Rivet analyses

title: CMD2_1998_I480170

Cross section for $e^+e^-\to \pi^+\pi^-\pi^0$ near the $\phi$ 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 $e^+e^-\to \pi^+\pi^-\pi^0$ for energies near the $\phi$ mass.

Source code:CMD2_1998_I480170.cc

```c++ // -- 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);

} ```