Rivet analyses

title: ARGUS_1989_I262551

Spectra for $\phi$ meson production for $e^+e^-$ collisions in the continuum at 10 GeV and at $\Upsilon_{1,2}$

Experiment: ARGUS (DORIS)

Inspire ID: 262551

Status: VALIDATED

Authors: - Peter Richardson

References: - Z.Phys. C41 (1989) 557, 1989

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 spectrum for $\phi$ mesons in the $e^+e^-$ continuum at 10 GeV and in $\Upsilon(1S)$ and $\Upsilon(2S)$ decays.

Source code:ARGUS_1989_I262551.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief phi spectrum in continuum, and Upsilon 1s and 2s decays class ARGUS_1989_I262551 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(ARGUS_1989_I262551);


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

/// Book histograms and initialise projections before the run
void init() {
  // Initialise and register projections
  declare(UnstableParticles(), "UFS");
  // Book histograms
  book(_h_cont, 1, 1, 1);
  book(_h_ups1, 2, 1, 1);
  book(_h_ups2, 2, 1, 2);
  book(_n_Phi[0], 3, 1, 1);
  book(_n_Phi[1], 4, 1, 1);
  book(_weightSum_cont, "TMP/weightSum_cont");
  book(_weightSum_Ups1, "TMP/weightSum_Ups1");
  book(_weightSum_Ups2, "TMP/weightSum_Ups2");
}

/// Recursively walk the decay tree to find decay products of @a p
void findDecayProducts(Particle mother, Particles& phis) {
  for (const Particle& p : mother.children()) {
    const int id = p.pid();
    if (id == 333) {
      phis.push_back(p);
    }
    if (!p.children().empty()) {
      findDecayProducts(p, phis);
    }
  }
}

/// Perform the per-event analysis
void analyze(const Event& event) {
  // Find the Upsilons among the unstables
  const UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");
  Particles upsilons = ufs.particles(Cuts::pid == 553 or Cuts::pid == 100553);
  // Continuum
  if (upsilons.empty()) {
    MSG_DEBUG("No Upsilons found => continuum event");
    _weightSum_cont->fill();
    for (const Particle& p : ufs.particles(Cuts::pid == 333)) {
      const double xp = 2. * p.E() / sqrtS();
      const double beta = p.p3().mod() / p.E();
      _h_cont->fill(xp, 1. / beta);
    }
  }
  // Upsilon(s) found
  else {
    MSG_DEBUG("Upsilons found => resonance event");
    for (const Particle& ups : upsilons) {
      const int parentId = ups.pid();
      if (parentId == 553) {
        _weightSum_Ups1->fill();
      }
      else {
        _weightSum_Ups2->fill();
      }
      Particles phis;
      // Find the decay products we want
      findDecayProducts(ups, phis);
      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 : phis) {
        const FourMomentum p2 = cms_boost.transform(p.momentum());
        const double xp = 2. * p2.E() / mass;
        const double beta = p2.p3().mod() / p2.E();
        if (parentId == 553) {
          _n_Phi[0]->fill(Ecm9);
          _h_ups1->fill(xp, 1. / beta);
        }
        else {
          _n_Phi[1]->fill(Ecm10);
          _h_ups2->fill(xp, 1. / beta);
        }
      }
    }
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  if (_weightSum_cont->effNumEntries() > 0.)
    scale(_h_cont, sqr(sqrtS()) * crossSection() / microbarn / sumOfWeights());
  if (_weightSum_Ups1->effNumEntries() > 0.) {
    scale(_h_ups1, 1. / *_weightSum_Ups1);
  }
  if (_weightSum_Ups2->effNumEntries() > 0.) {
    scale(_h_ups2, 1. / *_weightSum_Ups2);
  }
  // Counters
  vector<CounterPtr> scales = {_weightSum_Ups1, _weightSum_Ups2};
  for (unsigned int ix = 0; ix < 2; ++ix) {
    scale(_n_Phi[ix], 1. / *scales[ix]);
  }
}

/// @}


/// @name Histograms
/// @{
Histo1DPtr _h_cont, _h_ups1, _h_ups2;
BinnedHistoPtr<string> _n_Phi[2];
CounterPtr _weightSum_cont, _weightSum_Ups1, _weightSum_Ups2;
const string Ecm9 = "9.46", Ecm10 = "10.023";
/// @}

};

RIVET_DECLARE_PLUGIN(ARGUS_1989_I262551);

} ```