Rivet analyses

title: KLOE_2008_I791841

Cross section for $\pi^+\pi^-2\pi^0$ and $2\pi^0\gamma$ near the $\phi$ mass

Experiment: KLOE (DAPHNE)

Inspire ID: 791841

Status: VALIDATED

Authors: - Peter Richardson

References: - Phys.Lett. B669 (2008) 223-228, 2008

Beams: e+ e-

Beam energies: (0.5, 0.5); (0.5, 0.5); (0.5, 0.5); (0.5, 0.5); (0.5, 0.5); (0.5, 0.5); (0.5, 0.5); (0.5, 0.5); (0.5, 0.5); (0.5, 0.5); (0.5, 0.5); (0.5, 0.5); (0.5, 0.5); (0.5, 0.5); (0.5, 0.5); (0.5, 0.5); (0.5, 0.5)GeV

Run details: - e+e- to hadrons

Measurement of the cross section for $\pi^+\pi^-2\pi^0$ and $2\pi^0\gamma$ near the $\phi$ mass.

Source code:KLOE_2008_I791841.cc

```c++ // -- C++ --

include "Rivet/Analysis.hh"

include "Rivet/Projections/FinalState.hh"

namespace Rivet {

/// @brief e+e- -> pi+pi-2pi0 and 2pi0gamma near the phi class KLOE_2008_I791841 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(KLOE_2008_I791841);


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

/// Book histograms and initialise projections before the run
void init() {
  // Initialise and register projections
  declare(FinalState(), "FS");
  book(_n4pi, 1, 1, 1);
  book(_n2pigamma, 2, 1, 1);
  for (const string& en : _n4pi.binning().edges<0>()) {
    const double eval = stod(en) * MeV;
    if (isCompatibleWithSqrtS(eval)) {
      _sqs = en;
      break;
    }
  }
  raiseBeamErrorIf(_sqs.empty());
}


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

  map<long, int> nCount;
  for (const Particle& p : fs.particles()) {
    nCount[p.pid()] += 1;
  }
  if (nCount[111] == 2) {
    if (nCount[211] == 1 && nCount[-211] == 1) {
      _n4pi->fill(_sqs);
    }
    else if (nCount[22] == 1) {
      _n2pigamma->fill(_sqs);
    }
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  const double fact = crossSection() / sumOfWeights() / nanobarn;
  scale(_n4pi, fact);
  scale(_n2pigamma, fact);
}

/// @}


/// @name Histograms
/// @{
BinnedHistoPtr<string> _n4pi, _n2pigamma;
string _sqs = "";
/// @}

};

RIVET_DECLARE_PLUGIN(KLOE_2008_I791841);

} ```