Rivet analyses

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: - pp̄→ jets at 1800~

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++ -*-
#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