 TeV
14 class CMS_2021_I1866118 : public Analysis {
15 public:
16
17 /// Constructor
18 RIVET_DEFAULT_ANALYSIS_CTOR(CMS_2021_I1866118);
19
20
21 /// Initialization
22 void init() {
23
24 Cut cut = Cuts::abseta < 2.4 && Cuts::pT > 27 * GeV;
25 DileptonFinder zmumufinder(91.2*GeV, 0.1, cut && Cuts::abspid == PID::MUON, Cuts::massIn(70*GeV, 110*GeV));
26 declare(zmumufinder, "zmumufinder");
27
28 // Define veto FS in order to prevent Z-decay products entering the jet algorithm
29
30 VetoedFinalState had_fs;
31 had_fs.addVetoOnThisFinalState(zmumufinder);
32 FastJets jets(had_fs, JetAlg::ANTIKT, 0.4);
33 jets.useInvisibles();
34 declare(jets, "jets");
35
36 book(h_dphi_Z1J_cn, 1, 1, 1);
37 book(h_reldpt_Z1J_cn, 2, 1, 1);
38 book(h_dphi_Zdijet_Z2J_cn, 3, 1, 1);
39 book(h_reldpt_Zdijet_Z2J_cn, 4, 1, 1);
40 book(h_reldpt_j1j2_Z2J_cn, 5, 1, 1);
41
42 book(_h["dphi_Z1J"], 6, 1, 1);
43 book(_h["reldpt_Z1J"], 7, 1, 1);
44 book(_h["dphi_Zdijet_Z2J"], 8, 1, 1);
45 book(_h["reldpt_Zdijet_Z2J"], 9, 1, 1);
46 book(_h["reldpt_j1j2_Z2J"], 10, 1, 1);
47 }
48
49
50 /// Perform the per-event analysis
51 void analyze(const Event& event) {
52 const DileptonFinder& zmumufinder = apply<DileptonFinder>(event, "zmumufinder");
53 const Particles& zmumus = zmumufinder.bosons();
54 if (zmumus.size() != 1) {
55 vetoEvent;
56 }
57
58 // Find the (dressed!) leptons
59 const Particles& leptons = zmumufinder.constituents();
60 if (leptons.size() != 2)
61 vetoEvent;
62
63 Jets jets = apply<FastJets>(event, "jets").jetsByPt(Cuts::pT > 20 * GeV && Cuts::abseta < 2.4);
64 idiscardIfAnyDeltaRLess(jets, leptons, 0.4);
65
66 const size_t Njets = jets.size();
67
68 if (Njets < 1)
69 vetoEvent;
70
71 if (Njets >= 1) {
72 h_dphi_Z1J_cn->fill(deltaPhi(zmumus[0], jets[0]));
73 h_reldpt_Z1J_cn->fill((zmumus[0] + jets[0].momentum()).pt() / (zmumus[0].pt() + jets[0].pt()));
74
75 _h["dphi_Z1J"]->fill(deltaPhi(zmumus[0], jets[0]));
76 _h["reldpt_Z1J"]->fill((zmumus[0] + jets[0].momentum()).pt() / (zmumus[0].pt() + jets[0].pt()));
77 }
78
79 if (Njets >= 2) {
80 FourMomentum dij = jets[0].momentum() + jets[1].momentum();
81
82 h_dphi_Zdijet_Z2J_cn->fill(deltaPhi(zmumus[0], dij));
83 h_reldpt_Zdijet_Z2J_cn->fill((zmumus[0] + dij).pt() / (zmumus[0].pt() + dij.pt()));
84 h_reldpt_j1j2_Z2J_cn->fill(dij.pt() / (jets[0].pt() + jets[1].pt()));
85
86 _h["dphi_Zdijet_Z2J"]->fill(deltaPhi(zmumus[0], dij));
87 _h["reldpt_Zdijet_Z2J"]->fill((zmumus[0] + dij).pt() / (zmumus[0].pt() + dij.pt()));
88 _h["reldpt_j1j2_Z2J"]->fill(dij.pt() / (jets[0].pt() + jets[1].pt()));
89 }
90 }
91
92
93 /// Normalise histograms etc., after the run
94 void finalize() {
95 double norm = (sumOfWeights() != 0) ? crossSection()/picobarn/sumOfWeights() : 1.0;
96
97 scale(h_dphi_Z1J_cn, norm);
98 scale(h_reldpt_Z1J_cn, norm);
99 scale(h_dphi_Zdijet_Z2J_cn, norm);
100 scale(h_reldpt_Zdijet_Z2J_cn, norm);
101 scale(h_reldpt_j1j2_Z2J_cn, norm);
102
103 for (auto& item : _h) {
104 double rho = item.second->densitySum(false);
105 if (rho) scale(item.second, 1.0/rho);
106 }
107 }
108
109
110 private:
111
112 /// @name Histogram objects
113 /// @{
114 Histo1DPtr h_dphi_Z1J_cn;
115 Histo1DPtr h_reldpt_Z1J_cn;
116 Histo1DPtr h_dphi_Zdijet_Z2J_cn;
117 Histo1DPtr h_reldpt_Zdijet_Z2J_cn;
118 Histo1DPtr h_reldpt_j1j2_Z2J_cn;
119 map<string,Histo1DPtr> _h;
120 /// @}
121
122 };
123
124
125 RIVET_DECLARE_PLUGIN(CMS_2021_I1866118);
126
127}
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