Rivet analyses

title: TASSO_1985_I205119

$K^0,\bar{K}^0$ and $\Lambda^0,\bar{\Lambda}^0$ spectra at 14, 22 and 34 GeV

Experiment: TASSO (Petra)

Inspire ID: 205119

Status: VALIDATED

Authors: - Peter Richardson

References: - Z.Phys. C27 (1985) 27, 1985

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 $K^0,\bar{K}^0$ and $\Lambda^0,\bar{\Lambda}^0$ 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_1985_I205119.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/Beam.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief K0 and Lambda spectra at 14, 22 and 34 GeV. class TASSO_1985_I205119 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(TASSO_1985_I205119);


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

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

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

  // Book histograms
  size_t ih = 0;
  for (double eVal : allowedEnergies()) {
    const string en = toString(round(eVal / MeV));
    if (isCompatibleWithSqrtS(eVal)) _sqs = en;
    book(_h[en + "kaon_x"], 1 + ih, 1, 1);
    book(_h[en + "lambda_x"], 4 + ih, 1, 1);
    book(_h[en + "kaon_p"], 7 + ih, 1, 1);
    book(_h[en + "lambda_p"], 10 + ih, 1, 1);
    ++ih;
  }
  raiseBeamErrorIf(_sqs.empty());
}


/// Perform the per-event analysis
void analyze(const Event& event) {
  // 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 :
       apply<UnstableParticles>(event, "UFS")
           .particles(Cuts::abspid == PID::LAMBDA || Cuts::pid == 130 || Cuts::pid == 310)) {
    const double xE = p.E() / meanBeamMom;
    const double modp = p.p3().mod();
    const double beta = modp / p.E();
    if (p.abspid() == PID::LAMBDA) {
      _h[_sqs + "lambda_x"]->fill(xE, 1. / beta);
      _h[_sqs + "lambda_p"]->fill(modp, 1.);
    }
    else {
      _h[_sqs + "kaon_x"]->fill(xE, 1. / beta);
      _h[_sqs + "kaon_p"]->fill(modp, 1.);
    }
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  for (double eVal : allowedEnergies()) {
    const string en = toString(round(eVal / MeV));
    scale({_h[en + "kaon_x"], _h[en + "lambda_x"]},
          sqr(eVal) * crossSection() / microbarn / sumOfWeights());
    scale({_h[en + "kaon_p"], _h[en + "lambda_p"]}, crossSection() / nanobarn / sumOfWeights());
  }
}

/// @}


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

};

RIVET_DECLARE_PLUGIN(TASSO_1985_I205119); } ```