Rivet analyses

Momentum spectra for J/ψ, ψ(2S) and χc1 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/ψ, ψ(2S) and χc1 production in B decays at the Υ(4S)

Source code:CLEOII_1995_I382221.cc

// -*- 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);

}