Rivet analyses

Baryon spectra in e+e− collisions at 10.52 GeV

Experiment: BELLE (KEKB)

Inspire ID: 1606201

Status: VALIDATED

Authors: - Peter Richardson

References: - Phys.Rev. D97 (2018) no.7, 072005

Beams: e- e+

Beam energies: (5.3, 5.3)GeV

Run details: - e+ e- to hadrons and e+ e-

Measurement of spectra for hyperon and charm baryon production in e+e− collisions at 10.52 GeV by BELLE. The spectra for Λ0, Σ0, Σ*+, Λ0(1520), Ξ−, Ω− and Ξ*0 hyperons are measured. The spectra for the Λc+, Λc(2595)+, Λc(2625)+, Σc(2455)0, Σc(2520)0, Ωc0 and Ξc0 charm baryons are also measured.

Source code:BELLE_2017_I1606201.cc

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

namespace Rivet {


  /// @brief baryon rates and spectra
  class BELLE_2017_I1606201 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(BELLE_2017_I1606201);


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

    /// Book histograms and initialise projections before the run
    void init() {
      // Initialise and register projections
      declare(UnstableParticles(), "UFS");
      // Book histograms
      for(unsigned int ix=1;ix<16;++ix) {
    book(_h[ix], ix, 1,  1);
    book(_r[ix], 16, 1, ix);
      }
    }


    /// Perform the per-event analysis
    void analyze(const Event& event) {
      const UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");

      for (const Particle& p : ufs.particles()) {
    const Vector3 mom3 = p.p3();
    double pp = mom3.mod();
    double xp = pp/sqrt(0.25*sqr(sqrtS())-sqr(p.mass()));
    int id = abs(p.pid());
    if(id==3122) {
      _h[ 1]->fill(xp);
      _r[ 1]->fill(0.5);
    }
    else if(id==3212) {
      _h[ 2]->fill(xp);
      _r[ 2]->fill(0.5);
    }
    else if(id==3224) {
      _h[ 3]->fill(xp);
      _r[ 3]->fill(0.5);
    }
    else if(id==102134) {
      _h[ 4]->fill(xp);
      _r[ 4]->fill(0.5);
    }
    else if(id==3312) {
      _h[ 5]->fill(xp);
      _r[ 5]->fill(0.5);
    }
    else if(id==3334) {
      _h[ 6]->fill(xp);
      _r[ 6]->fill(0.5);
    }
    else if(id==3324) {
      _h[ 7]->fill(xp);
      _r[ 7]->fill(0.5);
    }
    else if(id==4122) {
      _h[ 8]->fill(xp);
      _r[ 8]->fill(0.5);
    }
    else if(id==102142) {
      _h[ 9]->fill(xp);
      _r[ 9]->fill(0.5);
    }
    else if(id==102144) {
      _h[10]->fill(xp);
      _r[10]->fill(0.5);
    }
    else if(id==4112) {
      _h[11]->fill(xp);
      _r[11]->fill(0.5);
    }
    else if(id==4114) {
      _h[12]->fill(xp);
      _r[12]->fill(0.5);
    }
    else if(id==4332) {
      if(isDecay(p,{3334,-211})) {
        _h[13]->fill(xp);
        _r[13]->fill(0.5);
      }
    }
    else if(id==4132) {
      if(isDecay(p,{3312,211})) {
        _h[14]->fill(xp);
        _r[14]->fill(0.5);
      }
      else if(isDecay(p,{3334,321})) {
        _h[15]->fill(xp);
        _r[15]->fill(0.5);
      }
    }
      }
    }

    // Check for explicit decay into pdgids
    bool isDecay(const Particle& mother, vector<int> ids) {
      if(mother.pid()<0) {
    for(unsigned int ix=0;ix<ids.size();++ix)
      ids[ix] *= -1;
      }
      // Trivial check to ignore any other decays but the one in question modulo photons
      const Particles children = mother.children(Cuts::pid!=PID::PHOTON);
      if (children.size()!=ids.size()) return false;
      // Check for the explicit decay
      return all(ids, [&](int i){return count(children, hasPID(i))==1;});
    }

    /// Normalise histograms etc., after the run
    void finalize() {
      // norm to cross section
      for(unsigned int ix=1;ix<16;++ix) {
    if( ix<=4 || (ix>=8 &&ix<=12) )
      scale(_h[ix], crossSection()/nanobarn/sumOfWeights());
    else
      scale(_h[ix], crossSection()/picobarn/sumOfWeights());
    scale(_r[ix], crossSection()/picobarn/sumOfWeights());
      }
    }

    /// @}


    /// @name Histograms
    /// @{
    Histo1DPtr _h[16],_r[16];
    /// @}


  };


  RIVET_DECLARE_PLUGIN(BELLE_2017_I1606201);


}