Rivet analyses

title: D0_1996_I416886

Azimuthal decorrelation of jets widely separated in rapidity

Experiment: D0 (Tevatron Run 1)

Inspire ID: 416886

Status: VALIDATED

Authors: - Frank Siegert

References: - Phys.Rev.Lett.77:595-600,1996 - DOI: 10.1103/PhysRevLett.77.595 - arXiv: hep-ex/9603010

Beams: p- p+

Beam energies: (900.0, 900.0)GeV

Run details: - $p \bar{p} \to \,\text{jets}$ at 1800~\GeV

First measurement of the azimuthal decorrelation between jets with pseudorapidity separation up to five units. The data were accumulated using the D0 detector during Tevatron Run 1 at $\sqrt{s} = 1.8~\TeV$. Requires di-jet events with at least one jet above 50 GeV and two jets above 20 GeV.

Source code:D0_1996_I416886.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/FastJets.hh"

include "Rivet/Projections/FinalState.hh"

namespace Rivet {

/// D0 azimuthal correlation of jets widely separated in rapidity class D0_1996_I416886 : public Analysis { public:

RIVET_DEFAULT_ANALYSIS_CTOR(D0_1996_I416886);


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

void init() {
  const FinalState fs;
  declare(fs, "FS");
  /// @todo Use correct jet algorithm
  declare(FastJets(fs, JetAlg::D0ILCONE, 0.7), "ConeJets");

  book(_h_deta, 1, 1, 1);
  book(_h_dphi, {0., 2., 4., 6.}, {"d02-x01-y01", "d02-x01-y02", "d02-x01-y03"});
  book(_h_cosdphi_deta, 3, 1, 1);
}


void analyze(const Event& event) {

  Jets jets = apply<FastJets>(event, "ConeJets")
                  .jets(Cuts::Et > 20 * GeV && Cuts::abseta < 3, cmpMomByEt);

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

  FourMomentum minjet = jets[0].momentum();
  FourMomentum maxjet = jets[1].momentum();
  double mineta = minjet.eta();
  double maxeta = maxjet.eta();

  for (const Jet& jet : jets) {
    double eta = jet.eta();
    if (eta < mineta) {
      minjet = jet.momentum();
      mineta = eta;
    }
    else if (eta > maxeta) {
      maxjet = jet.momentum();
      maxeta = eta;
    }
  }

  if (minjet.Et() < 50 * GeV && maxjet.Et() < 50.0 * GeV) vetoEvent;

  double deta = maxjet.eta() - minjet.eta();
  double dphi = mapAngle0To2Pi(maxjet.phi() - minjet.phi());

  _h_deta->fill(deta);
  _h_dphi->fill(deta, 1.0 - dphi / M_PI);
  _h_cosdphi_deta->fill(deta, cos(M_PI - dphi));
}


void finalize() {
  // Normalised to #events
  normalize(_h_deta, 8830.); // fixed norm OK

  // Normalied to 1/(4pi)
  normalize(_h_dphi, 1. / (4. * M_PI));
}

/// @}

private:

/// @name Histograms
/// @{
Histo1DPtr _h_deta;
Histo1DGroupPtr _h_dphi;
Profile1DPtr _h_cosdphi_deta;
/// @}

};

RIVET_DECLARE_ALIASED_PLUGIN(D0_1996_I416886, D0_1996_S3324664);

} ```

Aliases: - D0_1996_S3324664