Rivet analyses

title: CLEOII_1995_I382221

Momentum spectra for $J/\psi$, $\psi(2S)$ and $\chi_{c1}$ production in $B$ decays

Experiment: CLEOII (CESR)

Inspire ID: 382221

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Phys.Rev.D 52 (1995) 2661-2672

Beams: * *

Beam energies: ANY

Run details: - any process with Upsilon(4S) decay, originally e+e-

Momentum Spectra for $J/\psi$, $\psi(2S)$ and $\chi_{c1}$ production in B decays at the $\Upsilon(4S)$

Source code:CLEOII_1995_I382221.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief J/Psi, Psi(2S), chi_c1 spectra at the Upsilon(4S) class CLEOII_1995_I382221 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(CLEOII_1995_I382221);


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

/// Book histograms and initialise projections before the run
void init() {
  // projections
  declare(UnstableParticles(Cuts::pid == 300553), "UFS");
  // histos
  for (unsigned int ix = 0; ix < 4; ++ix) {
    book(_h[ix], 1 + ix, 1, 1);
  }
  book(_c, "TMP/nUps");
}

void findDecayProducts(Particle parent, Particles& primary, Particles& secondary, bool second) {
  for (const Particle& p : parent.children()) {
    if (p.pid() == 443) {
      if (second)
        secondary.push_back(p);
      else
        primary.push_back(p);
      continue;
    }
    else if (p.pid() == 100443 || p.pid() == 20443) {
      if (second)
        secondary.push_back(p);
      else
        primary.push_back(p);
      findDecayProducts(p, primary, secondary, true);
    }
    else if (p.pid() == 10441 || p.pid() == 445) {
      findDecayProducts(p, primary, secondary, true);
    }
    else if (!p.children().empty()) {
      findDecayProducts(p, primary, secondary, second);
    }
  }
}


/// Perform the per-event analysis
void analyze(const Event& event) {
  const UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");
  for (const Particle& p : ufs.particles()) {
    _c->fill();
    const LorentzTransform boost = LorentzTransform::mkFrameTransformFromBeta(p.mom().betaVec());
    Particles primary, secondary;
    findDecayProducts(p, primary, secondary, false);
    for (const Particle& pp : primary) {
      const double pcm = boost.transform(pp.mom()).p3().mod();
      if (pp.pid() == 443) {
        _h[0]->fill(pcm);
        _h[1]->fill(pcm);
      }
      else if (pp.pid() == 100443)
        _h[2]->fill(pcm);
      else if (pp.pid() == 20443)
        _h[3]->fill(pcm);
    }
    for (const Particle& pp : secondary) {
      const double pcm = boost.transform(pp.mom()).p3().mod();
      if (pp.pid() == 443)
        _h[0]->fill(pcm);
      else if (pp.pid() == 100443)
        _h[2]->fill(pcm);
      else if (pp.pid() == 20443)
        _h[3]->fill(pcm);
    }
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  // 100 convert to % and 0.5 as 2 B decays per Upslion(4S)
  scale(_h, 50. / *_c);
}

/// @}


/// @name Histograms
/// @{
Histo1DPtr _h[4];
CounterPtr _c;
/// @}

};

RIVET_DECLARE_PLUGIN(CLEOII_1995_I382221);

} ```