Rivet analyses

Cross section for e⁺e⁻ → Jψπ⁺π⁻ at energies between 3.8 and 5.5 GeV

Experiment: BELLE (KEKB)

Inspire ID: 756012

Status: VALIDATED

Authors: - Peter Richardson

References: - Phys.Rev.Lett. 99 (2007) 182004, 2007

Beams: e+ e-

Beam energies: ANY

Run details: - e+e- to hadrons

Measurement of the cross section for e⁺e⁻ → Jψπ⁺π⁻ at energies between 3.8 and 5.5 GeV using radiative return by BELLE.

Source code:`BELLE_2007_I756012.cc`

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

namespace Rivet {


  /// @brief Add a short analysis description here
  class BELLE_2007_I756012 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(BELLE_2007_I756012);


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

    /// Book histograms and initialise projections before the run
    void init() {
      declare(FinalState(), "FS");
      declare(UnstableParticles(), "UFS");
      book(_nJPsi, "TMP/jpsi");
    }

    void findChildren(const Particle & p,map<long,int> & nRes, int &ncount) {
      for (const Particle &child : p.children()) {
    if(child.children().empty()) {
      --nRes[child.pid()];
      --ncount;
    }
    else
      findChildren(child,nRes,ncount);
      }
    }

    /// Perform the per-event analysis
    void analyze(const Event& event) {
      const FinalState& fs = apply<FinalState>(event, "FS");
      map<long,int> nCount;
      int ntotal(0);
      for (const Particle& p : fs.particles()) {
    nCount[p.pid()] += 1;
    ++ntotal;
      }
      const FinalState& ufs = apply<FinalState>(event, "UFS");
      for (const Particle& p : ufs.particles()) {
    if(p.children().empty()) continue;
    if(p.pid()!=443) continue;
    // find the J/psi
    map<long,int> nRes = nCount;
    int ncount = ntotal;
    findChildren(p,nRes,ncount);
    // J/psi pi+pi-
    if(ncount!=2) continue;
    bool matched = true;
    for(auto const & val : nRes) {
      if(abs(val.first)==211) {
        if(val.second !=1) {
          matched = false;
          break;
        }
      }
      else if(val.second!=0) {
        matched = false;
        break;
      }
    }
    if(matched) {
      _nJPsi->fill();
      break;
    }
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      double sigma =  _nJPsi->val();
      double error = _nJPsi->err();
      sigma *= crossSection()/ sumOfWeights() /picobarn;
      error *= crossSection()/ sumOfWeights() /picobarn;
      Estimate1DPtr  mult;
      book(mult, 1, 1, 1);
      for (auto& b : mult->bins()) {
        if (inRange(sqrtS()/GeV, b.xMin(), b.xMax())) {
          b.set(sigma, error);
        }
      }
    }

    /// @}


    /// @name Histograms
    /// @{
    CounterPtr _nJPsi;
    /// @}


  };


  RIVET_DECLARE_PLUGIN(BELLE_2007_I756012);


}

Rivet analyses

Cross section for e+e− → Jψπ+π− at energies between 3.8 and 5.5 GeV

Source code:BELLE_2007_I756012.cc

Cross section for e⁺e⁻ → Jψπ⁺π⁻ at energies between 3.8 and 5.5 GeV

Source code:`BELLE_2007_I756012.cc`