Rivet analyses
title: CMS_2013_I1261026
Jet and underlying event properties as a function of particle multiplicity
Experiment: CMS (LHC)
Inspire ID: 1261026
Status: VALIDATED
Authors: - Maxim Azarkin
References: - Eur.Phys.J. C73 (2013) 2674 - arXiv: 1310.4554 - Expt page: CMS-FSQ-12-022, - CERN-PH-EP-2013-195
Beams: p+ p+
Beam energies: (3500.0, 3500.0)GeV
Run details: - QCD MB
Characteristics of multi-particle production in proton-proton collisions at $\sqrt{s} = 7$ TeV are studied as a function of the charged-particle multiplicity ($N_\text{ch}$). The produced particles are separated into two classes: those belonging to jets and those belonging to the underlying event. Charged particles are measured with pseudorapidity $|\eta| < 2.4$ and transverse momentum $p_\text{T} > 0.25$ GeV. Jets are reconstructed from charged-particles only and required to have $p_\text{T} > 5$ GeV. The distributions of jet $p_\text{T}$, average $p_\text{T}$ of charged particles belonging to the underlying event or to jets, jet rates, and jet shapes are presented as functions of $N_\text{ch}$.
Source code:CMS_2013_I1261026.cc
```c++ // -- C++ --
include "Rivet/Analysis.hh"
include "Rivet/Projections/Beam.hh"
include "Rivet/Projections/ChargedFinalState.hh"
include "Rivet/Projections/FastJets.hh"
include "Rivet/Projections/FinalState.hh"
include "Rivet/Projections/VetoedFinalState.hh"
namespace Rivet {
/// Jet and underlying event properties as a function of particle multiplicity class CMS_2013_I1261026 : public Analysis { public:
RIVET_DEFAULT_ANALYSIS_CTOR(CMS_2013_I1261026);
void init() {
const ChargedFinalState cfs(Cuts::abseta < 2.4 && Cuts::pT > 0.25 * GeV);
declare(cfs, "CFS250");
FastJets jetpro(cfs, JetAlg::ANTIKT, 0.5);
declare(jetpro, "Jets");
// For min bias trigger
const ChargedFinalState cfsBSCplus(Cuts::etaIn(3.23, 4.65) && Cuts::pT > 500 * MeV);
declare(cfsBSCplus, "cfsBSCplus");
const ChargedFinalState cfsBSCminus(Cuts::etaIn(-4.65, -3.23) && Cuts::pT > 500 * MeV);
declare(cfsBSCminus, "cfsBSCminus");
// Histograms:
book(_h_AllTrkMeanPt, 1, 1, 1);
book(_h_SoftTrkMeanPt, 2, 1, 1);
book(_h_IntrajetTrkMeanPt, 3, 1, 1);
book(_h_IntrajetLeaderTrkMeanPt, 4, 1, 1);
book(_h_MeanJetPt, 5, 1, 1);
book(_h_JetRate5GeV, 6, 1, 1);
book(_h_JetRate30GeV, 7, 1, 1);
for (int ihist = 0; ihist < 5; ++ihist) {
book(_h_JetSpectrum[ihist], ihist + 8, 1, 1);
book(_h_JetStruct[ihist], ihist + 13, 1, 1);
}
}
/// Perform the per-event analysis
void analyze(const Event& event) {
// MinBias trigger
const ChargedFinalState& cfsBSCplus = apply<ChargedFinalState>(event, "cfsBSCplus");
if (cfsBSCplus.empty()) vetoEvent;
const ChargedFinalState& cfsBSCminus = apply<ChargedFinalState>(event, "cfsBSCminus");
if (cfsBSCminus.empty()) vetoEvent;
const ChargedFinalState& cfsp = apply<ChargedFinalState>(event, "CFS250");
if (cfsp.empty()) vetoEvent;
const FastJets& jetpro = apply<FastJets>(event, "Jets");
const Jets& jets = jetpro.jetsByPt(Cuts::pT > 5 * GeV);
const int mult = cfsp.size();
int multbin[6] = {10, 30, 50, 80, 110, 140};
for (int ibin = 0; ibin < 5; ++ibin) {
if (mult > multbin[ibin] && mult <= multbin[ibin + 1]) {
eventDecomp(event, mult, ibin);
unsigned int jetCounter5GeV(0), jetCounter30GeV(0);
for (size_t ijets = 0; ijets < jets.size(); ++ijets) {
if (jets[ijets].abseta() < 1.9) {
_h_JetSpectrum[ibin]->fill(jets[ijets].pT() / GeV);
_h_MeanJetPt->fill(mult, jets[ijets].pT() / GeV);
if (jets[ijets].pT() > 5 * GeV) ++jetCounter5GeV;
if (jets[ijets].pT() > 30 * GeV) ++jetCounter30GeV;
}
}
_h_JetRate5GeV->fill(mult, jetCounter5GeV);
_h_JetRate30GeV->fill(mult, jetCounter30GeV);
}
}
}
/// Normalise histograms etc., after the run
void finalize() {
for (size_t i = 0; i < 5; ++i) {
normalize(_h_JetSpectrum[i], 4.0);
normalize(_h_JetStruct[i], 0.08);
}
}
void eventDecomp(const Event& event, int mult, size_t ibin) {
struct TrkInJet {
double pt;
double eta;
double phi;
double R;
};
TrkInJet jetConstituents[100][100]; //1-st index - the number of the jet, 2-nd index - track in the jet
TrkInJet jetsEv[100];
size_t j[100];
size_t jCount = 0;
for (size_t i = 0; i < 100; ++i) {
j[i] = 0;
jetsEv[i].pt = 0;
jetsEv[i].eta = 0;
jetsEv[i].phi = 0;
for (size_t k = 0; k < 100; ++k) {
jetConstituents[i][k].pt = 0;
jetConstituents[i][k].phi = 0;
jetConstituents[i][k].eta = 0;
jetConstituents[i][k].R = 0;
}
}
const FastJets& jetpro = apply<FastJets>(event, "Jets");
const Jets& jets = jetpro.jetsByPt(Cuts::pT > 5 * GeV);
// Start event decomp
for (size_t ijets = 0; ijets < jets.size(); ++ijets) {
jetsEv[ijets].pt = jets[ijets].pT();
jetsEv[ijets].eta = jets[ijets].eta();
jetsEv[ijets].phi = jets[ijets].phi();
jCount += 1;
}
const ChargedFinalState& cfsp = apply<ChargedFinalState>(event, "CFS250");
for (const Particle& p : cfsp.particles()) {
_h_AllTrkMeanPt->fill(mult, p.pT() / GeV);
int flag = 0;
for (size_t i = 0; i < jCount; ++i) {
const double delta_phi = deltaPhi(jetsEv[i].phi, p.phi());
const double delta_eta = jetsEv[i].eta - p.eta();
const double R = sqrt(delta_phi * delta_phi + delta_eta * delta_eta);
if (R <= 0.5) {
flag++;
jetConstituents[i][j[i]].pt = p.pT();
jetConstituents[i][j[i]].R = R;
j[i]++;
}
}
if (flag == 0) _h_SoftTrkMeanPt->fill(mult, p.pT() / GeV);
}
for (size_t i = 0; i < jCount; ++i) {
double ptInjetLeader = 0;
if (!inRange(jetsEv[i].eta, -1.9, 1.9))
continue; // only fully reconstructed jets for internal jet studies
for (size_t k = 0; k < j[i]; ++k) {
_h_IntrajetTrkMeanPt->fill(mult, jetConstituents[i][k].pt);
_h_JetStruct[ibin]->fill(jetConstituents[i][k].R, jetConstituents[i][k].pt / jetsEv[i].pt);
if (ptInjetLeader < jetConstituents[i][k].pt) ptInjetLeader = jetConstituents[i][k].pt;
}
if (ptInjetLeader != 0) _h_IntrajetLeaderTrkMeanPt->fill(mult, ptInjetLeader);
}
}
private:
Profile1DPtr _h_AllTrkMeanPt, _h_SoftTrkMeanPt;
Profile1DPtr _h_IntrajetTrkMeanPt, _h_IntrajetLeaderTrkMeanPt;
Profile1DPtr _h_MeanJetPt;
Profile1DPtr _h_JetRate5GeV, _h_JetRate30GeV;
array<Histo1DPtr, 5> _h_JetSpectrum;
array<Histo1DPtr, 5> _h_JetStruct;
};
RIVET_DECLARE_PLUGIN(CMS_2013_I1261026);
} ```