Rivet analyses

title: CLEOII_1994_I356001

Pion mass spectra for $\Upsilon(3S)\to\Upsilon(1,2S)\pi^+\pi^-$, $\Upsilon(3S)\to\Upsilon(1,2S)\pi^0\pi^0$ and $\Upsilon(2S)\to\Upsilon(1S)\pi^+\pi^-$

Experiment: CLEOII (CESR)

Inspire ID: 356001

Status: VALIDATED

Authors: - Peter Richardson

References: - Phys.Rev. D49 (1994) 40-57

Beams: * *

Beam energies: ANY

Run details: - Any process producing Upsilon(3S) or Upsilon(2S)

Measurement of the pion mass spectra for the decays $\Upsilon(3S)\to\Upsilon(1,2S)\pi^+\pi^-$, $\Upsilon(3S)\to\Upsilon(1,2S)\pi^0\pi^0$ and $\Upsilon(2S)\to\Upsilon(1S)\pi^+\pi^-$ by the CLEO-II collaboration.

Source code:CLEOII_1994_I356001.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief Add a short analysis description here class CLEOII_1994_I356001 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(CLEOII_1994_I356001);


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

/// Book histograms and initialise projections before the run
void init() {
  // Initialise and register projections
  declare(UnstableParticles(), "UFS");
  // Histograms
  book(_n_2S, "/TMP/n_2S");
  book(_n_3S, "/TMP/n_3S");
  book(_h_3S_1S_neutral, 1, 1, 1);
  book(_h_3S_2S_neutral, 1, 1, 2);
  book(_h_3S_1S_ex, 2, 1, 1);
  book(_h_3S_1S_in, 2, 1, 2);
  book(_h_3S_2S_ex, 3, 1, 1);
  book(_h_3S_2S_in, 3, 1, 2);
  book(_h_2S_1S_ex, 4, 1, 1);
  book(_h_2S_1S_in, 4, 1, 2);
}

void findDecayProducts(const Particle& mother,
                       unsigned int& nstable,
                       Particles& pip,
                       Particles& pim,
                       Particles& pi0,
                       Particles& onium) {
  for (const Particle& p : mother.children()) {
    int id = p.pid();
    if (id == PID::PIMINUS) {
      pim.push_back(p);
      ++nstable;
    }
    else if (id == PID::PIPLUS) {
      pip.push_back(p);
      ++nstable;
    }
    else if (id == PID::PI0) {
      pi0.push_back(p);
      ++nstable;
    }
    else if (abs(id) % 1000 == 553) {
      onium.push_back(p);
      ++nstable;
    }
    else if (!p.children().empty()) {
      findDecayProducts(p, nstable, pip, pim, pi0, onium);
    }
    else
      ++nstable;
  }
}

/// Perform the per-event analysis
void analyze(const Event& event) {
  // loop over unstable particles
  for (const Particle& ups :
       apply<UnstableParticles>(event, "UFS").particles(Cuts::pid == 100553 or Cuts::pid == 200553)) {
    if (ups.pid() == 200553)
      _n_3S->fill();
    else
      _n_2S->fill();
    unsigned int nstable(0);
    Particles pip, pim, pi0, onium;
    findDecayProducts(ups, nstable, pip, pim, pi0, onium);
    // check for onium
    if (onium.size() != 1 || nstable != 3) continue;
    //pi+pi-
    if (pip.size() == 1 && pim.size() == 1) {
      double q = (pip[0].momentum() + pim[0].momentum()).mass();
      if (ups.pid() == 200553 && onium[0].pid() == 553) {
        _h_3S_1S_ex->fill(q);
        _h_3S_1S_in->fill(q);
      }
      else if (ups.pid() == 200553 && onium[0].pid() == 100553) {
        _h_3S_2S_ex->fill(q);
        _h_3S_2S_in->fill(q);
      }
      else if (ups.pid() == 100553 && onium[0].pid() == 553) {
        _h_2S_1S_ex->fill(q);
        _h_2S_1S_in->fill(q);
      }
    }
    else if (pi0.size() == 2) {
      double q = (pi0[0].momentum() + pi0[1].momentum()).mass();
      if (ups.pid() == 200553 && onium[0].pid() == 553) {
        _h_3S_1S_neutral->fill(q);
      }
      else if (ups.pid() == 200553 && onium[0].pid() == 100553) {
        _h_3S_2S_neutral->fill(q);
      }
    }
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  // widths of Upsilon 2S and 3S
  vector<double> width = {31.98, 20.32};
  scale(_h_3S_2S_neutral, width[1] / *_n_3S);
  scale(_h_3S_1S_neutral, width[1] / *_n_3S);
  scale(_h_3S_2S_ex, width[1] / *_n_3S);
  scale(_h_3S_2S_in, width[1] / *_n_3S);
  scale(_h_3S_1S_ex, width[1] / *_n_3S);
  scale(_h_3S_1S_in, width[1] / *_n_3S);
  scale(_h_2S_1S_ex, width[0] / *_n_2S);
  scale(_h_2S_1S_in, width[0] / *_n_2S);
}

/// @}


/// @name Histograms
/// @{
CounterPtr _n_3S, _n_2S;
Histo1DPtr _h_3S_2S_neutral, _h_3S_1S_neutral;
Histo1DPtr _h_3S_2S_ex, _h_3S_2S_in, _h_3S_1S_ex, _h_3S_1S_in;
Histo1DPtr _h_2S_1S_ex, _h_2S_1S_in;
/// @}

};

RIVET_DECLARE_PLUGIN(CLEOII_1994_I356001);

} ```