Rivet analyses

Cross-sections for light hadrons at 3.650 and 3.773 GeV

Experiment: BESII (BEPC)

Inspire ID: 762901

Status: VALIDATED

Authors: - Peter Richardson

References: - Phys.Lett. B656 (2007) 30-37, 2007

Beams: e+ e-

Beam energies: (1.8, 1.8); (1.9, 1.9)GeV

Run details: - e+e- to hadrons

Cross section for e⁺e⁻ → 2π⁺2π⁻K⁺K⁻, π⁺π⁻2K⁺2K⁻, 2π⁺2π⁻pp̄, 3π⁺3π⁻, 2π⁺2π⁻K⁺K⁻π⁰, ρ⁰π⁺π⁻, ρ⁰K⁺K⁻, ρ⁰pp̄, K^*0K⁻π⁺ + c.c. at 3.650 and 3.773 GeV.

Source code:`BESII_2007_I762901.cc`

// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/FinalState.hh"
#include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {


  /// @brief Cross-sections for light hadrons at 3.650 and 3.773 GeV
  class BESII_2007_I762901 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(BESII_2007_I762901);


    /// @name Analysis methods
    /// @{

    /// Book histograms and initialise projections before the run
    void init() {

      // Initialise and register projections
      declare(FinalState(), "FS");
      declare(UnstableParticles(), "UFS");

      // Book histograms
      for (size_t ix = 1; ix < 11; ++ix) {
        if (ix == 6) continue;
        book(_nMeson[ix], 1, 1, ix);
      }
      for (const string& en : _nMeson[1].binning().edges<0>()) {
        const double eval = stod(en) * GeV;
        if (isCompatibleWithSqrtS(eval)) {
          _sqs = en;
          break;
        }
      }
      raiseBeamErrorIf(_sqs.empty());
    }

    void findChildren(const Particle& p, map<long, int>& nRes, int& ncount) const {
      for (const Particle& child : p.children()) {
        if (child.children().empty()) {
          nRes[child.pid()] -= 1;
          --ncount;
        }
        else {
          findChildren(child, nRes, ncount);
        }
      }
    }

    /// Perform the per-event analysis
    void analyze(const Event& event) {
      const FinalState& fs = apply<FinalState>(event, "FS");

      map<long, int> nCount;
      int ntotal(0);
      for (const Particle& p : fs.particles()) {
        nCount[p.pid()] += 1;
        ++ntotal;
      }
      if (ntotal == 6) {
        if (nCount[211] == 2 && nCount[-211] == 2 && nCount[321] == 1 && nCount[-321] == 1)
          _nMeson[1]->fill(_sqs);
        else if (nCount[211] == 1 && nCount[-211] == 1 && nCount[321] == 2 && nCount[-321] == 2) {
          if (_sqs == "3.773") _nMeson[2]->fill(_sqs);
        }
        else if (nCount[211] == 2 && nCount[-211] == 2 && nCount[2212] == 1 && nCount[-2212] == 1)
          _nMeson[3]->fill(_sqs);
        else if (nCount[211] == 3 && nCount[-211] == 3)
          _nMeson[4]->fill(_sqs);
      }
      else if (ntotal == 7) {
        if (nCount[211] == 2 && nCount[-211] == 2 && nCount[321] == 1 && nCount[-321] == 1
            && nCount[111] == 1)
          _nMeson[5]->fill(_sqs);
      }
      const FinalState& ufs = apply<FinalState>(event, "UFS");
      for (const Particle& p : ufs.particles()) {
        if (p.children().empty()) continue;
        if (p.pid() != 113 && p.abspid() != 313) continue;
        map<long, int> nRes = nCount;
        int ncount = ntotal;
        findChildren(p, nRes, ncount);
        if (p.pid() == 113) {
          if (ncount != 2) continue;
          unsigned int nPi(0), nK(0), nProt(0);
          bool matched = true;
          for (const auto& val : nRes) {
            if (abs(val.first) == 211 && val.second == 1) {
              nPi += 1;
            }
            else if (abs(val.first) == 321 && val.second == 1) {
              nK += 1;
            }
            else if (abs(val.first) == 2212 && val.second == 1) {
              nProt += 1;
            }
            else if (val.second != 0) {
              matched = false;
              break;
            }
          }
          if (matched) {
            if (nProt == 2 && nPi == 0 && nK == 0)
              _nMeson[9]->fill(_sqs);
            else if (nProt == 0 && nPi == 2 && nK == 0)
              _nMeson[7]->fill(_sqs);
            else if (nProt == 0 && nPi == 0 && nK == 2)
              _nMeson[8]->fill(_sqs);
          }
        }
        else if (p.abspid() == 313) {
          if (ncount != 2) continue;
          unsigned int npi(0), nK(0);
          bool matched = true;
          int ipi = p.pid() == 313 ? 211 : -211;
          int iK = p.pid() == 313 ? -321 : 321;
          for (const auto& val : nRes) {
            if (abs(val.first) == ipi && val.second == 1) {
              npi += 1;
            }
            else if (abs(val.first) == iK && val.second == 1) {
              nK += 1;
            }
            else if (val.second != 0) {
              matched = false;
              break;
            }
          }
          if (matched) {
            if (npi == 1 && nK == 1) _nMeson[10]->fill(_sqs);
          }
        }
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      scale(_nMeson, crossSection() / sumOfWeights() / picobarn);
    }

    /// @}


    /// @name Histograms
    /// @{
    map<int, BinnedHistoPtr<string>> _nMeson;
    string _sqs = "";
    /// @}
  };


  RIVET_DECLARE_PLUGIN(BESII_2007_I762901);

}

Rivet analyses

Cross-sections for light hadrons at 3.650 and 3.773 GeV

Source code:BESII_2007_I762901.cc

Source code:`BESII_2007_I762901.cc`