Rivet analyses

Cross section for e+e−→ proton and antiproton between 2 and 3.07 GeV

Experiment: BESII (BEPC)

Inspire ID: 685906

Status: VALIDATED

Authors: - Peter Richardson

References: - Phys.Rev. D91 (2015) 112004, 2015

Beams: e+ e-

Beam energies: (1.0, 1.0); (1.1, 1.1); (1.2, 1.2); (1.2, 1.2); (1.3, 1.3); (1.4, 1.4); (1.4, 1.4); (1.5, 1.5); (1.5, 1.5)GeV

Run details: - e+ e- to hadrons

Measurement of the cross section for e+e− → pp̄ for energies between 2 and 3.07 GeV.

Source code:BESII_2005_I685906.cc

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

namespace Rivet {


  /// @brief Cross section for e+e- to proton and antiproton between 2 and 3.07 GeV
  class BESII_2005_I685906 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(BESII_2005_I685906);


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

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

      // Initialise and register projections
      declare(FinalState(), "FS");

      // Book histograms
      book(_nproton, 1, 1, 1);
      for (const string& en : _nproton.binning().edges<0>()) {
        const double eval = std::stod(en);
        if (isCompatibleWithSqrtS(eval)) {
          _sqs = en; break;
        }
      }
      raiseBeamErrorIf(_sqs.empty());
    }


    /// Perform the per-event analysis
    void analyze(const Event& event) {
      const FinalState& fs = apply<FinalState>(event, "FS");
      if (fs.particles().size()!=2) vetoEvent;
      for (const Particle& p : fs.particles()) {
        if (p.abspid() != PID::PROTON) vetoEvent;
      }
      _nproton->fill(_sqs);
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      scale(_nproton, crossSection()/ sumOfWeights() /picobarn);
    }

    /// @}


    /// @name Histograms
    /// @{
    BinnedHistoPtr<string> _nproton;
    string _sqs = "";
    /// @}


  };


  RIVET_DECLARE_PLUGIN(BESII_2005_I685906);

}