Rivet Analyses Reference

BELLE_2009_I809630

Cross Section for $e^+e^-\to\phi\pi^+\pi^-$ between 1.488 and 2.987 GeV
Experiment: BELLE (KEKB)
Inspire ID: 809630
Status: VALIDATED
Authors:
  • Peter Richardson
References:
  • Phys.Rev. D80 (2009) 031101, 2009
Beams: e+ e-
Beam energies: ANY
Run details:
  • e+e- to hadrons

Measurement of the cross section for $e^+e^-\to\phi\pi^+\pi^-$ between 1.488 and 2.987 GeV

Source code: BELLE_2009_I809630.cc
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// -*- 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_2009_I809630 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(BELLE_2009_I809630);


    /// @name Analysis methods
    //@{

    /// Book histograms and initialise projections before the run
    void init() {

      // Initialise and register projections
      declare(FinalState(), "FS");
      declare(UnstableParticles(), "UFS");
      book(_cphipippim, "TMP/phipippim");
      book(_cphif0 ,    "TMP/phif0");
    }

    void findChildren(const Particle & p,map<long,int> & nRes, int &ncount) {
      for(const Particle &child : p.children()) {
	if(child.children().empty()) {
	  nRes[child.pid()]-=1;
	  --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;
	// phi
	if(p.pid()!=333) continue;
	map<long,int> nRes=nCount;
	int ncount = ntotal;
	findChildren(p,nRes,ncount);
	// phi pi+pi-
	if(ncount==2) {
	  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)
	    _cphipippim->fill();
	}
	for (const Particle& p2 : ufs.particles()) {
	  if(p2.pid()!=9010221) continue;
	  if(p2.parents()[0].isSame(p)) continue;
	  map<long,int> nResB = nRes;
	  int ncountB = ncount;
	  findChildren(p2,nResB,ncountB);
	  if(ncountB!=0) continue;
	  bool matched2 = true;
	  for(auto const & val : nResB) {
	    if(val.second!=0) {
	      matched2 = false;
	      break;
	    }
	  }
	  if(matched2) {
	    _cphif0  ->fill();
	  }
	}
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      for(unsigned int ix=1;ix<3;++ix) {
	double sigma,error;
	if(ix==1) {
	  sigma = _cphipippim->val();
	  error = _cphipippim->err();
	}
	else {
	  sigma = _cphif0->val();
	  error = _cphif0->err();
	}
	sigma *= crossSection()/ sumOfWeights() /nanobarn;
	error *= crossSection()/ sumOfWeights() /nanobarn;
	Scatter2D temphisto(refData(ix, 1, 1));
	Scatter2DPtr  mult;
        book(mult, ix, 1, 1);
	for (size_t b = 0; b < temphisto.numPoints(); b++) {
	  const double x  = temphisto.point(b).x();
	  pair<double,double> ex = temphisto.point(b).xErrs();
	  pair<double,double> ex2 = ex;
	  if(ex2.first ==0.) ex2. first=0.0001;
	  if(ex2.second==0.) ex2.second=0.0001;
	  if (inRange(sqrtS()/GeV, x-ex2.first, x+ex2.second)) {
	    mult->addPoint(x, sigma, ex, make_pair(error,error));
	  }
	  else {
	    mult->addPoint(x, 0., ex, make_pair(0.,.0));
	  }
	}
      }
    }
    //@}


    /// @name Histograms
    //@{
    CounterPtr _cphipippim;
    CounterPtr _cphif0;
    //@}


  };


  // The hook for the plugin system
  RIVET_DECLARE_PLUGIN(BELLE_2009_I809630);


}