Rivet analyses

Cross section for e+e− → pp̄π0 at energies between 2.1 and 3.08 GeV

Experiment: BESIII (BEPC)

Inspire ID: 2785382

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Phys.Rev.D 110 (2024) 5, 052006 - arXiv: 2405.06393

Beams: e+ e-

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

Run details: - e+e- to hadrons, pi0 stable

Cross section for e+e− → pp̄π0 at energies between 2.1 and 3.08 GeV measured by the BESIII collaboration.

Source code:BESIII_2024_I2785382.cc

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

namespace Rivet {


  /// @brief Cross section for e+e- -> p pbar pi0 for energies between 2.1 and 3.08 GeV
  class BESIII_2024_I2785382 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2024_I2785382);

    /// @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 = stod(en)*GeV;
        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()!=3) vetoEvent;
      for (const Particle& p :  fs.particles()) {
        if (p.abspid() != PID::PROTON && p.pid() != PID::PI0) 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(BESIII_2024_I2785382);
}