1// -*- C++ -*-
  2#include "Rivet/Analysis.hh"
  3#include "Rivet/Projections/FinalState.hh"
  4#include "Rivet/Projections/UnstableParticles.hh"
  5
  6namespace Rivet {
  7
  8
  9  /// @brief gamma gamma -> pi+pi-pi0
 10  class ARGUS_1997_I420421 : public Analysis {
 11  public:
 12
 13    /// Constructor
 14    RIVET_DEFAULT_ANALYSIS_CTOR(ARGUS_1997_I420421);
 15
 16
 17    /// @name Analysis methods
 18    /// @{
 19
 20    /// Book histograms and initialise projections before the run
 21    void init() {
 22      // Initialise and register projections
 23      declare(FinalState(), "FS");
 24      declare(UnstableParticles(), "UFS");
 25      // book histos
 26      if (inRange(sqrtS()/GeV, 0.8, 2.1)) {
 27        for (unsigned int ix=0; ix<5; ++ix) {
 28          book(_nMeson[ix], "TMP/nMeson_"+toString(ix+1));
 29        }
 30      }
 31      else {
 32        throw Error("Invalid CMS energy for ARGUS_1997_I420421");
 33      }
 34    }
 35
 36    void findChildren(const Particle & p,map<long,int> & nRes, int &ncount) {
 37      for (const Particle &child : p.children()) {
 38        if (child.children().empty()) {
 39          nRes[child.pid()]-=1;
 40          --ncount;
 41        }
 42        else {
 43          findChildren(child,nRes,ncount);
 44        }
 45      }
 46    }
 47
 48    /// Perform the per-event analysis
 49    void analyze(const Event& event) {
 50      const FinalState& fs = apply<FinalState>(event, "FS");
 51      // find the final-state particles
 52      map<long,int> nCount;
 53      int ntotal(0);
 54      for (const Particle& p : fs.particles()) {
 55        nCount[p.pid()] += 1;
 56        ++ntotal;
 57      }
 58      // check the 3 meson final state
 59      if (ntotal!=3) vetoEvent;
 60      if ( nCount[PID::PI0]==1 && nCount[PID::PIPLUS]==1 && nCount[PID::PIMINUS]==1 ) {
 61        _nMeson[0]->fill();
 62      }
 63      else  vetoEvent;
 64      // now the intermediate states
 65      const UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");
 66      // f0 and f2 mesons and rho
 67      bool nonRes=true;
 68      for (const Particle & p : ufs.particles(Cuts::pid==225 ||
 69                                              Cuts::pid==9010221 ||
 70                                              Cuts::abspid==213)) {
 71       	map<long,int> nRes=nCount;
 72       	int ncount = ntotal;
 73       	findChildren(p,nRes,ncount);
 74        int sign = p.pid()/p.abspid();
 75        // id of the pion not from the resonance decay
 76        int idother = p.abspid()==213 ? -sign*211 : 111;
 77        bool matched=true;
 78        for (const auto& val : nRes) {
 79          if (val.first==idother) {
 80            if (val.second!=1) {
 81              matched = false;
 82              break;
 83            }
 84          }
 85          else {
 86            if (val.second!=0) {
 87              matched = false;
 88              break;
 89            }
 90          }
 91        }
 92        if (matched) {
 93          nonRes=false;
 94          if (p.abspid()==213) {
 95            _nMeson[2]->fill();
 96          }
 97          else if (p.pid()==225) {
 98            _nMeson[3]->fill();
 99          }
100          else {
101            _nMeson[4]->fill();
102          }
103          break;
104        }
105      }
106      if (nonRes) _nMeson[1]->fill();
107    }
108
109
110    /// Normalise histograms etc., after the run
111    void finalize() {
112      scale(_nMeson, crossSection()/nanobarn/sumOfWeights());
113      // loop over tables in paper
114      for (unsigned int ix=0; ix<5; ++ix) {
115        unsigned int iy=1;
116        if (ix==2) iy=5;
117        else if (ix==3) iy=3;
118        Estimate1DPtr mult;
119        book(mult, ix+1, 1, iy);
120        for (auto& b : mult->bins()) {
121          if (inRange(sqrtS()/MeV, b.xMin(), b.xMax())) {
122            b.setVal(_nMeson[ix]->val());
123            b.setErr(_nMeson[ix]->err());
124          }
125        }
126      }
127    }
128
129    /// @}
130
131
132    /// @name Histograms
133    /// @{
134    CounterPtr _nMeson[5];
135    /// @}
136
137
138  };
139
140
141  RIVET_DECLARE_PLUGIN(ARGUS_1997_I420421);
142
143}