Rivet analyses

Measurement of R and D* production for energies between 3.67 and 4.5 GeV.

Experiment: CRYSTAL_BALL (Spear)

Inspire ID: 238081

Status: VALIDATED

Authors: - Peter Richardson

References: - https://doi.org/10.17182/hepdata.18759

Beams: e- e+

Beam energies: ANY

Run details: - e+ e- to hadrons and e+ e- to mu+ mu- (for normalization)

Measurement of R in e+e− collisions by the Crystal Ball experiment for energies between 3.67 and 4.5 GeV. The cross section for D* production is also measured. The individual hadronic and muonic cross sections are also outputted to the yoda file so that ratio R can be recalcuated if runs are combined.

Source code:CRYSTAL_BALL_1986_I238081.cc

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

namespace Rivet {


  /// @brief e+e- > hadrons
  class CRYSTAL_BALL_1986_I238081 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(CRYSTAL_BALL_1986_I238081);


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

    /// Book histograms and initialise projections before the run
    void init() {
      // Initialise and register projections
      declare(FinalState(), "FS");
      declare(UnstableParticles(), "UFS");

      // Book histograms
      book(_c_hadrons, "/TMP/sigma_hadrons", refData<YODA::BinnedEstimate<string>>(1, 1, 1));
      book(_c_muons, "/TMP/sigma_muons", refData<YODA::BinnedEstimate<string>>(1, 1, 1));
      book(_c_D_star, "/TMP/sigma_D_star", refData(2, 1, 1));

      for (const string& en : _c_hadrons.binning().edges<0>()) {
        if (isCompatibleWithSqrtS(stod(en) * GeV, 1e-3)) {
          _sqs = en;
          break;
        }
      }
      raiseBeamErrorIf(_sqs.empty() and !inRange(sqrtS() / GeV, 3.87, 4.5));
    }


    /// Perform the per-event analysis
    void analyze(const Event& event) {
      const FinalState& fs = apply<FinalState>(event, "FS");

      map<long, int> nCount;
      int ntotal(0);
      for (const Particle& p : fs.particles()) {
        nCount[p.pid()] += 1;
        ++ntotal;
      }
      if (nCount[-13] == 1 && nCount[13] == 1 && ntotal == 2 + nCount[22]) {
        // mu+mu- + photons
        _c_muons->fill(_sqs);
      }
      else
        _c_hadrons->fill(_sqs); // everything else
      const FinalState& ufs = apply<UnstableParticles>(event, "UFS");
      bool found = false;
      for (const Particle& p : ufs.particles()) {
        if (p.abspid() != 413 && p.abspid() != 423) continue;
        bool fs = true;
        for (const Particle& child : p.children()) {
          if (child.pid() == p.pid()) {
            fs = false;
            break;
          }
        }
        if (fs) {
          found = true;
          break;
        }
      }
      if (found) _c_D_star->fill(sqrtS());
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      // R
      BinnedEstimatePtr<string> tmp;
      book(tmp, 1, 1, 1);
      divide(_c_hadrons, _c_muons, tmp);
      double fact = crossSection() / sumOfWeights() / nanobarn;
      scale(_c_D_star, fact);
      Estimate1DPtr tmp2;
      book(tmp2, 2, 1, 1);
      barchart(_c_D_star, tmp2);
    }

    /// @}


    /// @name Histograms
    /// @{
    BinnedHistoPtr<string> _c_hadrons, _c_muons;
    Histo1DPtr _c_D_star;
    string _sqs = "";
    /// @}
  };


  RIVET_DECLARE_PLUGIN(CRYSTAL_BALL_1986_I238081);
}