Rivet analyses

title: TOPAZ_1995_I381900

Charged hadron spectra at 58 GeV

Experiment: TOPAZ (Tristan)

Inspire ID: 381900

Status: VALIDATED

Authors: - Peter Richardson

References: - Phys.Lett. B347 (1995) 171-178, 1995

Beams: e- e+

Beam energies: (29.0, 29.0)GeV

Run details: - e+ e- to hadrons

Measurement of the spectra for charged hadrons in $e^+e^-$ collisions at 58 GeV by the TOPAZ experiment at Tristan. The spectra for all charged hadrons, $\pi^\pm$, $K^\pm$ and $p,\bar{p}$ are included. The spectrum for $K^0,\bar{K}^0$ is also included

Source code:TOPAZ_1995_I381900.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/Beam.hh"

include "Rivet/Projections/ChargedFinalState.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief Add a short analysis description here class TOPAZ_1995_I381900 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(TOPAZ_1995_I381900);


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

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

  // Initialise and register projections
  declare(Beam(), "Beams");
  declare(UnstableParticles(), "UFS");
  const ChargedFinalState cfs;
  declare(cfs, "CFS");

  // Book histograms
  book(_h["charged"], 1, 1, 1);
  book(_h["pi"], 2, 1, 1);
  book(_h["Kp"], 2, 1, 2);
  book(_h["proton"], 2, 1, 3);
  book(_h["K0"], 3, 1, 1);
  book(_wSum, "TMP/wSum");

  _axes["charged"] = YODA::Axis<double>(22, 0.6, 5.0);
  _axes["pi"] = YODA::Axis<double>{1.17, 1.47, 1.77, 2.07,  2.37, 2.545, 2.695, 2.85, 3.1, 3.315,
                                   3.46, 3.56, 3.69, 3.865, 4.05, 4.28,  4.565, 4.77, 4.89};
  _axes["K0"] = YODA::Axis<double>{1.5, 2.1, 2.4, 2.7, 3.0, 3.3, 3.6, 4.5};
}


/// Perform the per-event analysis
void analyze(const Event& event) {
  if (_edges.empty()) {
    for (const auto& item : _h) {
      _edges[item.first] = item.second->xEdges();
    }
  }
  const ChargedFinalState& cfs = apply<ChargedFinalState>(event, "CFS");
  int nch = cfs.particles().size();
  if (nch < 5) vetoEvent;
  // Get beams and average beam momentum
  const ParticlePair& beams = apply<Beam>(event, "Beams").beams();
  const double meanBeamMom = (beams.first.p3().mod() + beams.second.p3().mod()) / 2.0;
  MSG_DEBUG("Avg beam momentum = " << meanBeamMom);
  _wSum->fill();

  // neutral kaons
  const UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");
  for (const Particle& p : ufs.particles(Cuts::pid == 130 || Cuts::pid == 310)) {
    const double xi = -log(p.p3().mod() / meanBeamMom);
    fillhist("K0", "K0", xi);
  }
  // charged particles
  for (const Particle& p : cfs.particles()) {
    double xi = -log(p.p3().mod() / meanBeamMom);
    fillhist("charged", "charged", xi);
    int id = abs(p.pid());
    if (id == 211) {
      fillhist("pi", "pi", xi);
    }
    else if (id == 321) {
      fillhist("Kp", "pi", xi);
    }
    else if (id == 2212) {
      fillhist("proton", "pi", xi);
    }
  }
}

void fillhist(const string& label_hist, const string& label_axis, const double value) {
  string edge = "OTHER";
  size_t idx = _axes[label_axis].index(value);
  // binning for pi, Kp and proton same but different masked bins (pion only 1 masked bin 9)
  if (label_axis == "pi") {
    if (idx == 9)
      idx = 0;
    else if (idx > 9)
      --idx;
  }
  if (idx && idx <= _edges[label_axis].size()) edge = _edges[label_axis][idx - 1];
  _h[label_hist]->fill(edge);
}


/// Normalise histograms etc., after the run
void finalize() {
  scale(_h, 1. / *_wSum);
  for (auto& hist : _h) {
    for (auto& b : hist.second->bins()) {
      size_t idx = b.index();
      if (hist.first == "pi" || _axes.find(hist.first) == _axes.end()) {
        auto it = std::find(_edges["pi"].begin(), _edges["pi"].end(), _edges[hist.first][idx - 1]);
        idx = std::distance(_edges["pi"].begin(), it) + 1;
        if (idx >= 9) ++idx;
        b.scaleW(1. / _axes["pi"].width(idx));
      }
      else
        b.scaleW(1. / _axes[hist.first].width(idx));
    }
  }
}

/// @}


/// @name Histograms
/// @{
CounterPtr _wSum;
map<string, BinnedHistoPtr<string>> _h;
map<string, YODA::Axis<double>> _axes;
map<string, vector<string>> _edges;
/// @}

};

RIVET_DECLARE_PLUGIN(TOPAZ_1995_I381900);

} ```