Rivet analyses

title: CDF_1996_I393345

Properties of high-mass multijet events

Experiment: CDF (Tevatron Run 1)

Inspire ID: 393345

Status: VALIDATED

Authors: - Frank Siegert

References: - Phys.Rev.Lett.75:608-612,1995 - DOI: 10.1103/PhysRevLett.75.608

Beams: p- p+

Beam energies: (900.0, 900.0)GeV

Run details: - Pure QCD events without underlying event (the paper states that UE was corrected for). Several runs with different kinematic cuts might be needed to fill the 2,3,4,5 and 6-jet properly.

Properties of two-, three-, four-, five-, and six-jet events... Multijet-mass, leading jet angle, jet pT.

Source code:CDF_1996_I393345.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/FastJets.hh"

include "Rivet/Projections/FinalState.hh"

include "Rivet/Projections/SmearedJets.hh"

namespace Rivet {

/// @brief CDF properties of high-mass multi-jet events class CDF_1996_I393345 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(CDF_1996_I393345);


/// @name Analysis methods
/// @{

/// Book histograms and initialise projections before the run
void init() {

  /// Initialise and register projections here
  const FinalState fs(Cuts::abseta < 4.2);
  FastJets fj(fs, JetAlg::CDFJETCLU, 0.7);

  // Smear energy and mass with the 10% uncertainty quoted in the paper
  SmearedJets sj_E(fj, [](const Jet& jet) {
    return P4_SMEAR_MASS_GAUSS(P4_SMEAR_E_GAUSS(jet, 0.1 * jet.E()), 0.1 * jet.mass());
  });
  declare(sj_E, "SmearedJets_E");


  /// Book histograms here, e.g.:
  for (size_t i = 0; i < 5; ++i) {
    book(_h_m[i], 1 + i, 1, 1);
    book(_h_costheta[i], 10 + i, 1, 1);
    book(_h_pT[i], 15 + i, 1, 1);
  }
  /// @todo Ratios of mass histograms left out: Binning doesn't work out
}


/// Perform the per-event analysis
void analyze(const Event& event) {
  // Get the smeared jets
  const Jets SJets = apply<JetFinder>(event, "SmearedJets_E").jets(Cuts::Et > 20.0 * GeV, cmpMomByEt);
  if (SJets.size() < 2 || SJets.size() > 6) vetoEvent;

  // Calculate Et, total jet 4 Momentum
  double sumEt(0), sumE(0);
  FourMomentum JS(0, 0, 0, 0);

  for (const Jet& jet : SJets) {
    sumEt += jet.Et() / GeV;
    sumE += jet.E() / GeV;
    JS += jet.momentum();
  }

  if (sumEt < 420. || sumE > 2000.) vetoEvent;

  double mass = JS.mass() / GeV;

  LorentzTransform cms_boost = LorentzTransform::mkFrameTransformFromBeta(JS.betaVec());
  FourMomentum jet0boosted(cms_boost.transform(SJets[0].momentum()));
  double costheta0 = fabs(cos(jet0boosted.theta()));

  if (costheta0 < 2.0 / 3.0) _h_m[SJets.size() - 2]->fill(mass);
  if (mass > 600.) _h_costheta[SJets.size() - 2]->fill(costheta0);
  if (costheta0 < 2.0 / 3.0 && mass > 600.) {
    for (const Jet& jet : SJets) _h_pT[SJets.size() - 2]->fill(jet.pT());
  }
}


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

  /// Normalise, scale and otherwise manipulate histograms here
  for (size_t i = 0; i < 5; ++i) {
    normalize(_h_m[i], 40.0);
    normalize(_h_costheta[i], 2.0);
    normalize(_h_pT[i], 20.0);
  }
}

/// @}

private:

/// @name Histograms
/// @{
Histo1DPtr _h_m[5];
Histo1DPtr _h_costheta[5];
Histo1DPtr _h_pT[5];
/// @}

};

RIVET_DECLARE_ALIASED_PLUGIN(CDF_1996_I393345, CDF_1996_S3108457);

} ```

Aliases: - CDF_1996_S3108457