Rivet analyses

Pion mass spectra for Υ(3S) → Υ(1, 2S)π+π−, Υ(3S) → Υ(1, 2S)π0π0 and Υ(2S) → Υ(1S)π+π−

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 Υ(3S) → Υ(1, 2S)π+π−, Υ(3S) → Υ(1, 2S)π0π0 and Υ(2S) → Υ(1S)π+π− by the CLEO-II collaboration.

Source code:CLEOII_1994_I356001.cc

// -*- 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);

}