Rivet analyses

title: BESII_2004_I622224

Charged particle momentum distributions for energies between 2.2 and 4.8 GeV

Experiment: BESII (BEPC)

Inspire ID: 622224

Status: VALIDATED

Authors: - Peter Richardson

References: - Phys.Rev. D69 (2004) 072002, 2004

Beams: e+ e-

Beam energies: (1.1, 1.1); (1.3, 1.3); (1.5, 1.5); (1.6, 1.6); (2.3, 2.3); (2.4, 2.4)GeV

Run details: - e+e- to hadrons.

Charged particle momentum distributions for energies between 2.2 and 4.8 GeV.

Source code:BESII_2004_I622224.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/ChargedFinalState.hh"

namespace Rivet {

/// @brief Charged particle spectra between 2.2 and 4.8 GeV class BESII_2004_I622224 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BESII_2004_I622224);


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

/// Book histograms and initialise projections before the run
void init() {
  const ChargedFinalState fs;
  declare(fs, "FS");

  size_t ih = 0;
  for (double eVal : allowedEnergies()) {
    ++ih;
    const string en = toString(round(eVal / MeV));
    if (isCompatibleWithSqrtS(eVal, 1e-3)) _sqs = en;
    book(_h[en], ih, 1, 1);
    book(_c[en], "TMP/Weight_" + en);
  }
  raiseBeamErrorIf(_sqs.empty());
}

string map2string(const double xi) const {
  const size_t idx = axis.index(xi) - 1;
  if (idx < edges.size()) return edges[idx];
  return "OTHER";
}

/// Perform the per-event analysis
void analyze(const Event& event) {
  if (edges.empty()) edges = _h[_sqs]->xEdges();
  const ChargedFinalState& fs = apply<ChargedFinalState>(event, "FS");
  if (fs.particles().size() == 2 && abs(fs.particles()[0].pid()) == 13
      && abs(fs.particles()[1].pid()) == 13)
    vetoEvent;
  for (const Particle& p : fs.particles()) {
    const Vector3 mom3 = p.p3();
    double pp = mom3.mod();
    double xi = -log(2. * pp / sqrtS());
    _h[_sqs]->fill(map2string(xi));
  }
  _c[_sqs]->fill();
}


/// Normalise histograms etc., after the run
void finalize() {
  for (auto& item : _h) {
    scale(item.second, 1. / dbl(*_c[item.first]));
    for (auto& b : item.second->bins()) {
      const size_t idx = b.index();
      b.scaleW(1. / axis.width(idx));
    }
  }
}

/// @}


/// @name Histograms
/// @{
map<string, BinnedHistoPtr<string>> _h;
map<string, CounterPtr> _c;
vector<string> edges;
string _sqs = "";
YODA::Axis<double> axis{0.05, 0.45, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7,
                        1.8,  1.9,  2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.5};
/// @}

};

RIVET_DECLARE_PLUGIN(BESII_2004_I622224);

} ```