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 e+ e- > Sigma+ Sigmabar-
 10  class BESIII_2024_I2739177 : public Analysis {
 11  public:
 12
 13    /// Constructor
 14    RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2024_I2739177);
 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(Cuts::abspid==3222), "UFS");
 25      book(_h,"TMP/sigma",refData(1,1,1));
 26    }
 27
 28    void findChildren(const Particle & p,map<long,int> & nRes, int &ncount) {
 29      for(const Particle &child : p.children()) {
 30        if(child.children().empty()) {
 31          nRes[child.pid()]-=1;
 32          --ncount;
 33        }
 34        else
 35          findChildren(child,nRes,ncount);
 36      }
 37    }
 38
 39
 40    /// Perform the per-event analysis
 41    void analyze(const Event& event) {
 42      const FinalState& fs = apply<FinalState>(event, "FS");
 43      // total hadronic and muonic cross sections
 44      map<long,int> nCount;
 45      int ntotal(0);
 46      for (const Particle& p : fs.particles()) {
 47        nCount[p.pid()] += 1;
 48        ++ntotal;
 49      }
 50      // find the Sigmas
 51      const FinalState& ufs = apply<UnstableParticles>(event, "UFS");
 52      for(unsigned int ix=0;ix<ufs.particles().size();++ix) {
 53        const Particle& p1 = ufs.particles()[ix];
 54        bool matched = false;
 55        // check fs
 56        bool fs = true;
 57        for(const Particle & child : p1.children()) {
 58          if(child.pid()==p1.pid()) {
 59            fs = false;
 60            break;
 61          }
 62        }
 63        if(!fs) continue;
 64        // find the children
 65        map<long,int> nRes = nCount;
 66        int ncount = ntotal;
 67        findChildren(p1,nRes,ncount);
 68        for(unsigned int iy=ix+1;iy<ufs.particles().size();++iy) {
 69          const Particle& p2 = ufs.particles()[iy];
 70          if(p2.pid() != -p1.pid()) continue;
 71          // check fs
 72          bool fs = true;
 73          for(const Particle & child : p2.children()) {
 74            if(child.pid()==p2.pid()) {
 75              fs = false;
 76              break;
 77            }
 78          }
 79          if(!fs) continue;
 80          map<long,int> nRes2 = nRes;
 81          int ncount2 = ncount;
 82          findChildren(p2,nRes2,ncount2);
 83          if(ncount2!=0) continue;
 84          matched=true;
 85          for(auto const & val : nRes2) {
 86            if(val.second!=0) {
 87              matched = false;
 88              break;
 89            }
 90          }
 91          if(matched) {
 92            _h->fill(sqrtS()/GeV);
 93            break;
 94          }
 95        }
 96        if(matched) break;
 97      }
 98    }
 99
100
101    /// Normalise histograms etc., after the run
102    void finalize() {
103      scale(_h,crossSection()/ sumOfWeights() /picobarn);
104      Estimate1DPtr tmp;
105      book(tmp,1,1,1);
106      barchart(_h,tmp);
107    }
108
109    /// @}
110
111
112    /// @name Histograms
113    /// @{
114    Histo1DPtr _h;
115    /// @}
116
117
118  };
119
120
121  RIVET_DECLARE_PLUGIN(BESIII_2024_I2739177);
122
123}