Rivet analyses

Dalitz plot analysis of Υ(5S) → Υ(1, 2, 3S)π0π0

Experiment: BELLE (KEKB)

Inspire ID: 1247463

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Phys.Rev.D 88 (2013) 5, 052016

Beams: * *

Beam energies: ANY

Run details: - Any process producing Upsilon(5S), originally e+e-

Measurement of the mass distributions in the decays Υ(5S) → Υ(1, 2, 3S)π0π0 by BELLE.

Source code:BELLE_2013_I1247463.cc

// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/DecayedParticles.hh"
#include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {


  /// @brief Upsilon(5S) -> Upsilon(nS) pi0 pi0
  class BELLE_2013_I1247463 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(BELLE_2013_I1247463);


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

    /// Book histograms and initialise projections before the run
    void init() {
      // Initialise and register projections
      UnstableParticles ufs = UnstableParticles(Cuts::abspid == 9000553);
      declare(ufs, "UFS");
      DecayedParticles UPS(ufs);
      UPS.addStable(PID::PI0);
      UPS.addStable(553);
      UPS.addStable(100553);
      UPS.addStable(200553);
      declare(UPS, "UPS");
      // histograms
      for (unsigned int ix = 0; ix < 3; ++ix)
        for (unsigned int iy = 0; iy < 3; ++iy) book(_h[ix][iy], 1 + ix, 1, 1 + iy);
    }


    /// Perform the per-event analysis
    void analyze(const Event& event) {
      // find the Upsilon(5S) decays
      static const map<PdgId, unsigned int> mode[3] = {{{553, 1}, {111, 2}},
                                                       {{100553, 1}, {111, 2}},
                                                       {{200553, 1}, {111, 2}}};
      DecayedParticles UPS = apply<DecayedParticles>(event, "UPS");
      for (unsigned int ix = 0; ix < UPS.decaying().size(); ++ix) {
        unsigned int imode;
        for (imode = 0; imode < 3; ++imode) {
          if (UPS.modeMatches(ix, 3, mode[imode])) break;
        }
        if (imode > 2) continue;
        const Particles& pi0 = UPS.decayProducts()[ix].at(111);
        const Particle& ups = UPS.decayProducts()[ix].at(553 + imode * 100000)[0];
        double mUpsPi[2];
        for (unsigned int iy = 0; iy < 2; ++iy) mUpsPi[iy] = (ups.momentum() + pi0[iy].momentum()).mass();
        if (mUpsPi[0] < mUpsPi[1]) swap(mUpsPi[0], mUpsPi[1]);
        _h[imode][0]->fill(mUpsPi[0]);
        _h[imode][1]->fill((pi0[0].momentum() + pi0[1].momentum()).mass());
        _h[imode][2]->fill(mUpsPi[1]);
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      for (unsigned int ix = 0; ix < 3; ++ix)
        for (unsigned int iy = 0; iy < 3; ++iy) normalize(_h[ix][iy], 1., false);
    }

    /// @}


    /// @name Histograms
    /// @{
    Histo1DPtr _h[3][3];
    /// @}
  };


  RIVET_DECLARE_PLUGIN(BELLE_2013_I1247463);

}