Rivet analyses

title: ATLAS_2010_CONF_2010_049

Cross-section and fragmentation function in anti-$k_t$ track jets

Experiment: ATLAS (LHC 7000GeV)

Inspire ID: 1204039

Status: OBSOLETE

Authors: - Hendrik Hoeth

References: - Expt page: ATLAS-CONF-2010-049

Beams: p+ p+

Beam energies: (3500.0, 3500.0)GeV

Run details: - pp QCD interactions at 7000 GeV including diffractive events.

Jets are identified and their properties studied using tracks measured by the ATLAS Inner Detector. Events are selected using a minimum-bias trigger, allowing the emergence of jets at low transverse momentum to be observed and for jets to be studied independently of the calorimeter. Jets are reconstructed using the anti-kt algorithm applied to tracks with two parameter choices, 0.4 and 0.6. An inclusive jet transverse momentum cross section measurement from 4 GeV to 80 GeV is shown, integrated over $|\eta| < 0.57$ and corrected to charged particle-level truth jets. The probability that a particular particle carries a fixed fraction of the jet momentum (fragmentation function) is also measured. All data is corrected to the particle level. ATTENTION - Data read from plots!

Source code:ATLAS_2010_CONF_2010_049.cc

```c++ // -- C++ --

include "Rivet/Analysis.hh"

include "Rivet/Projections/ChargedFinalState.hh"

include "Rivet/Projections/FastJets.hh"

namespace Rivet {

class ATLAS_2010_CONF_2010_049 : public Analysis { public:

ATLAS_2010_CONF_2010_049()
    : Analysis("ATLAS_2010_CONF_2010_049") { }


void init() {
  ChargedFinalState cfs((Cuts::etaIn(-1.5, 1.5) && Cuts::pT >= 0.5 * GeV));
  declare(cfs, "CFS");

  FastJets jetsproj6(cfs, JetAlg::ANTIKT, 0.6);
  declare(jetsproj6, "Jets6");

  FastJets jetsproj4(cfs, JetAlg::ANTIKT, 0.4);
  declare(jetsproj4, "Jets4");

  /// @todo tmp YOs
  for (size_t i = 0; i < 2; i++) {
    book(_h_xsec[i], 1 + i, 1, 1);
    book(_h_frag_04_06[i], 3 + i, 1, 1);
    book(_h_frag_06_10[i], 3 + i, 2, 1);
    book(_h_frag_10_15[i], 3 + i, 3, 1);
    book(_h_frag_15_24[i], 3 + i, 4, 1);
    book(_njets_04_06[i], "njets_04_06_" + to_string(i));
    book(_njets_06_10[i], "njets_06_10_" + to_string(i));
    book(_njets_10_15[i], "njets_10_15_" + to_string(i));
    book(_njets_15_24[i], "njets_15_24_" + to_string(i));
  }
}


void analyze(const Event& event) {
  const FastJets& jetsproj6 = apply<FastJets>(event, "Jets6");
  const FastJets& jetsproj4 = apply<FastJets>(event, "Jets4");
  Jets alljets[2];
  alljets[0] = jetsproj6.jetsByPt(Cuts::pT > 4 * GeV);
  alljets[1] = jetsproj4.jetsByPt(Cuts::pT > 4 * GeV);

  for (size_t i = 0; i < 2; i++) {
    Jets jets;

    // First we want to make sure that we only use jets within |eta|<0.57
    for (const Jet& jet : alljets[i]) {
      if (jet.abseta() < 0.57) {
        jets.push_back(jet);
      }
    }
    for (const Jet& jet : jets) {
      const double pTjet = jet.pT();
      const double pjet = jet.p3().mod();
      _h_xsec[i]->fill(pTjet);
      if (pTjet > 24 * GeV) continue;
      for (const Particle& p : jet.particles()) {
        double z = p.p3().mod() / pjet;
        if (z >= 1) z = 0.9999; // Make sure that z=1 doesn't go into overflow
        if (pTjet > 15 * GeV) {
          _h_frag_15_24[i]->fill(z);
        }
        else if (pTjet > 10 * GeV) {
          _h_frag_10_15[i]->fill(z);
        }
        else if (pTjet > 6 * GeV) {
          _h_frag_06_10[i]->fill(z);
        }
        else {
          _h_frag_04_06[i]->fill(z);
        }
      }
      if (pTjet > 15 * GeV) {
        _njets_15_24[i]->fill();
      }
      else if (pTjet > 10 * GeV) {
        _njets_10_15[i]->fill();
      }
      else if (pTjet > 6 * GeV) {
        _njets_06_10[i]->fill();
      }
      else {
        _njets_04_06[i]->fill();
      }
    }
  }
}

void finalize() {
  for (size_t i = 0; i < 2; i++) {
    // deta = 2*0.57
    scale(_h_xsec[i], crossSection() / microbarn / sumOfWeights() / (2 * 0.57));
    scale(_h_frag_04_06[i], 1. / _njets_04_06[i]->val());
    scale(_h_frag_06_10[i], 1. / _njets_06_10[i]->val());
    scale(_h_frag_10_15[i], 1. / _njets_10_15[i]->val());
    scale(_h_frag_15_24[i], 1. / _njets_15_24[i]->val());
  }
}

private:

Histo1DPtr _h_xsec[2];
Histo1DPtr _h_frag_04_06[2];
Histo1DPtr _h_frag_06_10[2];
Histo1DPtr _h_frag_10_15[2];
Histo1DPtr _h_frag_15_24[2];
CounterPtr _njets_04_06[2];
CounterPtr _njets_06_10[2];
CounterPtr _njets_10_15[2];
CounterPtr _njets_15_24[2];

};

RIVET_DECLARE_PLUGIN(ATLAS_2010_CONF_2010_049);

} ```