1// -*- C++ -*-
  2#include "Rivet/Analysis.hh"
  3#include "Rivet/Projections/FinalState.hh"
  4#include "Rivet/Projections/FastJets.hh"
  5#include "Rivet/Projections/LeadingParticlesFinalState.hh"
  6#include "Rivet/Projections/VetoedFinalState.hh"
  7
  8namespace Rivet {
  9
 10
 11  /// @brief CDF angular distribution of prompt photon
 12  class CDF_1993_I354237 : public Analysis {
 13  public:
 14
 15    RIVET_DEFAULT_ANALYSIS_CTOR(CDF_1993_I354237);
 16
 17
 18    void init() {
 19
 20      // The photon selection has been corrected to pTmin=22 GeV (vs. 23 in the trigger)
 21      LeadingParticlesFinalState photonfs(FinalState(Cuts::abseta < 0.9 && Cuts::pT >= 22*GeV));
 22      photonfs.addParticleId(PID::PHOTON);
 23      declare(photonfs, "LeadingPhoton");
 24
 25      // FS excluding the leading photon
 26      VetoedFinalState vfs(FinalState(Cuts::abseta < 4.2));
 27      vfs.addVetoOnThisFinalState(photonfs);
 28      declare(vfs, "VFS");
 29
 30      // Jets
 31      declare(FastJets(vfs, JetAlg::CDFJETCLU, 0.7), "Jets");
 32
 33      book(_h_costheta ,1, 1, 1);
 34
 35    }
 36
 37
 38    void analyze(const Event& event) {
 39
 40      Particles photons = apply<LeadingParticlesFinalState>(event, "LeadingPhoton").particles();
 41      if (photons.size()!=1 || photons[0].pT() > 45.0*GeV) vetoEvent;
 42      FourMomentum leadingPhoton = photons[0].momentum();
 43      double eta_P = leadingPhoton.eta();
 44      double phi_P = leadingPhoton.phi();
 45
 46      // photon isolation: less than 2 GeV EM E_T
 47      double Etsum=0.0;
 48      for (const Particle& p : apply<VetoedFinalState>(event, "VFS").particles()) {
 49        if (p.charge() != 0 && deltaR(eta_P, phi_P, p.eta(), p.phi()) < 0.7) Etsum += p.Et();
 50      }
 51      if (Etsum > 2*GeV) vetoEvent;
 52
 53      FourMomentum jetsum;
 54      Jets jets = apply<FastJets>(event, "Jets").jets(Cuts::pT > 10*GeV, cmpMomByPt);
 55
 56      // Require at least one jet with pT>10 GeV
 57      if (jets.size()==0) vetoEvent;
 58
 59      // Require the leading jet to be in the opposite (phi) hemisphere w.r.t. the photon
 60      if (jets[0].phi() - phi_P <= M_PI) vetoEvent;
 61
 62      // sum all jets in the opposite hemisphere in phi from the photon
 63      for (const Jet& jet : jets) {
 64        if (fabs(jet.phi()-phi_P) > M_PI) jetsum+=jet.momentum();
 65      }
 66
 67      // c.m. cuts, see Table 1
 68      double etaboost = (jetsum.eta()+eta_P)/2.;
 69      if (!inRange(etaboost, -1.2, 1.2)) vetoEvent;
 70
 71      double etastar = (jetsum.eta()-eta_P)/2.;
 72      if (!inRange(etastar, -1.1, 1.1))  vetoEvent;
 73
 74      double pstar = photons[0].pT()*cosh(etastar);
 75      if (!inRange(pstar, 27.8, 47.0)) vetoEvent;
 76
 77      const double costheta = fabs(tanh((eta_P-jetsum.eta())/2.0));
 78      if (!inRange(costheta, 0., 0.8)) vetoEvent;
 79
 80      // Fill histo
 81      _h_costheta->fill(costheta);
 82    }
 83
 84
 85    void finalize() {
 86      /// @todo Take fixed norm direct from ref histo
 87      normalize(_h_costheta, 1.4271); // fixed norm ok
 88    }
 89
 90
 91  private:
 92
 93    Histo1DPtr _h_costheta;
 94
 95  };
 96
 97
 98
 99  RIVET_DECLARE_ALIASED_PLUGIN(CDF_1993_I354237, CDF_1993_S2742446);
100
101}