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BABAR_2006_I709730

Cross section for $e^+e^-\to$ $3\pi^+3\pi^-$, $2\pi^+2\pi^-2\pi^0$, $2\pi^+2\pi^-K^+K^-$
Experiment: BABAR (PEP-II)
Inspire ID: 709730
Status: VALIDATED
Authors:
  • Peter Richardson
References:
  • Phys.Rev. D73.052003
Beams: e+ e-
Beam energies: ANY
Run details:
  • e+ e- to hadrons

Cross sections for $3\pi^+3\pi^-$, $2\pi^+2\pi^-2\pi^0$ and $2\pi^+2\pi^-K^+K^-$ measured by BaBar using radiative return. Useful to compare hadronization and other non-perturbative models at low energies between 1.3 and 4.5 GeV.

Source code: BABAR_2006_I709730.cc
  1// -*- C++ -*-
  2#include "Rivet/Analysis.hh"
  3#include "Rivet/Projections/FinalState.hh"
  4
  5
  6namespace Rivet {
  7
  8
  9  /// @brief e+e- -> 3pi+3pi-, 2pi+pi-2pi0, 2pi+pi-K+K-
 10  class BABAR_2006_I709730 : public Analysis {
 11  public:
 12
 13    /// Constructor
 14    RIVET_DEFAULT_ANALYSIS_CTOR(BABAR_2006_I709730);
 15
 16
 17    /// @name Analysis methods
 18    //@{
 19
 20    /// Book histograms and initialise projections before the run
 21    void init() {
 22
 23      // Initialise and register projections
 24      declare(FinalState(), "FS");
 25      book(_num3pip3pim,      "TMP/num3pip3pim"     );
 26      book(_num2pip2pim2pi0,  "TMP/num2pip2pim2pi0" );
 27      book(_num2pip2pim2KpKm, "TMP/num2pip2pim2KpKm");
 28    }
 29
 30
 31    /// Perform the per-event analysis
 32    void analyze(const Event& event) {
 33      const FinalState& fs = apply<FinalState>(event, "FS");
 34
 35      map<long,int> nCount;
 36      int ntotal(0);
 37      for (const Particle& p : fs.particles()) {
 38	nCount[p.pid()] += 1;
 39	++ntotal;
 40      }
 41
 42      if(ntotal!=6) vetoEvent;
 43      if(nCount[-211]==3 && nCount[211]==3)
 44	_num3pip3pim->fill();
 45      else if(nCount[-211]==2 && nCount[211]==2 && nCount[111]==2)
 46	_num2pip2pim2pi0->fill();
 47      else if(nCount[-211]==2 && nCount[211]==2 && nCount[321]==1 && nCount[-321]==1)
 48	_num2pip2pim2KpKm->fill();
 49    }
 50
 51
 52    /// Normalise histograms etc., after the run
 53    void finalize() {
 54
 55      for(unsigned int ix=1; ix<4; ++ix) {
 56        double sigma = 0., error = 0.;
 57        if(ix==1) {
 58          sigma = _num3pip3pim->val();
 59          error = _num3pip3pim->err();
 60        }
 61        else if(ix==2) {
 62          sigma = _num2pip2pim2pi0->val();
 63          error = _num2pip2pim2pi0->err();
 64        }
 65        else if(ix==3) {
 66          sigma = _num2pip2pim2KpKm->val();
 67          error = _num2pip2pim2KpKm->err();
 68        }
 69        sigma *= crossSection()/ sumOfWeights() /nanobarn;
 70        error *= crossSection()/ sumOfWeights() /nanobarn;
 71        Scatter2D temphisto(refData(ix, 1, 1));
 72        Scatter2DPtr mult;
 73        book(mult, ix, 1, 1);
 74        for (size_t b = 0; b < temphisto.numPoints(); b++) {
 75          const double x  = temphisto.point(b).x();
 76          pair<double,double> ex = temphisto.point(b).xErrs();
 77          pair<double,double> ex2 = ex;
 78          if(ex2.first ==0.) ex2. first=0.0001;
 79          if(ex2.second==0.) ex2.second=0.0001;
 80          if (inRange(sqrtS()/GeV, x-ex2.first, x+ex2.second)) {
 81            mult->addPoint(x, sigma, ex, make_pair(error,error));
 82          }
 83          else {
 84            mult->addPoint(x, 0., ex, make_pair(0.,.0));
 85          }
 86        }
 87      }
 88    }
 89
 90    //@}
 91
 92    // just count the number of events of the types we're looking for
 93    CounterPtr _num3pip3pim,_num2pip2pim2pi0,_num2pip2pim2KpKm;
 94    
 95  };
 96
 97
 98  // The hook for the plugin system
 99  RIVET_DECLARE_PLUGIN(BABAR_2006_I709730);
100
101
102}