Rivet analyses

title: TASSO_1989_I267755

$\pi^\pm$, $K^\pm$ and $p,\bar{p}$ spectra in $e^+e^-$ at 34 and 44 GeV

Experiment: TASSO (Petra)

Inspire ID: 267755

Status: VALIDATED

Authors: - Peter Richardson

References: - Z.Phys. C42 (1989) 189, 1989

Beams: e+ e-

Beam energies: (17.0, 17.0); (22.0, 22.0)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 34 and 44 GeV by the TASSO experiment at Petra.

Source code:TASSO_1989_I267755.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/Beam.hh"

include "Rivet/Projections/ChargedFinalState.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief pi, K and p spectra at 34 and 44 GeV class TASSO_1989_I267755 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(TASSO_1989_I267755);


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

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

  // Initialise and register projections
  declare(Beam(), "Beams");
  declare(ChargedFinalState(), "FS");
  declare(UnstableParticles(), "UFS");

  // Book histograms
  size_t ih = 0;
  for (double eVal : allowedEnergies()) {
    const string en = toString(round(eVal));
    if (isCompatibleWithSqrtS(eVal)) _sqs = en;
    book(_c[en], "_sumW_" + en);
    book(_h[en + "x_pi"], 3 * ih + 7, 1, 1);
    book(_h[en + "x_K"], 3 * ih + 8, 1, 1);
    book(_h[en + "x_p"], 3 * ih + 9, 1, 1);
    if (en == "44"s) book(_h[en + "x_pi0"], 13, 1, 1);
    book(_h[en + "n_pi"], "TMP/n_pi" + en, refData(3 * ih + 1, 1, 1));
    book(_h[en + "d_pi"], "TMP/d_pi" + en, refData(3 * ih + 1, 1, 1));
    book(_h[en + "n_K"], "TMP/n_K" + en, refData(3 * ih + 2, 1, 1));
    book(_h[en + "d_K"], "TMP/d_K" + en, refData(3 * ih + 2, 1, 1));
    book(_h[en + "n_p"], "TMP/n_p" + en, refData(3 * ih + 3, 1, 1));
    book(_h[en + "d_p"], "TMP/d_p" + en, refData(3 * ih + 3, 1, 1));
    ++ih;
  }
  raiseBeamErrorIf(_sqs.empty());
}


/// Perform the per-event analysis
void analyze(const Event& event) {
  _c[_sqs]->fill();
  // 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;
    _h[_sqs + "d_pi"]->fill(xP);
    _h[_sqs + "d_K"]->fill(xP);
    _h[_sqs + "d_p"]->fill(xP);
    if (p.abspid() == 211) {
      _h[_sqs + "x_pi"]->fill(xP);
      _h[_sqs + "n_pi"]->fill(xP);
    }
    else if (p.abspid() == 321) {
      _h[_sqs + "x_K"]->fill(xP);
      _h[_sqs + "n_K"]->fill(xP);
    }
    else if (p.abspid() == 2212) {
      _h[_sqs + "x_p"]->fill(xP);
      _h[_sqs + "n_p"]->fill(xP);
    }
  }
  if (_sqs == "44"s) {
    for (const Particle& p : apply<UnstableParticles>(event, "UFS").particles(Cuts::pid == 111)) {
      _h[_sqs + "x_pi0"]->fill(p.p3().mod() / meanBeamMom);
    }
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  scale(_c, crossSectionPerEvent());
  scale(_h, crossSectionPerEvent());
  for (auto& item : _h) {
    const double w = _c[item.first.substr(0, 2)]->sumW();
    if (!isZero(w)) scale(item.second, 1.0 / w);
  }
  size_t ih = 0;
  Estimate1DPtr temp;
  for (double eVal : allowedEnergies()) {
    const string en = toString(round(eVal));
    book(temp, 3 * ih + 1, 1, 1);
    divide(_h[en + "n_pi"], _h[en + "d_pi"], temp);
    book(temp, 3 * ih + 2, 1, 1);
    divide(_h[en + "n_K"], _h[en + "d_K"], temp);
    book(temp, 3 * ih + 3, 1, 1);
    divide(_h[en + "n_p"], _h[en + "d_p"], temp);
    ++ih;
  }
}

/// @}


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

};

RIVET_DECLARE_PLUGIN(TASSO_1989_I267755); } ```