Rivet analyses

D_s⁺ → π⁺π⁺π⁻ + X decays

Experiment: BESIII (BEPC)

Inspire ID: 2618227

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - arXiv: 2212.13072

Beams: e+ e-

Beam energies: (2.1, 2.1)GeV

Run details: - Needs e+e- events at 4.178 due cuts

Measurement of mass and momentum distributions in D_s⁺ → 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_2022_I2618227.cc`

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

namespace Rivet {


  /// @brief D_s -> pi+ pi+ pi- +X
  class BESIII_2022_I2618227 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2022_I2618227);


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

    /// Book histograms and initialise projections before the run
    void init() {
      // projections
      declare(UnstableParticles(Cuts::abspid==431),"UFS");
      // histos
      book(_h_br,1,1,1);
      book(_h_mass,2,1,1);
      for(unsigned int ix=0;ix<3;++ix)
    book(_h_mom[ix],3,1,1+ix);
      book(_c,"TMP/nDs");
    }
    
    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()) {
    _c->fill();
    Particles piPlus,piMinus;
    findChildren(p,piPlus,piMinus);
    if(p.pid()<0) swap(piPlus,piMinus);
    if(piPlus.size()>=2 && !piMinus.empty()) {
      _h_br->fill();
      sortBy(piMinus,cmpMomByP);
      sortBy(piPlus ,cmpMomByP);
      _h_mom[0]->fill(piMinus[0].p3().mod());
      for(unsigned int ix=0;ix<2;++ix)
        _h_mom[1+ix]->fill(piPlus[ix].p3().mod());
      double mass = (piMinus[0].momentum()+piPlus[0].momentum()+piPlus[1].momentum()).mass();
      _h_mass->fill(mass);
    }
      }
    }


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

    /// @}


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


  };


  RIVET_DECLARE_PLUGIN(BESIII_2022_I2618227);

}

Rivet analyses

Ds+ → π+π+π− + X decays

Source code:BESIII_2022_I2618227.cc

D_s⁺ → π⁺π⁺π⁻ + X decays

Source code:`BESIII_2022_I2618227.cc`