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Rivet analyses reference
CMS_2021_I1866118
Study of Z boson plus jets events using variables sensitive to double-parton scattering in pp collisions at 13 TeV
Experiment: CMS (LHC)
Inspire ID: 1866118
Status: VALIDATED
Authors:
- cms-pag-conveners-smp@cern.ch
- Rajat Gupta
- Meena
- Sunil Bansal
- J.B. Singh
References:
Beams: p+ p+
Beam energies: (6500.0, 6500.0) GeV
Run details:
- Drell-Yan events with $Z/\gamma^* \to \mu\mu$.
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
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135 | // -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/FinalState.hh"
#include "Rivet/Projections/ZFinder.hh"
#include "Rivet/Projections/FinalState.hh"
#include "Rivet/Projections/ChargedFinalState.hh"
#include "Rivet/Projections/VetoedFinalState.hh"
#include "Rivet/Projections/FastJets.hh"
namespace Rivet {
/// @brief Study of Z boson plus jets events using variables sensitive to double-parton scattering in pp collisions at 13 TeV
class CMS_2021_I1866118 : public Analysis {
public:
/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(CMS_2021_I1866118);
/// Initialization
void init() {
const FinalState fs;
Cut cut = Cuts::abseta < 2.4 && Cuts::pT > 27 * GeV;
ZFinder zmumufinder(fs, cut, PID::MUON, 70 * GeV, 110 * GeV);
declare(zmumufinder, "zmumufinder");
// Define veto FS in order to prevent Z-decay products entering the jet algorithm
VetoedFinalState had_fs;
had_fs.addVetoOnThisFinalState(zmumufinder);
FastJets jets(had_fs, FastJets::ANTIKT, 0.4);
jets.useInvisibles();
declare(jets, "jets");
book(h_dphi_Z1J_cn, 1, 1, 1);
book(h_reldpt_Z1J_cn, 2, 1, 1);
book(h_dphi_Zdijet_Z2J_cn, 3, 1, 1);
book(h_reldpt_Zdijet_Z2J_cn, 4, 1, 1);
book(h_reldpt_j1j2_Z2J_cn, 5, 1, 1);
book(h_dphi_Z1J_sc, 6, 1, 1);
book(h_reldpt_Z1J_sc, 7, 1, 1);
book(h_dphi_Zdijet_Z2J_sc, 8, 1, 1);
book(h_reldpt_Zdijet_Z2J_sc, 9, 1, 1);
book(h_reldpt_j1j2_Z2J_sc, 10, 1, 1);
}
/// Perform the per-event analysis
void analyze(const Event& event) {
const ZFinder& zmumufinder = apply<ZFinder>(event, "zmumufinder");
const Particles& zmumus = zmumufinder.bosons();
if (zmumus.size() != 1) {
vetoEvent;
}
// Find the (dressed!) leptons
const Particles& leptons = zmumufinder.constituents();
if (leptons.size() != 2)
vetoEvent;
Jets jets = apply<FastJets>(event, "jets").jetsByPt(Cuts::pT > 20 * GeV && Cuts::abseta < 2.4);
idiscardIfAnyDeltaRLess(jets, leptons, 0.4);
const size_t Njets = jets.size();
if (Njets < 1)
vetoEvent;
if (Njets >= 1) {
h_dphi_Z1J_cn->fill(deltaPhi(zmumus[0], jets[0]));
h_reldpt_Z1J_cn->fill((zmumus[0] + jets[0].momentum()).pt() / (zmumus[0].pt() + jets[0].pt()));
h_dphi_Z1J_sc->fill(deltaPhi(zmumus[0], jets[0]));
h_reldpt_Z1J_sc->fill((zmumus[0] + jets[0].momentum()).pt() / (zmumus[0].pt() + jets[0].pt()));
}
if (Njets >= 2) {
FourMomentum dij = jets[0].momentum() + jets[1].momentum();
h_dphi_Zdijet_Z2J_cn->fill(deltaPhi(zmumus[0], dij));
h_reldpt_Zdijet_Z2J_cn->fill((zmumus[0] + dij).pt() / (zmumus[0].pt() + dij.pt()));
h_reldpt_j1j2_Z2J_cn->fill(dij.pt() / (jets[0].pt() + jets[1].pt()));
h_dphi_Zdijet_Z2J_sc->fill(deltaPhi(zmumus[0], dij));
h_reldpt_Zdijet_Z2J_sc->fill((zmumus[0] + dij).pt() / (zmumus[0].pt() + dij.pt()));
h_reldpt_j1j2_Z2J_sc->fill(dij.pt() / (jets[0].pt() + jets[1].pt()));
}
}
void normalizeToSum(Histo1DPtr hist) {
double sum = 0.;
for (size_t i = 0; i < hist->numBins(); ++i) {
sum += hist->bin(i).height();
}
scale(hist, 1. / sum);
}
/// Normalise histograms etc., after the run
void finalize() {
double norm = (sumOfWeights() != 0) ? crossSection()/picobarn/sumOfWeights() : 1.0;
scale(h_dphi_Z1J_cn, norm);
scale(h_reldpt_Z1J_cn, norm);
scale(h_dphi_Zdijet_Z2J_cn, norm);
scale(h_reldpt_Zdijet_Z2J_cn, norm);
scale(h_reldpt_j1j2_Z2J_cn, norm);
normalizeToSum(h_dphi_Z1J_sc);
normalizeToSum(h_reldpt_Z1J_sc);
normalizeToSum(h_dphi_Zdijet_Z2J_sc);
normalizeToSum(h_reldpt_Zdijet_Z2J_sc);
normalizeToSum(h_reldpt_j1j2_Z2J_sc);
}
private:
/// @name Histogram objects
//@{
Histo1DPtr h_dphi_Z1J_cn;
Histo1DPtr h_reldpt_Z1J_cn;
Histo1DPtr h_dphi_Zdijet_Z2J_cn;
Histo1DPtr h_reldpt_Zdijet_Z2J_cn;
Histo1DPtr h_reldpt_j1j2_Z2J_cn;
Histo1DPtr h_dphi_Z1J_sc;
Histo1DPtr h_reldpt_Z1J_sc;
Histo1DPtr h_dphi_Zdijet_Z2J_sc;
Histo1DPtr h_reldpt_Zdijet_Z2J_sc;
Histo1DPtr h_reldpt_j1j2_Z2J_sc;
//@}
};
// Hook for the plugin system
RIVET_DECLARE_PLUGIN(CMS_2021_I1866118);
} // namespace Rivet
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