Rivet analyses

title: CLEO_1982_I180612

Kaon momentum spectrum at the $\Upsilon(4S)$ and nearby continuum

Experiment: CLEO (CESR)

Inspire ID: 180612

Status: VALIDATED

Authors: - Peter Richardson

References: - Phys.Rev.Lett. 48 (1982) 1070-1074

Beams: e+ e-

Beam energies: (5.2, 5.2); (5.3, 5.3)GeV

Run details: - e+ e- to hadrons in the Upsilon(4S) region, below resonance and Upsilon(4S) decays

Measurement of charged and neutral kaon spectra in $\Upsilon(4S)$ decays and the nearby continumm.

Source code:CLEO_1982_I180612.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief kaon spetra at Upsilon(4S) and nearby continuum class CLEO_1982_I180612 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(CLEO_1982_I180612);


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

/// Book histograms and initialise projections before the run
void init() {
  // projections
  declare(UnstableParticles(), "UFS");
  // histos
  for (unsigned int ix = 0; ix < 2; ++ix) {
    book(_c[ix], "TMP/c_" + toString(ix + 1));
    book(_h_mult[ix], 1, 1, ix + 1);
    for (unsigned int iy = 0; iy < 2; ++iy) {
      book(_h[ix][iy], 2, 1 + iy, 1 + ix);
    }
  }
}

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

/// Perform the per-event analysis
void analyze(const Event& event) {
  const UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");
  Particles upsilons = ufs.particles(Cuts::pid == 300553);
  // continuum
  if (upsilons.empty()) {
    _c[0]->fill();
    for (const Particle& p : ufs.particles(Cuts::pid == 130 || Cuts::pid == 310 || Cuts::abspid == 321)) {
      int id = p.abspid();
      double modp = p.p3().mod();
      if (id == 321) {
        _h[0][0]->fill(modp);
        _h_mult[0]->fill(_edges[0]);
      }
      else {
        _h[0][1]->fill(modp);
        _h_mult[0]->fill(_edges[1]);
      }
    }
  }
  /// found an upsilon
  else {
    for (const Particle& ups : upsilons) {
      _c[1]->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());
      }
      for (const Particle& p : unstable) {
        int id = p.abspid();
        double modp = cms_boost.transform(p.momentum()).p3().mod();
        if (id == 321) {
          _h[1][0]->fill(modp);
          _h_mult[1]->fill(_edges[0]);
        }
        else {
          _h[1][1]->fill(modp);
          _h_mult[1]->fill(_edges[1]);
        }
      }
    }
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  for (unsigned int ix = 0; ix < 2; ++ix) {
    scale(_h_mult[ix], 1. / *_c[ix]);
    for (unsigned int iy = 0; iy < 2; ++iy) {
      scale(_h[ix][iy], crossSection() / nanobarn / sumOfWeights());
    }
  }
}

/// @}


/// @name Histograms
/// @{
Histo1DPtr _h[2][2];
BinnedHistoPtr<string> _h_mult[2];
CounterPtr _c[2];
vector<string> _edges = {"E+ E- --> (K+ + K-) X", "E+ E- --> K0 X"};
/// @}

};

RIVET_DECLARE_PLUGIN(CLEO_1982_I180612);

} ```