Rivet analyses

title: GAMMAGAMMA_1981_I158474

Multi pion cross sections for energies between 1.44 and 2.15 GeV

Experiment: GAMMAGAMMA (ADONE)

Inspire ID: 158474

Status: VALIDATED

Authors: - Peter Richardson

References: - Nucl.Phys. B184 (1981) 31-39, 1981

Beams: e+ e-

Beam energies: ANY

Run details: - e+e- to hadrons

Measurement of the cross section for $e^+e^-\to$pions for energies between 1.44 and 2.15 GeV

Source code:GAMMAGAMMA_1981_I158474.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/FinalState.hh"

namespace Rivet {

/// @brief e+e- > hadrons class GAMMAGAMMA_1981_I158474 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(GAMMAGAMMA_1981_I158474);


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

/// Book histograms and initialise projections before the run
void init() {
  // Initialise and register projections
  declare(FinalState(), "FS");
  for (unsigned int ix = 0; ix < 6; ++ix)
    book(_h[ix], "TMP/h_" + toString(ix + 1), refData(1, 1, 1 + ix));
  for (unsigned int ix = 6; ix < 9; ++ix) book(_h[ix], "TMP/h_" + toString(ix + 1), refData(2, 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;
  }
  // mu+mu- + photons
  if (nCount[-13] == 1 and nCount[13] == 1 && ntotal == 2 + nCount[22])
    _h[8]->fill(sqrtS());
  else {
    if (ntotal == 3 && nCount[211] == 1 && nCount[-211] == 1 && nCount[111] == 1) {
      _h[0]->fill(sqrtS());
    }
    if (ntotal == 4 && nCount[211] == 1 && nCount[-211] == 1 && nCount[111] == 2) {
      _h[1]->fill(sqrtS());
    }
    if (ntotal == 5 && nCount[211] == 2 && nCount[-211] == 2 && nCount[111] == 1) {
      _h[2]->fill(sqrtS());
    }
    if (ntotal == 6 && nCount[211] == 2 && nCount[-211] == 2 && nCount[111] == 2) {
      _h[3]->fill(sqrtS());
    }
    if (nCount[211] == 1 && nCount[-211] == 1 && ntotal == 2 + nCount[111]) {
      _h[6]->fill(sqrtS());
    }
    if (nCount[211] == 2 && nCount[-211] == 2 && ntotal == 4 + nCount[111]) {
      _h[7]->fill(sqrtS());
    }
    if ((nCount[211] + nCount[-211] + nCount[111]) == ntotal) {
      if (ntotal == 3 || ntotal == 5)
        _h[4]->fill(sqrtS());
      else if (ntotal == 4 || ntotal == 6)
        _h[5]->fill(sqrtS());
    }
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  double fact = crossSection() / sumOfWeights() / nanobarn;
  for (unsigned int ix = 0; ix < 9; ++ix) {
    scale(_h[ix], fact);
    if (ix >= 6) continue;
    Estimate1DPtr tmp;
    book(tmp, 1, 1, 1 + ix);
    barchart(_h[ix], tmp);
  }
  Estimate1DPtr tmp;
  book(tmp, 2, 1, 1);
  divide(_h[6], _h[8], tmp);
  book(tmp, 2, 1, 2);
  divide(_h[7], _h[8], tmp);
}

/// @}


/// @name Histograms
/// @{
Histo1DPtr _h[9];
/// @}

};

RIVET_DECLARE_PLUGIN(GAMMAGAMMA_1981_I158474);

} ```