Rivet analyses

Measurements of jet charge with dijet events in pp collisions at $\sqrt{s}=8$ TeV

Experiment: CMS (LHC)

Inspire ID: 1605749

Status: VALIDATED

Authors: - Debarati Roy - Andreas Hinzmann - Nhan Viet Tran - Sunanda Banerjee

References: - DOI:10.1007/JHEP10(2017)131 - arXiv: 1706.05868 - Expt page: CMS-SMP-15-003

Beams: p+ p+

Beam energies: (4000.0, 4000.0)GeV

Run details: - pp QCD interactions at $\sqrt{s} = 8$ TeV. Data collected by CMS during the year 2012.

Jet charge is an estimator of the electric charge of a quark, antiquark, or gluon initiating a jet. It is based on the momentum-weighted sum of the electric charges of the jet constituents. Measurements of three charge observables of the leading jet in transverse momentum pT are performed with dijet events. The analysis is carried out with data collected by the CMS experiment at the CERN LHC in proton-proton collisions at $\sqrt{s}=8\TeV$ corresponding to an integrated luminosity of 19.7 fb−1. The results are presented in bins of the pT of the leading jet.

Source code:CMS_2017_I1605749.cc

// -*- C++ -*-
// Rivet framework
#include "Rivet/Analysis.hh"

// Projections
#include "Rivet/Projections/FinalState.hh"
#include "Rivet/Projections/FastJets.hh"

namespace Rivet {

  using namespace Cuts;

  class CMS_2017_I1605749 : public Analysis {
  public:

    // Constructor
    CMS_2017_I1605749()
      : Analysis("CMS_2017_I1605749")
    {    }

    // Book histograms and initialise projections before the run
    void init() {
      // Projections
      const FinalState fs((Cuts::etaIn(-5.0, 5.0)));
      declare(FastJets(fs, JetAlg::ANTIKT, 0.5), "Jets");

      // Jet Charge Histos
      for (int i = 1; i <= 18; i++) {
        book(_h_Charge[i - 1], i, 1, 1);
      }
    }

    // Perform the per-event analysis
    void analyze(const Event& event) {
      const Jets& jets = apply<FastJets>(event, "Jets").jetsByPt(Cuts::pT > 10.0*GeV);

      if (jets.size() < 2) vetoEvent;

      double leadingpt = jets[0].pt()/GeV;
      double subleadingpt = jets[1].pt()/GeV;

      if (jets.size() < 2 ||
          jets[0].abseta() >= 1.5 ||
          jets[1].abseta() >= 1.5 ||
          leadingpt < 400.0 || subleadingpt < 100.0) {
        vetoEvent;
      }

      vector<Particle> constituents1 = jets[0].constituents();
      std::vector<double> numerator(9, 0), denominator(9, 0);

      double t_jetcharge1, t_jetcharge1k6, t_jetcharge1k3;
      double t_jetchargeL1, t_jetchargeL1k6, t_jetchargeL1k3;
      double t_jetchargeT1, t_jetchargeT1k6, t_jetchargeT1k3;

      denominator[0] = leadingpt;
      denominator[1] = std::pow(leadingpt, 0.6);
      denominator[2] = std::pow(leadingpt, 0.3);

      if (constituents1.size() > 0) {
        for (unsigned j = 0; j < constituents1.size(); j++) {
          if (std::abs(constituents1[j].pid()) > 9 &&
              std::abs(constituents1[j].pid())!= 21) {
            if (constituents1[j].pt() > 1*GeV) {
              double charge = constituents1[j].charge();
              double mom = constituents1[j].pt();
              double dotproduct = constituents1[j].p3().dot(jets[0].p3()) / jets[0].p();
              double crossproduct = constituents1[j].p3().cross(jets[0].p3()).mod() / jets[0].p();

              numerator[0] += (mom * charge);
              numerator[1] += ((std::pow(mom, 0.6)) * charge);
              numerator[2] += ((std::pow(mom, 0.3)) * charge);

              numerator[3] += (dotproduct * charge);
              numerator[4] += ((std::pow(dotproduct, 0.6)) * charge);
              numerator[5] += ((std::pow(dotproduct, 0.3)) * charge);

              denominator[3] += dotproduct;
              denominator[4] += (std::pow(dotproduct, 0.6));
              denominator[5] += (std::pow(dotproduct, 0.3));

              numerator[6] += (crossproduct * charge);
              numerator[7] += ((std::pow(crossproduct, 0.6)) * charge);
              numerator[8] += ((std::pow(crossproduct, 0.3)) * charge);

              denominator[6] += crossproduct;
              denominator[7] += (std::pow(crossproduct, 0.6));
              denominator[8] += (std::pow(crossproduct, 0.3));
            }
          }
        }
      }

      t_jetcharge1    = (denominator[0] > 0) ? numerator[0] / denominator[0] : 0;
      t_jetcharge1k6  = (denominator[1] > 0) ? numerator[1] / denominator[1] : 0;
      t_jetcharge1k3  = (denominator[2] > 0) ? numerator[2] / denominator[2] : 0;
      t_jetchargeL1   = (denominator[3] > 0) ? numerator[3] / denominator[3] : 0;
      t_jetchargeL1k6 = (denominator[4] > 0) ? numerator[4] / denominator[4] : 0;
      t_jetchargeL1k3 = (denominator[5] > 0) ? numerator[5] / denominator[5] : 0;
      t_jetchargeT1   = (denominator[6] > 0) ? numerator[6] / denominator[6] : 0;
      t_jetchargeT1k6 = (denominator[7] > 0) ? numerator[7] / denominator[7] : 0;
      t_jetchargeT1k3 = (denominator[8] > 0) ? numerator[8] / denominator[8] : 0;

      _h_Charge[0]->fill(t_jetcharge1);
      _h_Charge[1]->fill(t_jetcharge1k6);
      _h_Charge[2]->fill(t_jetcharge1k3);
      _h_Charge[3]->fill(t_jetchargeL1);
      _h_Charge[4]->fill(t_jetchargeL1k6);
      _h_Charge[5]->fill(t_jetchargeL1k3);
      _h_Charge[6]->fill(t_jetchargeT1);
      _h_Charge[7]->fill(t_jetchargeT1k6);
      _h_Charge[8]->fill(t_jetchargeT1k3);

      if (leadingpt > 400 && leadingpt < 700) {
        _h_Charge[9]->fill(t_jetcharge1k6);
        _h_Charge[12]->fill(t_jetchargeL1k6);
        _h_Charge[15]->fill(t_jetchargeT1k6);
      } else if (leadingpt > 700 && leadingpt < 1000) {
        _h_Charge[10]->fill(t_jetcharge1k6);
        _h_Charge[13]->fill(t_jetchargeL1k6);
        _h_Charge[16]->fill(t_jetchargeT1k6);
      } else if (leadingpt > 1000 && leadingpt < 1800) {
        _h_Charge[11]->fill(t_jetcharge1k6);
        _h_Charge[14]->fill(t_jetchargeL1k6);
        _h_Charge[17]->fill(t_jetchargeT1k6);
      }
    }

    // Normalise histograms etc., after the run
    void finalize() {
      for (int j = 0; j < 18; ++j) {
        normalize(_h_Charge[j]);
      }
    }

  private:
    Histo1DPtr _h_Charge[18];
  };

  RIVET_DECLARE_PLUGIN(CMS_2017_I1605749);
}