Rivet analyses

title: DELPHI_1995_I377487

Spectrum for $K^0,\bar{K}^0$ and $K^{*\pm}$ production in hadronic $Z^0$ decays

Experiment: DELPHI (LEP)

Inspire ID: 377487

Status: VALIDATED

Authors: - Peter Richardson

References: - Z.Phys. C65 (1995) 587-602

Beams: e+ e-

Beam energies: (45.6, 45.6)GeV

Run details: - Hadronic Z decay events generated on the Z pole ($\sqrt{s} = 91.2$ GeV)

DELPHI results for the spectra for $K^0,\bar{K}^0$ and $K^{*\pm}$ production in hadronic $Z^0$ decays. The other spectra in the paper are superseded by those in DELPHI_1999_S3960137 and are therefore not implemented.

Source code:DELPHI_1995_I377487.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/Beam.hh"

include "Rivet/Projections/ChargedFinalState.hh"

include "Rivet/Projections/FinalState.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief kaon spectra at LEP1 class DELPHI_1995_I377487 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(DELPHI_1995_I377487);


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

/// Book histograms and initialise projections before the run
void init() {
  declare(Beam(), "Beams");
  declare(ChargedFinalState(), "FS");
  declare(UnstableParticles(), "UFS");

  // Book histograms
  book(_h_K0_x, 8, 1, 1);
  book(_h_K0_xi, 9, 1, 1);
  book(_h_Ks_x, 10, 1, 1);
}


/// Perform the per-event analysis
void analyze(const Event& event) {

  if (_edges.empty()) _edges = _h_K0_x->xEdges();

  // First, veto on leptonic events by requiring at least 4 charged FS particles
  const FinalState& fs = apply<FinalState>(event, "FS");
  const size_t numParticles = fs.particles().size();

  // Even if we only generate hadronic events, we still need a cut on numCharged >= 2.
  if (numParticles < 2) {
    MSG_DEBUG("Failed leptonic event cut");
    vetoEvent;
  }
  MSG_DEBUG("Passed leptonic event cut");

  // 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);

  // Final state of unstable particles to get particle spectra
  const UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");

  for (const Particle& p : ufs.particles(Cuts::pid == 130 or Cuts::pid == 310 or Cuts::abspid == 323)) {
    const double xp = p.p3().mod() / meanBeamMom;
    if (abs(p.pid()) == 323) {
      _h_Ks_x->fill(xp);
    }
    else {
      _h_K0_x->fill(map2string(xp));
      _h_K0_xi->fill(-log(xp));
    }
  }
}

string map2string(const double val) const {
  const size_t idx = _axis.index(val);
  if (idx && idx <= _edges.size()) return _edges[idx - 1];
  return "OTHER";
}


/// Normalise histograms etc., after the run
void finalize() {

  scale(_h_K0_x, 1. / sumOfWeights());
  for (auto& b : _h_K0_x->bins()) {
    const size_t idx = b.index();
    b.scaleW(1. / _axis.width(idx));
  }
  scale(_h_K0_xi, 1. / sumOfWeights());
  scale(_h_Ks_x, 1. / sumOfWeights());
}

/// @}


/// @name Histograms
/// @{
BinnedHistoPtr<string> _h_K0_x;
Histo1DPtr _h_K0_xi, _h_Ks_x;
vector<string> _edges;
YODA::Axis<double> _axis{0.00030213628351706805, 0.00048341905738733416, 0.00048343557923922857,
                         0.00026205300091453314, 0.0007702529509799692,  0.0009481642553664134,
                         0.0017226600969315643,  0.002004423179522298,   0.0016843611112658217,
                         0.0026292281438344,     0.00267627755270744,    0.0036267300396739185,
                         0.004237796021633787,   0.005212931632136056,   0.007189937374782032,
                         0.007726421785666127,   0.010282046710587495,   0.012196841637666128,
                         0.014664716763387292,   0.018701111778413465,   0.02210348200534462,
                         0.027403036058393532,   0.03380578808779788,    0.04112055882855764,
                         0.049671035882778436,   0.22518836390597363,    1.0};
/// @}

};

RIVET_DECLARE_PLUGIN(DELPHI_1995_I377487);

} ```