Rivet analyses

title: TPC_1987_I235694

Charged Hadron multiplicity at 29 GeV, flavour separated

Experiment: TPC (PEP)

Inspire ID: 235694

Status: VALIDATED

Authors: - Peter Richardson

References: - Phys.Lett. B184 (1987) 299-304

Beams: e+ e-

Beam energies: (14.5, 14.5)GeV

Run details: - Hadronic e+e- events at $\sqrt{s} = 29.$ GeV

The charged particle multiplicity distribution of hadronic $e^+e^-$ events, as measured at $\sqrt{s} = 29.$ GeV using the TPC detector at PEP. The multiplicities are measured separately for light, charm and bottom events as well as the results averaged over the quark flavours.

Source code:TPC_1987_I235694.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/Beam.hh"

include "Rivet/Projections/ChargedFinalState.hh"

define I_KNOW_THE_INITIAL_QUARKS_PROJECTION_IS_DODGY_BUT_NEED_TO_USE_IT

include "Rivet/Projections/InitialQuarks.hh"

namespace Rivet {

/// @brief TPC flavour separated N charged at 29 GeV class TPC_1987_I235694 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(TPC_1987_I235694);


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

/// Book histograms and initialise projections before the run
void init() {
  // Histograms
  book(_h_all, 5, 1, 4);
  book(_h_light, 4, 1, 4);
  book(_h_charm, 3, 1, 4);
  book(_h_bottom, 2, 1, 4);
  // Projections
  declare(Beam(), "Beams");
  declare(ChargedFinalState(), "CFS");
  declare(InitialQuarks(), "IQF");
}


/// Perform the per-event analysis
void analyze(const Event& event) {
  // Even if we only generate hadronic events, we still need a cut on numCharged >= 2.
  const FinalState& cfs = apply<FinalState>(event, "CFS");
  if (cfs.size() < 2) vetoEvent;


  int flavour = 0;
  const InitialQuarks& iqf = apply<InitialQuarks>(event, "IQF");

  // If we only have two quarks (qqbar), just take the flavour.
  // If we have more than two quarks, look for the highest energetic q-qbar pair.
  if (iqf.particles().size() == 2) {
    flavour = iqf.particles().front().abspid();
  }
  else {
    map<int, double> quarkmap;
    for (const Particle& p : iqf.particles()) {
      if (quarkmap[p.pid()] < p.E()) {
        quarkmap[p.pid()] = p.E();
      }
    }
    double maxenergy = 0.;
    for (int i = 1; i <= 5; ++i) {
      if (quarkmap[i] + quarkmap[-i] > maxenergy) {
        flavour = i;
      }
    }
  }
  const size_t numParticles = cfs.particles().size();
  switch (flavour) {
    case 1:
    case 2:
    case 3: _h_light->fill(29, numParticles); break;
    case 4: _h_charm->fill(29, numParticles); break;
    case 5: _h_bottom->fill(29, numParticles); break;
  }
  _h_all->fill(29, numParticles);
}


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

private:

/// @name Multiplicities
/// @{
BinnedProfilePtr<int> _h_all;
BinnedProfilePtr<int> _h_light;
BinnedProfilePtr<int> _h_charm;
BinnedProfilePtr<int> _h_bottom;
/// @}

};

RIVET_DECLARE_PLUGIN(TPC_1987_I235694);

} ```