Rivet analyses

title: TASSO_1983_I181470

$\pi^\pm$, $K^\pm$ and $p,\bar{p}$ spectra in $e^+e^-$ at 14, 22 and 34 GeV

Experiment: TASSO (Petra)

Inspire ID: 181470

Status: VALIDATED

Authors: - Peter Richardson

References: - Z.Phys. C17 (1983) 5-15, 1983

Beams: e+ e-

Beam energies: (7.0, 7.0); (11.0, 11.0); (17.0, 17.0)GeV

Run details: - e+ e- to hadrons.

Measurement of the $\pi^\pm$, $K^\pm$ and $p,\bar{p}$ spectra in $e^+e^-$ collisions for centre-of-mass energies of 14, 22 and 34 GeV by the TASSO experiment at Petra.

Source code:TASSO_1983_I181470.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/Beam.hh"

include "Rivet/Projections/FinalState.hh"

namespace Rivet {

/// @brief pi, K and proton spectra at 14,22 and 34 GeV class TASSO_1983_I181470 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(TASSO_1983_I181470);


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

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

  // Initialise and register projections
  declare(Beam(), "Beams");
  declare(FinalState(), "FS");

  for (double eVal : allowedEnergies()) {
    const string en = toString(round(eVal));
    if (isCompatibleWithSqrtS(eVal)) _sqs = en;
    size_t ih1 = 0, ih2 = 0;
    if (en == "14"s) {
      ih1 = 19;
      ih2 = 22;
    }
    if (en == "22"s) {
      ih1 = 25;
      ih2 = 10;
    }
    if (en == "34"s) {
      ih1 = 13;
      ih2 = 16;
    }
    book(_h[en + "p_pi"], ih1, 1, 1);
    book(_h[en + "p_K"], ih1 + 2, 1, 1);
    book(_h[en + "p_p"], ih2 + 1, 1, 1);
    book(_h[en + "x_pi"], ih1 + 1, 1, 1);
    book(_h[en + "x_K"], ih2, 1, 1);
    book(_h[en + "x_p"], ih2 + 2, 1, 1);
  }
  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 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) 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 xE = p.E() / meanBeamMom;
    if (p.abspid() == 211) {
      _h[_sqs + "p_pi"]->fill(p.p3().mod());
      _h[_sqs + "x_pi"]->fill(xE);
    }
    else if (p.abspid() == 321) {
      _h[_sqs + "p_K"]->fill(p.p3().mod());
      _h[_sqs + "x_K"]->fill(xE);
    }
    else if (p.abspid() == 2212) {
      _h[_sqs + "p_p"]->fill(p.p3().mod());
      _h[_sqs + "x_p"]->fill(xE);
    }
  }
}


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

  for (auto& item : _h) {
    if (item.first.find("p_") != string::npos) {
      scale(item.second, crossSection() / nanobarn / sumOfWeights());
    }
    else {
      const double en = stod(item.first.substr(0, 2));
      scale(item.second, sqr(en) / GeV2 * crossSection() / microbarn / sumOfWeights());
    }
  }
}

/// @}


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

};

RIVET_DECLARE_PLUGIN(TASSO_1983_I181470); } ```