Rivet analyses

title: ARGUS_1988_I251097

Hyperon spectra in $e^+e^-$ collisions in the continuum at 10 GeV and at $\Upsilon_{1,2}$

Experiment: ARGUS (DORIS)

Inspire ID: 251097

Status: VALIDATED

Authors: - Peter Richardson

References: - Z.Phys. C39 (1988) 177, 1988

Beams: e- e+

Beam energies: (4.7, 4.7); (5.0, 5.0); (5.0, 5.0)GeV

Run details: - $e^+ e^-$ analysis near the $\Upsilon$ resonances

Measurement of the spectra for the production of $\Lambda$ and $\Xi^-$ baryons. Data are taken on the $\Upsilon(1S)$, $\Upsilon(2S)$ and in the nearby continuum. N.B. data tables 10 onwards are duplicates and therefore not implemented.

Source code:ARGUS_1988_I251097.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief hyperon production class ARGUS_1988_I251097 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(ARGUS_1988_I251097);


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

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

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

  for (unsigned int ix = 0; ix < 2; ++ix) {
    for (unsigned int iy = 0; iy < 7; ++iy) {
      book(_mult[ix][iy], ix + 1, 1, iy + 1);
    }
  }
  book(_hist_ups1_lambda, 3, 1, 1);
  book(_hist_ups2_lambda, 4, 1, 1);
  book(_hist_cont_lambda1, 5, 1, 1);
  book(_hist_cont_lambda2, 6, 1, 1);

  book(_hist_ups1_xi, 7, 1, 1);
  book(_hist_ups2_xi, 8, 1, 1);
  book(_hist_cont_xi, 9, 1, 1);
  book(_weightSum_cont, "TMP/sum_cont");
  book(_weightSum_Ups1, "TMP/sum_ups1");
  book(_weightSum_Ups2, "TMP/sum_ups2");
}

/// Recursively walk the decay tree to find decay products of @a p
void findDecayProducts(Particle mother, Particles& unstable) {
  for (const Particle& p : mother.children()) {
    const int id = abs(p.pid());
    if (id == 3122 || id == 3312 || id == 3212 || id == 3114 || id == 3224 || id == 3324 || id == 3334) {
      unstable.push_back(p);
    }
    if (!p.children().empty()) findDecayProducts(p, unstable);
  }
}

/// Perform the per-event analysis
void analyze(const Event& event) {
  // First in unstable final state
  const UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");
  Particles upsilons = ufs.particles(Cuts::pid == 553 || Cuts::pid == 100553);
  // continuum
  if (upsilons.empty()) {
    _weightSum_cont->fill();
    for (const Particle& p : ufs.particles()) {
      int id = p.abspid();
      double modp = p.p3().mod();
      double xp = 2. * modp / sqrtS();
      double xE = 2. * p.E() / sqrtS();
      double beta = modp / p.E();
      if (id == 3122) {
        _hist_cont_lambda1->fill(xp);
        _hist_cont_lambda2->fill(xE, 1. / beta);
        _mult[1][0]->fill(Ecms);
      }
      else if (id == 3312) {
        _hist_cont_xi->fill(xE, 1. / beta);
        _mult[1][1]->fill(Ecms);
      }
      else if (id == 3212) {
        _mult[1][2]->fill(Ecms);
      }
      else if (id == 3114) {
        _mult[1][3]->fill(Ecms);
      }
      else if (id == 3224) {
        _mult[1][4]->fill(Ecms);
      }
      else if (id == 3324) {
        _mult[1][5]->fill(Ecms);
      }
      else if (id == 3334) {
        _mult[1][6]->fill(Ecms);
      }
    }
  }
  // Upslion decays
  else {
    for (const Particle& ups : upsilons) {
      const int parentId = ups.pid();
      if (parentId == 553)
        _weightSum_Ups1->fill();
      else
        _weightSum_Ups2->fill();
      Particles unstable;
      // Find the decay products we want
      findDecayProducts(ups, unstable);
      LorentzTransform cms_boost;
      if (ups.p3().mod() > 0.001)
        cms_boost = LorentzTransform::mkFrameTransformFromBeta(ups.momentum().betaVec());
      double mass = ups.mass();
      for (const Particle& p : unstable) {
        int id = p.abspid();
        FourMomentum p2 = cms_boost.transform(p.momentum());
        double modp = p2.p3().mod();
        double xp = 2. * modp / mass;
        if (id == 3122) {
          if (parentId == 553) {
            _hist_ups1_lambda->fill(xp);
            _mult[0][0]->fill(Ecms);
          }
          else {
            _hist_ups2_lambda->fill(xp);
          }
        }
        else if (id == 3312) {
          if (parentId == 553) {
            _hist_ups1_xi->fill(xp);
            _mult[0][1]->fill(Ecms);
          }
          else {
            _hist_ups2_xi->fill(xp);
          }
        }
        else if (parentId == 553) {
          if (id == 3212) {
            _mult[0][2]->fill(Ecms);
          }
          else if (id == 3114) {
            _mult[0][3]->fill(Ecms);
          }
          else if (id == 3224) {
            _mult[0][4]->fill(Ecms);
          }
          else if (id == 3324) {
            _mult[0][5]->fill(Ecms);
          }
          else if (id == 3334) {
            _mult[0][6]->fill(Ecms);
          }
        }
      }
    }
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  // multiplicities
  const vector<CounterPtr> scales = {_weightSum_Ups1, _weightSum_cont};
  for (unsigned int ix = 0; ix < 2; ++ix) {
    if (scales[ix]->effNumEntries() <= 0.) continue;
    scale(_mult[ix], 1. / *scales[ix]);
  }
  if (_weightSum_Ups1->val() > 0.) {
    scale(_hist_ups1_lambda, 1. / *_weightSum_Ups1);
    scale(_hist_ups1_xi, 1. / *_weightSum_Ups1);
  }
  if (_weightSum_Ups2->val() > 0.) {
    scale(_hist_ups2_lambda, 1. / *_weightSum_Ups2);
    scale(_hist_ups2_xi, 1. / *_weightSum_Ups2);
  }
  if (_weightSum_cont->val()) {
    scale(_hist_cont_lambda1, 1. / *_weightSum_cont);
    scale(_hist_cont_lambda2, 1. / *_weightSum_cont);
    scale(_hist_cont_xi, 1. / *_weightSum_cont);
  }
}

/// @}


/// @name Histograms
/// @{
Histo1DPtr _hist_ups1_lambda, _hist_ups2_lambda, _hist_cont_lambda1, _hist_cont_lambda2;
Histo1DPtr _hist_ups1_xi, _hist_ups2_xi, _hist_cont_xi;
BinnedHistoPtr<int> _mult[2][7];
CounterPtr _weightSum_cont, _weightSum_Ups1, _weightSum_Ups2;
const int Ecms = 10;
/// @}

};

RIVET_DECLARE_PLUGIN(ARGUS_1988_I251097);

} ```