Rivet analyses

title: CMS_2011_I916908

Traditional leading jet UE measurement at $\sqrt{s} = 0.9$ and 7 TeV

Experiment: CMS (LHC)

Inspire ID: 916908

Status: VALIDATED

Authors: - Mohammed Zakaria

References: - J. High Energy Phys 09 (2011) 109

Beams: p+ p+

Beam energies: (450.0, 450.0); (3500.0, 3500.0)GeV

Run details: - Requires inclusive inelastic events (non-diffractive and inelastic diffractive). The profile plots require large statistics.

A measurement of the underlying activity in scattering processes with a hard scale in the several-GeV region is performed in proton-proton collisions at Energies of 0.9 and 7~TeV, using data collected by the CMS experiment at the LHC. The production of charged particles with pseudorapidity $|\eta| < 2$ and transverse momentum $p_\text{T} > 0.5$~GeV/$c$ is studied in the azimuthal region transverse to that of the leading set of charged particles forming a track-jet. Various comparisons are made between the two different energies and also beteen two sets of cuts on $p_\text{T}$ for leading track jet $p_\text{T}$-leading $> 3$~GeV and $p_\text{T}$-leading $> 20$~GeV. The activity is studied using 5 types of plots. Two profile plots for the multiplicity of charged particles and the scalar sum of $p_\text{T}$, and three distributions for the two previous quantities as well as $p_\text{T}$ for all the particles in the transverse region.

Source code:CMS_2011_I916908.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/ChargedFinalState.hh"

include "Rivet/Projections/FastJets.hh"

include "Rivet/Projections/FinalState.hh"

namespace Rivet {

/// UE charged particles vs. leading jet class CMS_2011_I916908 : public Analysis { public:

RIVET_DEFAULT_ANALYSIS_CTOR(CMS_2011_I916908);


void init() {
  const ChargedFinalState cfs(Cuts::abseta < 2.0 && Cuts::pT >= 500 * MeV);
  declare(cfs, "CFS");

  const ChargedFinalState cfsforjet(Cuts::abseta < 2.5 && Cuts::pT >= 500 * MeV);
  const FastJets jetpro(cfsforjet, JetAlg::SISCONE, 0.5);
  declare(jetpro, "Jets");

  for (double eVal : allowedEnergies()) {
    const string en = toString(round(eVal));
    if (isCompatibleWithSqrtS(eVal)) _sqs = en;

    if (en == "7000"s) {
      book(_p[en + "Nch_vs_pT"], 1, 1, 1); // Nch vs. pT_max
      book(_p[en + "Sum_vs_pT"], 2, 1, 1); // sum(pT) vs. pT_max
      book(_h[en + "pT3_Nch"], 5, 1, 1);   // transverse Nch,     pT_max > 3GeV
      book(_h[en + "pT3_Sum"], 6, 1, 1);   // transverse sum(pT), pT_max > 3GeV
      book(_h[en + "pT3_pT"], 7, 1, 1);    // transverse pT,      pT_max > 3GeV
      book(_h[en + "pT20_Nch"], 8, 1, 1);  // transverse Nch,     pT_max > 20GeV
      book(_h[en + "pT20_Sum"], 9, 1, 1);  // transverse sum(pT), pT_max > 20GeV
      book(_h[en + "pT20_pT"], 10, 1, 1);  // transverse pT,      pT_max > 20GeV
    }
    else if (en == "900"s) {
      book(_p[en + "Nch_vs_pT"], 3, 1, 1); // Nch vs. pT_max
      book(_p[en + "Sum_vs_pT"], 4, 1, 1); // sum(pT) vs. pT_max
      book(_h[en + "pT3_Nch"], 11, 1, 1);  // transverse Nch,     pT_max > 3GeV
      book(_h[en + "pT3_Sum"], 12, 1, 1);  // transverse sum(pT), pT_max > 3GeV
      book(_h[en + "pT3_pT"], 13, 1, 1);   // transverse pT,      pT_max > 3GeV
    }
    book(_c[en + "pT3"], "TMP/nch_tot_pT3" + en);
    book(_c[en + "pT20"], "TMP/nch_tot_pT20" + en);
  }
  raiseBeamErrorIf(_sqs.empty());
}


/// Perform the per-event analysis
void analyze(const Event& event) {

  // Find the lead jet, applying a restriction that the jets must be within |eta| < 2.
  FourMomentum p_lead;
  for (const Jet& j :
       apply<FastJets>(event, "Jets").jetsByPt(Cuts::pT > 1.0 * GeV && Cuts::abseta < 2.0)) {
    p_lead = j.momentum();
    break;
  }
  if (p_lead.isZero()) vetoEvent;
  const double philead = p_lead.phi();
  const double pTlead = p_lead.pT();

  Particles particles = apply<ChargedFinalState>(event, "CFS").particlesByPt();

  int nTransverse = 0;
  double ptSumTransverse = 0.;
  for (const Particle& p : particles) {
    double dphi = deltaPhi(philead, p.phi());
    if (dphi > PI / 3. && dphi < PI * 2. / 3.) { // Transverse region
      ++nTransverse;

      const double pT = p.pT() / GeV;
      ptSumTransverse += pT;

      if (pTlead > 3 * GeV) _h[_sqs + "pT3_pT"]->fill(pT / GeV);
      if (_sqs == "7000"s && pTlead > 20 * GeV) _h[_sqs + "pT20_pT"]->fill(pT / GeV);
    }
  }

  const double area = 8. / 3. * PI;
  _p[_sqs + "Nch_vs_pT"]->fill(pTlead / GeV, 1. / area * nTransverse);
  _p[_sqs + "Sum_vs_pT"]->fill(pTlead / GeV, 1. / area * ptSumTransverse);
  if (pTlead > 3.0 * GeV) {
    _h[_sqs + "pT3_Nch"]->fill(nTransverse);
    _h[_sqs + "pT3_Sum"]->fill(ptSumTransverse / GeV);
    _c[_sqs + "pT3"]->fill(nTransverse);
  }
  if (_sqs == "7000"s && pTlead > 20 * GeV) {
    _h[_sqs + "pT20_Nch"]->fill(nTransverse);
    _h[_sqs + "pT20_Sum"]->fill(ptSumTransverse / GeV);
    _c[_sqs + "pT20"]->fill(nTransverse);
  }
}


/// Normalise histograms etc., after the run
void finalize() {

  for (double eVal : allowedEnergies()) {
    const string en = toString(round(eVal));
    if (_h[en + "pT3_pT"]->sumW()) {
      normalize(_h[en + "pT3_pT"], dbl(*_c[en + "pT3"]) / _h[en + "pT3_Nch"]->sumW());
    }
    if (en == "7000"s && _h[en + "pT20_pT"]->sumW()) {
      normalize(_h[en + "pT20_pT"], dbl(*_c[en + "pT20"]) / _h[en + "pT20_Nch"]->sumW());
    }
  }
  for (auto& item : _h) {
    if (item.first.find("_pT") != string::npos) continue;
    normalize(item.second);
  }
}

private:

/// @{
map<string, CounterPtr> _c;
map<string, Profile1DPtr> _p;
map<string, Histo1DPtr> _h;

string _sqs = "";
/// @}

};

RIVET_DECLARE_ALIASED_PLUGIN(CMS_2011_I916908, CMS_2011_S9120041);

} ```

Aliases: - CMS_2011_S9120041