Rivet analyses

Cross section for e+e− → π+π−π0 near the ϕ mass

Experiment: CMD2 (VEPP-2M)

Inspire ID: 480170

Status: VALIDATED

Authors: - Peter Richardson

References: - Phys.Lett. B434 (1998) 426-436, 1998

Beams: e+ e-

Beam energies: ANY

Run details: - e+ e- to hadrons

Measurement of the cross section for e+e− → π+π−π0 for energies near the ϕ mass.

Source code:CMD2_1998_I480170.cc

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

namespace Rivet {


  /// @brief Add a short analysis description here
  class CMD2_1998_I480170 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(CMD2_1998_I480170);


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

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

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

      book(_num3pi, "TMP/num3");
    }


    /// 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!=3) vetoEvent;
      if(nCount[-211]==1&&nCount[211]==1&&nCount[111]==1)
    _num3pi->fill();
    }


    /// Normalise histograms etc., after the run
    void finalize() {

      double sigma = _num3pi->val();
      double error = _num3pi->err();
      sigma *= crossSection()/ sumOfWeights() /nanobarn;
      error *= crossSection()/ sumOfWeights() /nanobarn;
      Estimate1DPtr mult;
      book(mult, 1, 1, 1);
      for (auto& b : mult->bins()) {
        if (inRange(sqrtS()/MeV, b.xMin(), b.xMax())) {
          b.set(sigma, error);
        }
      }
    }

    /// @}


    /// @name Histograms
    /// @{
    CounterPtr _num3pi;
    /// @}


  };


  RIVET_DECLARE_PLUGIN(CMD2_1998_I480170);


}