1// -*- C++ -*-
  2#include "Rivet/Analysis.hh"
  3#include "Rivet/Projections/Beam.hh"
  4#include "Rivet/Projections/UnstableParticles.hh"
  5
  6namespace Rivet {
  7
  8
  9  /// @brief ARGUS D0, D+, D*+ production
 10  class ARGUS_1991_I315059 : public Analysis {
 11  public:
 12
 13    /// Constructor
 14    RIVET_DEFAULT_ANALYSIS_CTOR(ARGUS_1991_I315059);
 15
 16
 17    /// @name Analysis methods
 18    /// @{
 19
 20    /// Book histograms and initialise projections before the run
 21    void init() {
 22
 23      // Initialise and register projections
 24      declare(UnstableParticles(), "UFS");
 25      declare(Beam(), "Beams");
 26
 27      // Book histograms
 28      book(_n_D0   , 1,1,1);
 29      book(_n_Dp   , 1,1,2);
 30      book(_n_DStar, 1,1,3);
 31
 32      book(_h_x_D0   , 2,1,1);
 33      book(_h_x_Dp   , 3,1,1);
 34      book(_h_x_DStar, 4,1,1);
 35
 36      book(_h_p_D0   , 5,1,1);
 37      book(_h_p_Dp   , 6,1,1);
 38      book(_h_p_DStar, 7,1,1);
 39
 40      book(_c_cont, "/TMP/c_cont");
 41      book(_c_ups , "/TMP/c_ups");
 42    }
 43
 44
 45    /// Perform the per-event analysis
 46    void analyze(const Event& event) {
 47      // Get beams and average beam momentum
 48      const ParticlePair& beams = apply<Beam>(event, "Beams").beams();
 49      const double meanBeamMom = ( beams.first.p3().mod() +
 50                                   beams.second.p3().mod() ) / 2.0;
 51      MSG_DEBUG("Avg beam momentum = " << meanBeamMom);
 52      // Find the Upsilon(4S) among the unstables
 53      const UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");
 54      Particles upsilons = ufs.particles(Cuts::pid==300553);
 55      // Continuum
 56      if (upsilons.empty()) {
 57        _c_cont->fill();
 58        MSG_DEBUG("No Upsilons found => continuum event");
 59        for (const Particle &p : ufs.particles(Cuts::abspid==411 or Cuts::abspid==421 or Cuts::abspid==413)) {
 60          double xp = p.p3().mod()/sqrt(sqr(meanBeamMom)+sqr(p.mass()));
 61          if(p.abspid()==421) {
 62            _h_x_D0->fill(xp);
 63            _n_D0->fill(Ecms);
 64          }
 65          else if(p.abspid()==411) {
 66            _h_x_Dp->fill(xp);
 67            _n_Dp->fill(Ecms);
 68          }
 69          else if(p.abspid()==413) {
 70            _h_x_DStar->fill(xp);
 71            _n_DStar->fill(Ecms);
 72          }
 73        }
 74      }
 75      // upsilon decay
 76      else {
 77        for (const Particle& ups : upsilons) {
 78          _c_ups->fill();
 79          Particles unstable;
 80          // Find the decay products we want
 81          findDecayProducts(ups, unstable);
 82          // boost to rest frame (if required)
 83          LorentzTransform cms_boost;
 84          if (ups.p3().mod() > 1*MeV) {
 85            cms_boost = LorentzTransform::mkFrameTransformFromBeta(ups.momentum().betaVec());
 86          }
 87          for (const Particle& p : unstable) {
 88            const FourMomentum p2 = cms_boost.transform(p.momentum());
 89            double modp = p2.p3().mod();
 90            if(p.abspid()==421) {
 91              _h_p_D0->fill(modp);
 92            }
 93            else if(p.abspid()==411) {
 94              _h_p_Dp->fill(modp);
 95            }
 96            else if(p.abspid()==413) {
 97              _h_p_DStar->fill(modp);
 98            }
 99          }
100        }
101      }
102    }
103
104    /// Recursively walk the decay tree to find decay products of @a p
105    void findDecayProducts(Particle mother, Particles& unstable) {
106      for(const Particle & p: mother.children()) {
107        const int id = p.abspid();
108        if (id == 411 || id == 421) {
109          unstable.push_back(p);
110        }
111        else if (id == 413 ) {
112          unstable.push_back(p);
113          findDecayProducts(p, unstable);
114        }
115        else if(!p.children().empty()) {
116          findDecayProducts(p, unstable);
117        }
118      }
119    }
120
121    /// Normalise histograms etc., after the run
122    void finalize() {
123      // brs for the decays used (PDG 2018)
124      double brD0 = 0.0389;
125      double brDp = 0.0898;
126      double brDStar = 0.677;
127      if (_c_cont->numEntries()!=0) {
128        scale(_n_D0      , 1./sumOfWeights()*crossSection()/nanobarn);
129        scale(_n_Dp      , 1./sumOfWeights()*crossSection()/nanobarn);
130        scale(_n_DStar  ,  1./sumOfWeights()*crossSection()/nanobarn);
131        scale(_h_x_D0   , brD0/sumOfWeights()*crossSection()/nanobarn*sqr(sqrtS()));
132        scale(_h_x_Dp   , brDp/sumOfWeights()*crossSection()/nanobarn*sqr(sqrtS()));
133        scale(_h_x_DStar, brD0*brDStar/sumOfWeights()*crossSection()/nanobarn*sqr(sqrtS()));
134      }
135      if (_c_ups->numEntries()!=0) {
136        scale(_h_p_D0   , 1e3*0.5*brD0/ *_c_ups);
137        scale(_h_p_Dp   , 1e3*0.5*brDp/ *_c_ups);
138        scale(_h_p_DStar, 1e3*0.5*brD0*brDStar/ *_c_ups);
139      }
140    }
141
142    /// @}
143
144
145    /// @name Histograms
146    /// @{
147    BinnedHistoPtr<string> _n_D0,_n_Dp,_n_DStar;
148    Histo1DPtr _h_x_D0,_h_x_Dp,_h_x_DStar;
149    Histo1DPtr _h_p_D0,_h_p_Dp,_h_p_DStar;
150    CounterPtr _c_cont, _c_ups;
151    const string Ecms = "10.6";
152    /// @}
153
154
155  };
156
157
158  RIVET_DECLARE_PLUGIN(ARGUS_1991_I315059);
159
160
161}