Rivet analyses

title: BABAR_2021_I1937349

Cross section for $e^+e^-\to$ $\pi^+\pi^-\pi^0$ between 0.62 and 3.5 GeV

Experiment: BABAR (PEP-II)

Inspire ID: 1937349

Status: VALIDATED

Authors: - Peter Richardson

References: - arXiv: 2110.00520

Beams: e+ e-

Beam energies: ANY

Run details: none listed

Measurement of the cross section for $e^+e^-\to \pi^+\pi^-\pi^0$ by BaBar using radiative return for energies between 0.62 and 3.5 GeV. The contribution of the $J/\psi$ has been subtracted.

Source code:BABAR_2021_I1937349.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/FinalState.hh"

namespace Rivet {

/// @brief e+e- -> pi+pi-pi0 class BABAR_2021_I1937349 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BABAR_2021_I1937349);


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

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

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

  book(_num3pi, "TMP/num3", refData(1, 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 != 3) vetoEvent;
  if (nCount[-211] == 1 && nCount[211] == 1 && nCount[111] == 1) _num3pi->fill(sqrtS());
}


/// Normalise histograms etc., after the run
void finalize() {
  scale(_num3pi, crossSection() / sumOfWeights() / nanobarn);
  Estimate1DPtr tmp;
  book(tmp, 1, 1, 1);
  barchart(_num3pi, tmp);
}

///@}


/// @name Histograms
///@{
Histo1DPtr _num3pi;
///@}

};

RIVET_DECLARE_PLUGIN(BABAR_2021_I1937349);

} ```