Rivet analyses

Mass distributions in the decay D_s⁺ → K⁺K⁻π⁺π⁺π⁻

Experiment: BESIII (BEPC)

Inspire ID: 2051683

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - arXiv: 2203.06688

Beams: * *

Beam energies: ANY

Run details: - Any process producing D_s+ mesons

Measurement of the mass distributions in the decay D_s⁺ → K⁺K⁻π⁺π⁺π⁻ by BES. The data were read from the plots in the paper and therefore for some points the error bars are the size of the point. It is also not clear that any resolution effects have been unfolded.

Source code:`BESIII_2022_I2051683.cc`

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

namespace Rivet {


  /// @brief Ds -> K+K-pi+pi+pi-
  class BESIII_2022_I2051683 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2022_I2051683);


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

    /// Book histograms and initialise projections before the run
    void init() {
      // Initialise and register projections
      declare(UnstableParticles(), "UFS");
      for(unsigned int ix=0;ix<10;++ix)
    book(_h[ix],1,1,1+ix);
    }

    void findDecayProducts(const Particle & mother, unsigned int & nstable,
               Particles & pip , Particles & pim ,
               Particles & Kp  , Particles & Km  ) {
      for(const Particle & p : mother.children()) {
        int id = p.pid();
        if ( id == PID::KPLUS ) {
          Kp.push_back(p);
      ++nstable;
    }
    else if (id == PID::KMINUS ) {
      Km.push_back(p);
      ++nstable;
    }
    else if (id == PID::PIPLUS) {
      pip.push_back(p);
      ++nstable;
    }
    else if (id == PID::PIMINUS) {
      pim.push_back(p);
      ++nstable;
    }
    else if (id == PID::PI0 || id == PID::K0S||id == PID::K0L) {
          ++nstable;
        }
    else if ( !p.children().empty() ) {
      findDecayProducts(p, nstable, pip, pim, Kp , Km);
    }
    else
      ++nstable;
      }
    }

    /// Perform the per-event analysis
    void analyze(const Event& event) {
      for(const Particle& meson : apply<UnstableParticles>(event, "UFS").particles(Cuts::abspid== 431)) {
    unsigned int nstable(0);
    Particles pip, pim, Kp , Km;
    findDecayProducts(meson, nstable, pip, pim, Kp , Km);
    if (nstable!=5) continue;
    if(meson.pid()<0) {
      swap(pim,pip);
      swap(Kp,Km);
    }
    if(pip.size()==2&&Km.size()==1&&Kp.size()==1&&pim.size()==1) {
      double mpippim[2] = {(pim[0].momentum()+pip[0].momentum()).mass(), 
                   (pim[0].momentum()+pip[1].momentum()).mass()};
      if(mpippim[0]>mpippim[1]) {
        swap(  pip[0],  pip[1]);
        swap(mpippim[0],mpippim[1]);
      }
      double mKK = (Kp[0].momentum()+Km[0].momentum()).mass();
      _h[0]->fill(mKK);
      _h[1]->fill(mKK);
      _h[2]->fill(mpippim[0]);
      _h[3]->fill(mpippim[1]);
      _h[4]->fill((Kp [0].momentum()+Km [0].momentum()+pim[0].momentum()).mass());
      _h[5]->fill((Km [0].momentum()+pip[1].momentum()+pim[0].momentum()).mass());
      _h[6]->fill((Kp [0].momentum()+pip[0].momentum()+pim[0].momentum()).mass());
      _h[7]->fill((pim[0].momentum()+pip[0].momentum()+pip[1].momentum()).mass());
      _h[8]->fill((Kp [0].momentum()+Km [0].momentum()+pip[1].momentum()+pim[0].momentum()).mass());
      _h[9]->fill((Km [0].momentum()+pip[0].momentum()+pip[1].momentum()+pim[0].momentum()).mass());
    }
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      for(unsigned int ix=0;ix<10;++ix)
    normalize(_h[ix],1.,false);
    }

    /// @}


    /// @name Histograms
    /// @{
    Histo1DPtr _h[10];
    /// @}


  };


  RIVET_DECLARE_PLUGIN(BESIII_2022_I2051683);

}

Rivet analyses

Mass distributions in the decay Ds+ → K+K−π+π+π−

Source code:BESIII_2022_I2051683.cc

Mass distributions in the decay D_s⁺ → K⁺K⁻π⁺π⁺π⁻

Source code:`BESIII_2022_I2051683.cc`