Rivet analyses

e+e− → π+π−π0π0 cross section from 0.85 to 4.5 GeV

Experiment: BABAR (PEP-II)

Inspire ID: 1621593

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Phys.Rev. D96 (2017) no.9, 092009

Beams: e+ e-

Beam energies: ANY

Run details: - e+ e- to hadrons

Measurement of the cross section for e+e− → π+π−π0π0 between 0.85 to 4.5 GeV using radiative return.

Source code:BABAR_2017_I1621593.cc

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


namespace Rivet {


  /// @brief e+e- > pi+ pi- 2pi0 (including omega)
  class BABAR_2017_I1621593 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(BABAR_2017_I1621593);


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

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

      // Initialise and register projections
      declare(FinalState(), "FS");
      declare(UnstableParticles(), "UFS");
      for (unsigned int ix = 0; ix < 2; ++ix)
        book(_mult[ix], "TMP/mult_" + toString(ix), refData(1 + ix, 1, 1));
    }


    /// 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 != 4) vetoEvent;
      if (nCount[-211] == 1 && nCount[211] == 1 && nCount[111] == 2) {
        _mult[0]->fill(sqrtS() / GeV);
        const FinalState& ufs = apply<FinalState>(event, "UFS");
        if (!ufs.particles(Cuts::pid == 223).empty()) {
          _mult[1]->fill(sqrtS() / GeV);
        }
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      double fact = crossSection() / sumOfWeights() / nanobarn;
      for (size_t ix = 0; ix < 2; ++ix) {
        scale(_mult[ix], fact);
        Estimate1DPtr tmp;
        book(tmp, 1 + ix, 1, 1);
        barchart(_mult[ix], tmp);
      }
    }

    /// @}

    /// @name Histograms
    /// @{
    Histo1DPtr _mult[2];
    /// @}
  };


  RIVET_DECLARE_PLUGIN(BABAR_2017_I1621593);


}