Rivet analyses

title: SND_2001_I533574

Cross section for $e^+e^-\to$ $K^+K^-$, $K_S^0K_L^0$ and $\pi^+\pi^-\pi^0$ near the $\phi$ resonance

Experiment: SND (VEPP-2M)

Inspire ID: 533574

Status: VALIDATED

Authors: - Peter Richardson

References: - Phys.Rev. D63 (2001) 072002

Beams: e+ e-

Beam energies: ANY

Run details: - e+e- to hadrons

Measurement of the cross section for $e^+e^-\to$ $K^+K^-$, $K_S^0K_L^0$ and $\pi^+\pi^-\pi^0$ near the $\phi$ resonance

Source code:SND_2001_I533574.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/FinalState.hh"

namespace Rivet {

/// @brief e+ e- > K+K-, KS0 KL0 and pi+pi-pi0 class SND_2001_I533574 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(SND_2001_I533574);


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

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

  // Initialise and register projections
  declare(FinalState(), "FS");
  for (size_t ix = 0; ix < 2; ++ix) {
    for (size_t iy = 0; iy < 4; ++iy) {
      book(_sigma[ix][iy], 1 + ix, 1, 1 + iy);
    }
    for (const string& en : _sigma[ix][3].binning().edges<0>()) {
      double eval = stod(en) * MeV;
      if (isCompatibleWithSqrtS(eval)) {
        _sqs[ix] = en;
        break;
      }
    }
  }
  raiseBeamErrorIf(_sqs[0].empty() && _sqs[1].empty());
}


/// 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 == 2) {
    if (nCount[321] == 1 && nCount[-321] == 1) {
      _sigma[0][0]->fill(_sqs[0]);
      _sigma[1][0]->fill(_sqs[1]);
    }
    else if (nCount[130] == 1 && nCount[310] == 1) {
      _sigma[0][1]->fill(_sqs[0]);
      _sigma[0][2]->fill(_sqs[0]);
      _sigma[1][1]->fill(_sqs[1]);
      _sigma[1][2]->fill(_sqs[1]);
    }
  }
  else if (ntotal == 3 && nCount[211] == 1 && nCount[-211] == 1 && nCount[111] == 1) {
    _sigma[0][3]->fill(_sqs[0]);
    _sigma[1][3]->fill(_sqs[1]);
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  const double fact = crossSection() / sumOfWeights() / nanobarn;
  scale(_sigma[0], fact);
  scale(_sigma[1], fact);
}

/// @}


/// @name Histograms
/// @{
BinnedHistoPtr<string> _sigma[2][4];
string _sqs[2];
/// @}

};

RIVET_DECLARE_PLUGIN(SND_2001_I533574); } ```