Rivet analyses

title: ARGUS_1989_I276860

Spectra for $\pi^\pm$, $K^\pm$, $K^0_S$ and $\bar{p}$ in $e^+e^-$ collisions at the $\Upsilon(1S)$ and continuum

Experiment: ARGUS (DORIS)

Inspire ID: 276860

Status: VALIDATED

Authors: - Peter Richardson

References: - Z.Phys. C44 (1989) 547, 1989

Beams: e- e+

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

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

Spectra for the production of $\pi^\pm$, $K^\pm$, $K^0_S$ and $\bar{p}$ in $e^+e^-$ collisions. Data are taken on the $\Upsilon(1S)$ and in the nearby continuum.

Source code:ARGUS_1989_I276860.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/FinalState.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief pi+- K+- K0S pbar spectra continuum and Upsilon 1s class ARGUS_1989_I276860 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(ARGUS_1989_I276860);


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

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

  // Initialise and register projections
  declare(FinalState(), "FS");
  declare(UnstableParticles(), "UFS");
  // Book histograms
  book(_h_pi_ups1_p, 5, 1, 1);
  book(_h_pi_cont_p, 5, 1, 2);
  book(_h_pi_ups1_z, 9, 1, 1);
  book(_h_pi_cont_z, 9, 1, 2);

  book(_h_Kp_ups1_p, 6, 1, 1);
  book(_h_Kp_cont_p, 6, 1, 2);
  book(_h_Kp_ups1_z, 10, 1, 1);
  book(_h_Kp_cont_z, 10, 1, 2);

  book(_h_KS_ups1_p, 7, 1, 1);
  book(_h_KS_cont_p, 7, 1, 2);
  book(_h_KS_ups1_z, 11, 1, 1);
  book(_h_KS_cont_z, 11, 1, 2);

  book(_h_pt_ups1_p, 8, 1, 1);
  book(_h_pt_cont_p, 8, 1, 2);
  book(_h_pt_ups1_z, 12, 1, 1);
  book(_h_pt_cont_z, 12, 1, 2);

  // Counters
  book(_n_PiA, 1, 1, 1);
  book(_n_PiB, 1, 1, 2);
  book(_n_KS, 2, 1, 1);
  book(_n_Kp, 3, 1, 1);
  book(_n_ptA, 4, 1, 1);
  book(_n_ptB, 4, 1, 2);

  // weights
  book(_weightSum_cont, "/TMP/weightSum_cont");
  book(_weightSum_Ups1, "/TMP/weightSum_Ups1");
}

/// 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 == 211 || id == 2212 || id == 310 || id == 130 || id == 321) {
      unstable.push_back(p);
    }
    if (!p.children().empty()) findDecayProducts(p, unstable);
  }
}


/// Perform the per-event analysis
void analyze(const Event& event) {
  // Find the Upsilons among the unstables
  const UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");
  const FinalState& fs = apply<FinalState>(event, "FS");
  Particles upsilons = ufs.particles(Cuts::pid == 553);
  // Continuum
  if (upsilons.empty()) {
    MSG_DEBUG("No Upsilons found => continuum event");
    _weightSum_cont->fill();
    // stable particles
    for (const Particle& p :
         fs.particles(Cuts::abspid == 211 or Cuts::abspid == 2212 or Cuts::abspid == 321)) {
      const int id = abs(p.pid());
      const double xE = 2. * p.E() / sqrtS();
      const double modp = p.p3().mod();
      const double beta = modp / p.E();
      int idMom = !p.parents().empty() ? abs(p.parents()[0].pid()) : 0;
      if (id == 211) {
        // not from K0S or Lambda decays
        if (idMom != 310 && idMom != 3122) {
          _h_pi_cont_p->fill(modp);
          _h_pi_cont_z->fill(xE, 1. / beta);
          _n_PiA->fill("9.98"s);
        }
        _n_PiB->fill("9.98"s);
      }
      else if (id == 321) {
        _h_Kp_cont_p->fill(modp);
        _h_Kp_cont_z->fill(xE, 1. / beta);
        _n_Kp->fill("9.98"s);
      }
      else if (id == 2212) {
        // not from K0S or Lambda decays
        if (idMom != 310 && idMom != 3122) {
          _h_pt_cont_p->fill(modp);
          _h_pt_cont_z->fill(xE, 1. / beta);
          _n_ptA->fill("9.98"s);
        }
        _n_ptB->fill("9.98"s);
      }
    }
    // Unstable particles
    for (const Particle& p : ufs.particles(Cuts::pid == 310 || Cuts::pid == 130)) {
      const double xE = 2. * p.E() / sqrtS();
      const double modp = p.p3().mod();
      const double beta = modp / p.E();
      _h_KS_cont_p->fill(modp);
      _h_KS_cont_z->fill(xE, 1. / beta);
      _n_KS->fill("9.98"s);
    }
  }
  // Upsilon(s) found
  else {
    MSG_DEBUG("Upsilons found => resonance event");
    for (const Particle& ups : upsilons) {
      _weightSum_Ups1->fill();
      Particles unstable;
      // Find the decay products we want
      findDecayProducts(ups, unstable);
      LorentzTransform cms_boost;
      if (ups.p3().mod() > 1 * MeV)
        cms_boost = LorentzTransform::mkFrameTransformFromBeta(ups.momentum().betaVec());
      const double mass = ups.mass();
      // loop over decay products
      for (const Particle& p : unstable) {
        const int id = abs(p.pid());
        const FourMomentum p2 = cms_boost.transform(p.momentum());
        const double xE = 2. * p2.E() / mass;
        const double modp = p2.p3().mod();
        const double beta = modp / p2.E();
        int idMom = !p.parents().empty() ? abs(p.parents()[0].pid()) : 0;
        if (id == 211) {
          // not from K0S or Lambda decays
          if (idMom != 310 && idMom != 3122) {
            _h_pi_ups1_p->fill(modp);
            _h_pi_ups1_z->fill(xE, 1. / beta);
            _n_PiA->fill("9.46"s);
          }
          _n_PiB->fill("9.46"s);
        }
        else if (id == 321) {
          _h_Kp_ups1_p->fill(modp);
          _h_Kp_ups1_z->fill(xE, 1. / beta);
          _n_Kp->fill("9.46"s);
        }
        else if (id == 2212) {
          // not from K0S or Lambda decays
          if (idMom != 310 && idMom != 3122) {
            _h_pt_ups1_p->fill(modp);
            _h_pt_ups1_z->fill(xE, 1. / beta);
            _n_ptA->fill("9.46"s);
          }
          _n_ptB->fill("9.46"s);
        }
        else if (id == 310 || id == 130) {
          _h_KS_ups1_p->fill(modp);
          _h_KS_ups1_z->fill(xE, 1. / beta);
          _n_KS->fill("9.46"s);
        }
      }
    }
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  // Scale histos
  if (_weightSum_cont->val() > 0.) {
    scale(_h_pi_cont_p, 1. / *_weightSum_cont);
    scale(_h_Kp_cont_p, 1. / *_weightSum_cont);
    scale(_h_KS_cont_p, 1. / *_weightSum_cont);
    scale(_h_pt_cont_p, 1. / *_weightSum_cont);
    scale(_h_pi_cont_z, 1. / *_weightSum_cont);
    scale(_h_Kp_cont_z, 1. / *_weightSum_cont);
    scale(_h_KS_cont_z, 1. / *_weightSum_cont);
    scale(_h_pt_cont_z, 1. / *_weightSum_cont);
  }
  if (_weightSum_Ups1->val() > 0.) {
    scale(_h_pi_ups1_p, 1. / *_weightSum_Ups1);
    scale(_h_Kp_ups1_p, 1. / *_weightSum_Ups1);
    scale(_h_KS_ups1_p, 1. / *_weightSum_Ups1);
    scale(_h_pt_ups1_p, 1. / *_weightSum_Ups1);
    scale(_h_pi_ups1_z, 1. / *_weightSum_Ups1);
    scale(_h_Kp_ups1_z, 1. / *_weightSum_Ups1);
    scale(_h_KS_ups1_z, 1. / *_weightSum_Ups1);
    scale(_h_pt_ups1_z, 1. / *_weightSum_Ups1);
  }
  // Counters
  vector<CounterPtr> scales = {_weightSum_Ups1, _weightSum_cont};
  vector<string> labels = {"9.46", "9.98"};
  for (unsigned int ix = 0; ix < 2; ++ix) {
    _n_PiA->binAt(labels[ix]).scaleW(1. / scales[ix]->val());
    _n_PiB->binAt(labels[ix]).scaleW(1. / scales[ix]->val());
    _n_Kp->binAt(labels[ix]).scaleW(1. / scales[ix]->val());
    _n_KS->binAt(labels[ix]).scaleW(1. / scales[ix]->val());
    _n_ptA->binAt(labels[ix]).scaleW(1. / scales[ix]->val());
    _n_ptB->binAt(labels[ix]).scaleW(1. / scales[ix]->val());
  }
}

/// @}


/// @name Histograms
/// @{
Histo1DPtr _h_pi_ups1_p, _h_pi_cont_p, _h_pi_ups1_z, _h_pi_cont_z;
Histo1DPtr _h_Kp_ups1_p, _h_Kp_cont_p, _h_Kp_ups1_z, _h_Kp_cont_z;
Histo1DPtr _h_KS_ups1_p, _h_KS_cont_p, _h_KS_ups1_z, _h_KS_cont_z;
Histo1DPtr _h_pt_ups1_p, _h_pt_cont_p, _h_pt_ups1_z, _h_pt_cont_z;

// Counters
BinnedHistoPtr<string> _n_PiA, _n_PiB, _n_Kp, _n_KS, _n_ptA, _n_ptB;
CounterPtr _weightSum_cont, _weightSum_Ups1;
/// @}

};

RIVET_DECLARE_PLUGIN(ARGUS_1989_I276860);

} ```