Rivet analyses

e+e− → KS0KS0π+π− below 2 GeV

Experiment: CMD3 (VEPP-2M)

Inspire ID: 1770428

Status: VALIDATED

Authors: - Peter Richardson

References: - arXiv: 1912.05751

Beams: e- e+

Beam energies: ANY

Run details: - e+e- to hadrons

Measurement of the cross section for e+e− → KS0KS0π+π− below 2 GeV by the CMD3 experiment

Source code:CMD3_2019_I1770428.cc

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

namespace Rivet {


  /// @brief CMD3 K0 K0 pi+pi-
  class CMD3_2019_I1770428 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(CMD3_2019_I1770428);


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

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

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

      // Book histograms
      book(_cK0K0pippim, "TMP/K0K0pippim", refData(1, 1, 6));
      book(_h_pipi, 2, 1, 1);
      book(_h_total, 2, 1, 2);
    }


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

      map<long, int> nCount;
      int ntotal(0);
      Particles pip, k0;
      for (const Particle& p : fs.particles()) {
        nCount[p.pid()] += 1;
        if (p.abspid() == 211)
          pip.push_back(p);
        else if (p.pid() == 310)
          k0.push_back(p);
        ++ntotal;
      }
      if (ntotal == 4 && nCount[310] == 2 && nCount[211] == 1 && nCount[-211] == 1) {
        _cK0K0pippim->fill(sqrtS() / MeV);
        FourMomentum ppipi = pip[0].momentum() + pip[1].momentum();
        _h_pipi->fill(ppipi.mass() / MeV);
        for (unsigned int ix = 0; ix < 2; ++ix) _h_total->fill((ppipi + k0[ix].momentum()).mass() / MeV);
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      normalize(_h_pipi);
      normalize(_h_total);
      scale(_cK0K0pippim, crossSection() / sumOfWeights() / nanobarn);
      Estimate1DPtr mult;
      book(mult, 1, 1, 6);
      barchart(_cK0K0pippim, mult);
    }

    /// @}


    /// @name Histograms
    /// @{
    Histo1DPtr _cK0K0pippim;
    Histo1DPtr _h_pipi, _h_total;
    /// @}
  };


  RIVET_DECLARE_PLUGIN(CMD3_2019_I1770428);


}