Rivet analyses

title: TASSO_1982_I177174

Charged Particle spectra in $e^+e^-$ collisions in $e^+e^-$ at 12, 14, 22, 25, 30, 34 and 35 GeV

Experiment: TASSO (Petra)

Inspire ID: 177174

Status: VALIDATED

Authors: - Peter Richardson

References: - Phys.Lett. 114B (1982) 65

Beams: e+ e-

Beam energies: (6.0, 6.0); (7.0, 7.0); (11.0, 11.0); (12.5, 12.5); (15.0, 15.0); (17.0, 17.0); (17.5, 17.5)GeV

Run details: - e+ e- to hadrons.

Measurement of the charged particle spectra in $e^+e^-$ collisions in $e^+e^-$ at 12, 14, 22, 25, 30, 34 and 35 GeV by the TASSO experiment at Petra.

Source code:TASSO_1982_I177174.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/Beam.hh"

include "Rivet/Projections/ChargedFinalState.hh"

namespace Rivet {

/// @brief Charged particle spectra for a range of energies class TASSO_1982_I177174 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(TASSO_1982_I177174);


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

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

  size_t ih = 1;
  for (double eVal : allowedEnergies()) {
    const string en = toString(round(eVal));
    if (isCompatibleWithSqrtS(eVal)) _sqs = en;
    book(_h[en + "x2"], 2, 1, ih);
    book(_h[en + "x3"], 3, 1, ih);
    if (en == "14"s || en == "22"s) {
      book(_h[en + "x1"], 1, 1, ih - 1);
    }
    else if (en == "30"s) {
      book(_h["x1"], 1, 1, 3);
    }
    ++ih;
  }
  raiseBeamErrorIf(_sqs.empty());
}


/// Perform the per-event analysis
void analyze(const Event& event) {
  // First, veto on leptonic events by requiring at least 4 charged FS particles
  const ChargedFinalState& fs = apply<ChargedFinalState>(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) vetoEvent;

  // Get beams and average beam momentum
  const ParticlePair& beams = apply<Beam>(event, "Beams").beams();
  const double meanBeamMom = 0.5 * (beams.first.p3().mod() + beams.second.p3().mod());
  MSG_DEBUG("Avg beam momentum = " << meanBeamMom);

  for (const Particle& p : fs.particles()) {
    double xp = p.p3().mod() / meanBeamMom;
    if (_sqs == "14"s || _sqs == "22"s)
      _h[_sqs + "x1"]->fill(xp);
    else if (sqrtS() > 29 * GeV)
      _h["x1"]->fill(xp);
    _h[_sqs + "x2"]->fill(xp);
    _h[_sqs + "x3"]->fill(xp);
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  for (auto& item : _h) {
    if (item.first.find("x3") != string::npos) {
      scale(item.second, 1.0 / sumOfWeights());
    }
    else {
      // The sqrtS-dependence is not reentrant safe
      scale(item.second, crossSection() / microbarn / sumOfWeights() * sqr(sqrtS()));
    }
  }
}

/// @}


/// @name Histograms
/// @{
map<string, Histo1DPtr> _h;
string _sqs = "";
/// @}

};

RIVET_DECLARE_PLUGIN(TASSO_1982_I177174); } ```