Rivet analyses

Cross section for e+e−→ proton and antiproton between 1.877 and 4.25 GeV

Experiment: BABAR (PEP-II)

Inspire ID: 1217421

Status: VALIDATED

Authors: - Peter Richardson

References: - Phys.Rev. D87 (2013) 092005, 2013

Beams: e+ e-

Beam energies: ANY

Run details: - e+ e- to hadrons

Measurement of the cross section for e+e− → pp̄ using radiative return for energies between 1.877 and 4.25 GeV.

Source code:BABAR_2013_I1217421.cc

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


namespace Rivet {


  /// @brief e+e- > p pbar
  class BABAR_2013_I1217421 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(BABAR_2013_I1217421);


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

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

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

      // Book histograms
      book(_nproton, "TMP/proton");
    }


    /// 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(abs(p.pid())!=PID::PROTON) vetoEvent;
      }
      _nproton->fill();
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      double sigma = _nproton->val();
      double error = _nproton->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 _nproton;
    /// @}


  };


  RIVET_DECLARE_PLUGIN(BABAR_2013_I1217421);


}