Rivet analyses

D^0, + → π⁺π⁺π⁻ + X decays

Experiment: BESIII (BEPC)

Inspire ID: 2621481

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - arXiv: :2301.03214

Beams: e+ e-

Beam energies: (2.4, 2.4)GeV

Run details: - Needs e+e- events at 4.773 due cuts

Measurement of mass and momentum distributions in D^0, + → π⁺π⁺π⁻ + X decays. The mass distribution was read from table VII in the paper and is corrected while the momentum distributions were extracted from the figures and are background subtracted but not corrected.

Source code:`BESIII_2023_I2621481.cc`

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

namespace Rivet {


  /// @brief D0,+ -> pi+ pi+ pi- +X
  class BESIII_2023_I2621481 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2023_I2621481);


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

    /// Book histograms and initialise projections before the run
    void init() {
      // projections
      declare(UnstableParticles(Cuts::abspid==411 or
                Cuts::abspid==421),"UFS");
      // histos
      for(unsigned int ix=0;ix<2;++ix) {
    book(_h_br  [ix],1,1,1+ix);
    book(_h_mass[ix],2,1,1+ix);
    for(unsigned int iy=0;iy<3;++iy)
      book(_h_mom[ix][iy],3,1+ix,1+iy);
    book(_c[ix],"TMP/nD_"+toString(ix+1));
      }
    }
    
    void findChildren(const Particle & p, Particles & piPlus, Particles & piMinus) {
      for( const Particle &child : p.children()) {
    if(child.pid()==PID::PIPLUS) {
      piPlus.push_back(child);
    }
    else if(child.pid()==PID::PIMINUS) {
      piMinus.push_back(child);
    }
    else if(child.pid()==PID::K0S || child.pid()==PID::K0L)
      continue;
    else if(!child.children().empty())
      findChildren(child,piPlus,piMinus);
      }
    }

    /// Perform the per-event analysis
    void analyze(const Event& event) {
      for (const Particle& p :  apply<FinalState>(event, "UFS").particles()) {
    unsigned int iloc = p.abspid()==421 ? 0 : 1;
    _c[iloc]->fill();
    Particles piPlus,piMinus;
    findChildren(p,piPlus,piMinus);
    if(p.pid()<0) swap(piPlus,piMinus);
    if(piPlus.size()>=2 && !piMinus.empty()) {
      _h_br[iloc]->fill();
      sortBy(piMinus,cmpMomByP);
      sortBy(piPlus ,cmpMomByP);
      _h_mom[iloc][2]->fill(piMinus[0].p3().mod());
      for(unsigned int ix=0;ix<2;++ix)
        _h_mom[iloc][ix]->fill(piPlus[ix].p3().mod());
      double mass = (piMinus[0].momentum()+piPlus[0].momentum()+piPlus[1].momentum()).mass();
      _h_mass[iloc]->fill(mass);
    }
      }
    }

    /// Normalise histograms etc., after the run
    void finalize() {
      for(unsigned int ix=0;ix<2;++ix) {
    scale(_h_br  [ix], 100./ *_c[ix]);
    scale(_h_mass[ix], 100./ *_c[ix]);
    for(unsigned int iy=0;iy<3;++iy)
      normalize(_h_mom[ix][iy],1.,false);
      }
    }

    /// @}


    /// @name Histograms
    /// @{
    CounterPtr _h_br[2];
    Histo1DPtr _h_mass[2],_h_mom[2][3];
    CounterPtr _c[2];
    /// @}


  };


  RIVET_DECLARE_PLUGIN(BESIII_2023_I2621481);

}

Rivet analyses

D0, + → π+π+π− + X decays

Source code:BESIII_2023_I2621481.cc

D^0, + → π⁺π⁺π⁻ + X decays

Source code:`BESIII_2023_I2621481.cc`