Rivet analyses

// -*- 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_I418504 : public Analysis {
  public:

    RIVET_DEFAULT_ANALYSIS_CTOR(CDF_1996_I418504);


    /// @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);
      declare(fj, "Jets");

      // 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");

      /// Book histograms here, e.g.:
      book(_h_3_mNJ, 1, 1, 1);
      book(_h_3_X3, 2, 1, 1);
      book(_h_3_X4, 3, 1, 1);
      book(_h_3_costheta3, 8, 1, 1);
      book(_h_3_psi3, 9, 1, 1);
      book(_h_3_f3, 14, 1, 1);
      book(_h_3_f4, 14, 1, 2);
      book(_h_3_f5, 14, 1, 3);

      book(_h_4_mNJ, 1, 1, 2);
      book(_h_4_X3, 4, 1, 1);
      book(_h_4_X4, 5, 1, 1);
      book(_h_4_costheta3, 10, 1, 1);
      book(_h_4_psi3, 11, 1, 1);
      book(_h_4_f3, 15, 1, 1);
      book(_h_4_f4, 15, 1, 2);
      book(_h_4_f5, 15, 1, 3);
      book(_h_4_XA, 17, 1, 1);
      book(_h_4_psiAB, 19, 1, 1);
      book(_h_4_fA, 21, 1, 1);
      book(_h_4_fB, 21, 1, 2);

      book(_h_5_mNJ, 1, 1, 3);
      book(_h_5_X3, 6, 1, 1);
      book(_h_5_X4, 7, 1, 1);
      book(_h_5_costheta3, 12, 1, 1);
      book(_h_5_psi3, 13, 1, 1);
      book(_h_5_f3, 16, 1, 1);
      book(_h_5_f4, 16, 1, 2);
      book(_h_5_f5, 16, 1, 3);
      book(_h_5_XA, 18, 1, 1);
      book(_h_5_XC, 18, 1, 2);
      book(_h_5_psiAB, 20, 1, 1);
      book(_h_5_psiCD, 20, 1, 2);
      book(_h_5_fA, 22, 1, 1);
      book(_h_5_fB, 23, 1, 1);
      book(_h_5_fC, 24, 1, 1);
      book(_h_5_fD, 25, 1, 1);
    }


    void analyze(const Event& event) {
      Jets jets;
      FourMomentum jetsystem(0.0, 0.0, 0.0, 0.0);
      for (const Jet& jet : apply<JetFinder>(event, "SmearedJets").jets(Cuts::Et > 20.0 * GeV, cmpMomByEt)) {
        bool separated = true;
        for (const Jet& ref : jets) {
          if (deltaR(jet, ref) < 0.9) {
            separated = false;
            break;
          }
        }
        if (!separated) continue;
        jets.push_back(jet);
        jetsystem += jet.momentum();
        if (jets.size() >= 5) break;
      }

      if (jets.size() > 4) {
        _fiveJetAnalysis(jets);
        jets.resize(4);
      }
      if (jets.size() > 3) {
        _fourJetAnalysis(jets);
        jets.resize(3);
      }
      if (jets.size() > 2) {
        _threeJetAnalysis(jets);
      }
    }


    void _threeJetAnalysis(const Jets& jets) {
      MSG_DEBUG("3 jet analysis");

      double sumEt = 0.0;
      FourMomentum jetsystem(0.0, 0.0, 0.0, 0.0);
      for (const Jet& jet : jets) {
        sumEt += jet.Et();
        jetsystem += jet.momentum();
      }
      if (sumEt < 420.0 * GeV) return;

      const double m3J = _safeMass(jetsystem);
      if (m3J < 600 * GeV) return;

      const LorentzTransform cms_boost = LorentzTransform::mkFrameTransformFromBeta(jetsystem.betaVec());
      vector<FourMomentum> jets3;
      for (Jet jet : jets) {
        jets3.push_back(cms_boost.transform(jet.momentum()));
      }
      isortBy(jets3, cmpMomByE);
      FourMomentum p3(jets3[0]), p4(jets3[1]), p5(jets3[2]);

      FourMomentum pAV = cms_boost.transform(_avg_beam_in_lab(m3J, jetsystem.rapidity()));
      double costheta3 = pAV.p3().unit().dot(p3.p3().unit());
      if (fabs(costheta3) > 0.6) return;

      double X3 = 2.0 * p3.E() / m3J;
      if (X3 > 0.9) return;

      const double X4 = 2.0 * p4.E() / m3J;
      const double psi3 = _psi(p3, pAV, p4, p5);
      const double f3 = _safeMass(p3) / m3J;
      const double f4 = _safeMass(p4) / m3J;
      const double f5 = _safeMass(p5) / m3J;

      _h_3_mNJ->fill(m3J);
      _h_3_X3->fill(X3);
      _h_3_X4->fill(X4);
      _h_3_costheta3->fill(costheta3);
      _h_3_psi3->fill(psi3);
      _h_3_f3->fill(f3);
      _h_3_f4->fill(f4);
      _h_3_f5->fill(f5);
    }


    void _fourJetAnalysis(const Jets& jets) {
      MSG_DEBUG("4 jet analysis");

      double sumEt = 0.0;
      FourMomentum jetsystem(0.0, 0.0, 0.0, 0.0);
      for (const Jet& jet : jets) {
        sumEt += jet.Et();
        jetsystem += jet.momentum();
      }
      if (sumEt < 420.0 * GeV) return;

      const double m4J = _safeMass(jetsystem);
      if (m4J < 650 * GeV) return;

      const LorentzTransform cms_boost = LorentzTransform::mkFrameTransformFromBeta(jetsystem.betaVec());
      vector<FourMomentum> jets4;
      for (Jet jet : jets) {
        jets4.push_back(cms_boost.transform(jet.momentum()));
      }
      isortBy(jets4, cmpMomByE);

      FourMomentum pA, pB;
      vector<FourMomentum> jets3(_reduce(jets4, pA, pB));
      isortBy(jets3, cmpMomByE);
      FourMomentum p3(jets3[0]);
      FourMomentum p4(jets3[1]);
      FourMomentum p5(jets3[2]);

      FourMomentum pAV = cms_boost.transform(_avg_beam_in_lab(m4J, jetsystem.rapidity()));
      double costheta3 = pAV.p3().unit().dot(p3.p3().unit());
      if (fabs(costheta3) > 0.8) {
        return;
      }

      const double X3 = 2.0 * p3.E() / m4J;
      if (X3 > 0.9) {
        return;
      }

      // fill histograms
      const double X4 = 2.0 * p4.E() / m4J;
      const double psi3 = _psi(p3, pAV, p4, p5);
      const double f3 = _safeMass(p3) / m4J;
      const double f4 = _safeMass(p4) / m4J;
      const double f5 = _safeMass(p5) / m4J;
      const double fA = _safeMass(pA) / m4J;
      const double fB = _safeMass(pB) / m4J;
      const double XA = pA.E() / (pA.E() + pB.E());
      const double psiAB = _psi(pA, pB, pA + pB, pAV);

      _h_4_mNJ->fill(m4J);
      _h_4_X3->fill(X3);
      _h_4_X4->fill(X4);
      _h_4_costheta3->fill(costheta3);
      _h_4_psi3->fill(psi3);
      _h_4_f3->fill(f3);
      _h_4_f4->fill(f4);
      _h_4_f5->fill(f5);
      _h_4_XA->fill(XA);
      _h_4_psiAB->fill(psiAB);
      _h_4_fA->fill(fA);
      _h_4_fB->fill(fB);
    }


    void _fiveJetAnalysis(const Jets& jets) {
      MSG_DEBUG("5 jet analysis");

      double sumEt = 0.0;
      FourMomentum jetsystem(0.0, 0.0, 0.0, 0.0);
      for (const Jet& jet : jets) {
        sumEt += jet.Et();
        jetsystem += jet.momentum();
      }
      if (sumEt < 420.0 * GeV) return;

      const double m5J = _safeMass(jetsystem);
      if (m5J < 750 * GeV) return;

      const LorentzTransform cms_boost = LorentzTransform::mkFrameTransformFromBeta(jetsystem.betaVec());
      vector<FourMomentum> jets5;
      for (Jet jet : jets) {
        jets5.push_back(cms_boost.transform(jet.momentum()));
      }
      isortBy(jets5, cmpMomByE);

      FourMomentum pC, pD;
      vector<FourMomentum> jets4(_reduce(jets5, pC, pD));
      isortBy(jets4, cmpMomByE);

      FourMomentum pA, pB;
      vector<FourMomentum> jets3(_reduce(jets4, pA, pB));
      isortBy(jets3, cmpMomByE);
      FourMomentum p3(jets3[0]);
      FourMomentum p4(jets3[1]);
      FourMomentum p5(jets3[2]);

      // fill histograms
      FourMomentum pAV = cms_boost.transform(_avg_beam_in_lab(m5J, jetsystem.rapidity()));
      const double costheta3 = pAV.p3().unit().dot(p3.p3().unit());
      const double X3 = 2.0 * p3.E() / m5J;
      const double X4 = 2.0 * p4.E() / m5J;
      const double psi3 = _psi(p3, pAV, p4, p5);
      const double f3 = _safeMass(p3) / m5J;
      const double f4 = _safeMass(p4) / m5J;
      const double f5 = _safeMass(p5) / m5J;
      const double fA = _safeMass(pA) / m5J;
      const double fB = _safeMass(pB) / m5J;
      const double XA = pA.E() / (pA.E() + pB.E());
      const double psiAB = _psi(pA, pB, pA + pB, pAV);
      const double fC = _safeMass(pC) / m5J;
      const double fD = _safeMass(pD) / m5J;
      const double XC = pC.E() / (pC.E() + pD.E());
      const double psiCD = _psi(pC, pD, pC + pD, pAV);

      _h_5_mNJ->fill(m5J);
      _h_5_X3->fill(X3);
      _h_5_X4->fill(X4);
      _h_5_costheta3->fill(costheta3);
      _h_5_psi3->fill(psi3);
      _h_5_f3->fill(f3);
      _h_5_f4->fill(f4);
      _h_5_f5->fill(f5);
      _h_5_XA->fill(XA);
      _h_5_psiAB->fill(psiAB);
      _h_5_fA->fill(fA);
      _h_5_fB->fill(fB);
      _h_5_XC->fill(XC);
      _h_5_psiCD->fill(psiCD);
      _h_5_fC->fill(fC);
      _h_5_fD->fill(fD);
    }


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

      /// Normalise, scale and otherwise manipulate histograms here
      normalize(_h_3_mNJ);
      normalize(_h_3_X3);
      normalize(_h_3_X4);
      normalize(_h_3_costheta3);
      normalize(_h_3_psi3);
      normalize(_h_3_f3);
      normalize(_h_3_f4);
      normalize(_h_3_f5);

      normalize(_h_4_mNJ);
      normalize(_h_4_X3);
      normalize(_h_4_X4);
      normalize(_h_4_costheta3);
      normalize(_h_4_psi3);
      normalize(_h_4_f3);
      normalize(_h_4_f4);
      normalize(_h_4_f5);
      normalize(_h_4_XA);
      normalize(_h_4_psiAB);
      normalize(_h_4_fA);
      normalize(_h_4_fB);

      normalize(_h_5_mNJ);
      normalize(_h_5_X3);
      normalize(_h_5_X4);
      normalize(_h_5_costheta3);
      normalize(_h_5_psi3);
      normalize(_h_5_f3);
      normalize(_h_5_f4);
      normalize(_h_5_f5);
      normalize(_h_5_XA);
      normalize(_h_5_XC);
      normalize(_h_5_psiAB);
      normalize(_h_5_psiCD);
      normalize(_h_5_fA);
      normalize(_h_5_fB);
      normalize(_h_5_fC);
      normalize(_h_5_fD);
    }

    /// @}


  private:

    vector<FourMomentum> _reduce(const vector<FourMomentum>& jets,
                                 FourMomentum& combined1,
                                 FourMomentum& combined2) {
      double minMass2 = 1e9;
      size_t idx1(jets.size()), idx2(jets.size());
      for (size_t i = 0; i < jets.size(); ++i) {
        for (size_t j = i + 1; j < jets.size(); ++j) {
          double mass2 = FourMomentum(jets[i] + jets[j]).mass2();
          if (mass2 < minMass2) {
            idx1 = i;
            idx2 = j;
          }
        }
      }
      vector<FourMomentum> newjets;
      for (size_t i = 0; i < jets.size(); ++i) {
        if (i != idx1 && i != idx2) newjets.push_back(jets[i]);
      }
      newjets.push_back(jets[idx1] + jets[idx2]);
      combined1 = jets[idx1];
      combined2 = jets[idx2];
      return newjets;
    }


    FourMomentum _avg_beam_in_lab(const double& m, const double& y) {
      const double mt = m / 2.0;
      FourMomentum beam1(mt, 0, 0, mt);
      FourMomentum beam2(mt, 0, 0, -mt);
      if (fabs(y) > 1e-3) {
        FourMomentum boostvec(cosh(y), 0.0, 0.0, sinh(y));
        const LorentzTransform cms_boost = LorentzTransform::mkFrameTransformFromBeta(boostvec.betaVec())
                                               .inverse();
        beam1 = cms_boost.transform(beam1);
        beam2 = cms_boost.transform(beam2);
      }
      return (beam1.E() > beam2.E()) ? beam1 - beam2 : beam2 - beam1;
    }


    double _psi(const FourMomentum& p1,
                const FourMomentum& p2,
                const FourMomentum& p3,
                const FourMomentum& p4) {
      Vector3 p1xp2 = p1.p3().cross(p2.p3());
      Vector3 p3xp4 = p3.p3().cross(p4.p3());
      return mapAngle0ToPi(acos(p1xp2.unit().dot(p3xp4.unit())));
    }


    double _safeMass(const FourMomentum& p) {
      double mass2 = p.mass2();
      if (mass2 > 0.0)
        return sqrt(mass2);
      else if (mass2 < -1e-5) {
        MSG_WARNING("m2 = " << mass2 / GeV << " GeV. Assuming m2 = 0.");
        return 0.0;
      }
      else
        return 0.0;
    }


  private:

    /// @name Histograms
    /// @{
    Histo1DPtr _h_3_mNJ;
    Histo1DPtr _h_3_X3;
    Histo1DPtr _h_3_X4;
    Histo1DPtr _h_3_costheta3;
    Histo1DPtr _h_3_psi3;
    Histo1DPtr _h_3_f3;
    Histo1DPtr _h_3_f4;
    Histo1DPtr _h_3_f5;

    Histo1DPtr _h_4_mNJ;
    Histo1DPtr _h_4_X3;
    Histo1DPtr _h_4_X4;
    Histo1DPtr _h_4_costheta3;
    Histo1DPtr _h_4_psi3;
    Histo1DPtr _h_4_f3;
    Histo1DPtr _h_4_f4;
    Histo1DPtr _h_4_f5;
    Histo1DPtr _h_4_XA;
    Histo1DPtr _h_4_psiAB;
    Histo1DPtr _h_4_fA;
    Histo1DPtr _h_4_fB;

    Histo1DPtr _h_5_mNJ;
    Histo1DPtr _h_5_X3;
    Histo1DPtr _h_5_X4;
    Histo1DPtr _h_5_costheta3;
    Histo1DPtr _h_5_psi3;
    Histo1DPtr _h_5_f3;
    Histo1DPtr _h_5_f4;
    Histo1DPtr _h_5_f5;
    Histo1DPtr _h_5_XA;
    Histo1DPtr _h_5_XC;
    Histo1DPtr _h_5_psiAB;
    Histo1DPtr _h_5_psiCD;
    Histo1DPtr _h_5_fA;
    Histo1DPtr _h_5_fB;
    Histo1DPtr _h_5_fC;
    Histo1DPtr _h_5_fD;
    /// @}
  };


  RIVET_DECLARE_ALIASED_PLUGIN(CDF_1996_I418504, CDF_1996_S3349578);

}