Rivet analyses

title: KLOE_2007_I725483

$e^+e^-\to\pi^0\pi^0\gamma$

Experiment: KLOE ()

Inspire ID: 725483

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Eur.Phys.J.C 49 (2007) 473-488

Beams: e+ e-

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

Run details: - e+e- > pi0 pi0 gamma, pi0 should be set stable

Measurement of the $\pi^0\pi^0$ and $\pi^0\gamma$ mass distribution in $e^+e^-\to\pi^0\pi^0\gamma$ at centre-of-mass energies near the mass of the phi resonance.

Source code:KLOE_2007_I725483.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/FinalState.hh"

namespace Rivet {

/// @brief e+e- > pi0 pi0 gamma class KLOE_2007_I725483 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(KLOE_2007_I725483);


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

/// Book histograms and initialise projections before the run
void init() {
  // Initialise and register projections
  declare(FinalState(), "FS");
  // get the CMS point
  size_t ih = 1;
  for (double eVal : allowedEnergies()) {
    const string en = toString(round(10 * eVal / MeV));
    if (isCompatibleWithSqrtS(eVal)) _sqs = en;
    book(_h[en + "0"s], 1, ih, 1);
    book(_h[en + "1"s], 1, ih, 2);
    ++ih;
  }
  raiseBeamErrorIf(_sqs.empty());
}


/// Perform the per-event analysis
void analyze(const Event& event) {
  const FinalState& fs = apply<FinalState>(event, "FS");
  Particles pi0, gamma;
  map<long, Particles> nCount;
  int ntotal(0);
  for (const Particle& p : fs.particles()) {
    if (p.pid() == PID::PI0)
      pi0 += p;
    else if (p.pid() == PID::GAMMA)
      gamma += p;
    ++ntotal;
  }
  // three particles (pi0 pi0 gamma)
  if (ntotal != 3 || pi0.size() != 2 || gamma.size() != 1) vetoEvent;
  _h[_sqs + "0"]->fill((pi0[0].mom() + pi0[1].mom()).mass() / MeV);
  _h[_sqs + "1"]->fill((pi0[0].mom() + gamma[0].mom()).mass() / MeV);
  _h[_sqs + "1"]->fill((pi0[1].mom() + gamma[0].mom()).mass() / MeV);
}


/// Normalise histograms etc., after the run
void finalize() {
  normalize(_h);
}

/// @}


/// @name Histograms
/// @{
map<string, Histo1DPtr> _h;
string _sqs = "";
/// @}

};

RIVET_DECLARE_PLUGIN(KLOE_2007_I725483);

} ```