Rivet analyses

Cross sections for e⁺e⁻ → K_S⁰K⁻K⁻K⁺π⁺, K_S⁰K⁻π⁺η, K_S⁰K⁻ρ⁺, K_S⁰K⁻π⁺ρ⁰ at 3.65 and 3.773 GeV

Experiment: BESII (BEPC)

Inspire ID: 835937

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Eur.Phys.J.C 64 (2009) 243-250

Beams: e+ e-

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

Run details: - e+ e- > hadrons, pi0 qand KS0 set stable

Measurement of the cross sections for e⁺e⁻ → K_S⁰K⁻K⁻K⁺π⁺, K_S⁰K⁻π⁺η, K_S⁰K⁻ρ⁺, K_S⁰K⁻π⁺ρ⁰ at 3.65 and 3.773 GeV.

Source code:`BESII_2009_I835937.cc`

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

namespace Rivet {


  /// @brief e+e- > light hadrons including KS0
  class BESII_2009_I835937 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(BESII_2009_I835937);


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

    /// Book histograms and initialise projections before the run
    void init() {
      // Initialise and register projections
      declare(FinalState(), "FS");
      declare(UnstableParticles(), "UFS");

      if (isCompatibleWithSqrtS(3.65))
        _sqs = "3.65";
      else if (isCompatibleWithSqrtS(3.773)) {
        _sqs = "3.773";
        book(_sigma[1], 1, 1, 2);
      }
      raiseBeamErrorIf(_sqs.empty());
      for (size_t ix = 0; ix < 7; ++ix) {
        if (ix > 0 && ix < 5) continue;
        book(_sigma[ix], 1, 1, 1 + ix);
      }
    }

    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;
      }
      const FinalState& ufs = apply<FinalState>(event, "UFS");
      // first the purely FS particles
      if (ntotal == 5 && nCount[310] == 1
          && ((nCount[-321] == 2 && nCount[321] == 1 && nCount[211] == 1)
              || (nCount[321] == 2 && nCount[-321] == 1 && nCount[-211] == 1))) {
        _sigma[0]->fill(_sqs);
      }

      // loop over unstable particles
      for (const Particle& p : ufs.particles(Cuts::pid == 221 || Cuts::pid == 113 || Cuts::abspid == 213)) {
        if (p.children().empty()) continue;
        map<long, int> nRes = nCount;
        int ncount = ntotal;
        findChildren(p, nRes, ncount);
        // eta /rho0
        bool matched = false;
        if (p.pid() == 221 || p.pid() == 113) {
          if (ncount == 3) {
            matched = true;
            for (const auto& val : nRes) {
              if (abs(val.first) == 310) {
                if (val.second != 1) {
                  matched = false;
                  break;
                }
              }
              else if (abs(val.first) == 211) {
                if (val.second != 1) {
                  matched = false;
                  break;
                }
              }
              else if (abs(val.first) == 321) {
                if (val.second != 1) {
                  matched = false;
                  break;
                }
              }
              else if (val.second != 0) {
                matched = false;
                break;
              }
            }
            if (matched) {
              if (p.pid() == 113)
                _sigma[6]->fill(_sqs);
              else if (p.pid() == 221 && _sqs == "3.773"s)
                _sigma[1]->fill(_sqs);
            }
          }
        }
        // rho+/-
        else if (p.abspid() == 213) {
          if (ncount == 2) {
            int sign = p.pid() > 0 ? -1 : 1;
            matched = true;
            for (const auto& val : nRes) {
              if (abs(val.first) == 310) {
                if (val.second != 1) {
                  matched = false;
                  break;
                }
              }
              else if (val.first == 321 * sign) {
                if (val.second != 1) {
                  matched = false;
                  break;
                }
              }
              else if (val.second != 0) {
                matched = false;
                break;
              }
            }
            if (matched) _sigma[5]->fill(_sqs);
          }
        }
        if (matched) break;
      }
    }


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

    /// @}


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


  RIVET_DECLARE_PLUGIN(BESII_2009_I835937);

}

Rivet analyses

Cross sections for e+e− → KS0K−K−K+π+, KS0K−π+η, KS0K−ρ+, KS0K−π+ρ0 at 3.65 and 3.773 GeV

Source code:BESII_2009_I835937.cc

Cross sections for e⁺e⁻ → K_S⁰K⁻K⁻K⁺π⁺, K_S⁰K⁻π⁺η, K_S⁰K⁻ρ⁺, K_S⁰K⁻π⁺ρ⁰ at 3.65 and 3.773 GeV

Source code:`BESII_2009_I835937.cc`