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BABAR_2001_I558091

Inclusive $J/\psi$ cross section at 10.57 GeV
Experiment: BABAR (PEP-II)
Inspire ID: 558091
Status: VALIDATED
Authors:
  • Your Name
References:
  • PRL 87,162002
Beams: e- e+
Beam energies: ANY
Run details:
  • e+ e- to hadrons

Measurement of inclusive $J/psi$ production by BaBar for 10.57 GeV.

Source code: BABAR_2001_I558091.cc
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// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {


  /// @brief J/psi rate
  class BABAR_2001_I558091 : public Analysis {
  public:

    /// Constructor
    DEFAULT_RIVET_ANALYSIS_CTOR(BABAR_2001_I558091);


    /// @name Analysis methods
    //@{

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


    /// Perform the per-event analysis
    void analyze(const Event& event) {
      const UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");
      double nJsi=0.;
      for (const Particle& p : ufs.particles()) {
        if (p.pid()==443) {
	  bool fs = true;
	  for (const Particle & child : p.children()) {
	    if(child.pid()==443) {
	      fs = false;
	      break;
	    }
	  }
	  if(fs) nJsi += 1.;
	}
      }
      _c_jpsi->fill(nJsi);
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      double fact = crossSection()/ sumOfWeights() /picobarn;
      double sigma = _c_jpsi->val()*fact;
      double error = _c_jpsi->err()*fact;
      Scatter2D temphisto(refData(1, 1, 1));
      Scatter2DPtr mult;
      book(mult, 1, 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 _c_jpsi;
    //@}


  };


  // The hook for the plugin system
  DECLARE_RIVET_PLUGIN(BABAR_2001_I558091);


}