Rivet analyses

Cross section for e+e− → Υ(1, 2S) → μ+μ−

Experiment: CRYSTAL_BALL (DORIS)

Inspire ID: 306832

Status: VALIDATED

Authors: - Peter Richardson

References: - Z.Phys.C 53 (1992) 193-206

Beams: e+ e-

Beam energies: ANY

Run details: - e+e- > Upslion(1,2S) -> mu+mu-

Cross section for e+e− → Υ(1, 2S) → μ+μ−. The continuum contribution was subtracted. As the analyses requires the beam energy smearing described in the paper then central CMS energy should be specified using the ECENT (in MeV) option..

Source code:CRYSTAL_BALL_1992_I306832.cc

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

namespace Rivet {


  /// @brief e+e- to Upsilon to mu+mu-
  class CRYSTAL_BALL_1992_I306832 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(CRYSTAL_BALL_1992_I306832);


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

    /// Book histograms and initialise projections before the run
    void init() {
      // Initialise and register projections
      declare(Beam(), "Beams");
      declare(FinalState(), "FS");
      // histograms
      for(unsigned int ix=0;ix<2;++ix)
        book(_c[ix], 1+ix, 1, 1);
      _eCent = getOption<string>("ECENT", std::to_string(sqrtS()/MeV));
    }


    /// Perform the per-event analysis
    void analyze(const Event& event) {
      // loop over FS particles
      Particles fs = apply<FinalState>(event,"FS").particles();
      Particles mm,mp;
      for (const Particle& p : fs) {
        if (p.abspid()==PID::MUON) {
          if (p.pid()>0) mm.push_back(p);
          else           mp.push_back(p);
        }
        else if(p.pid()!=PID::GAMMA) {
          vetoEvent;
        }
      }
      if (mm.size()==1 && mp.size()==1) {
        _c[0]->fill(_eCent);
        _c[1]->fill(_eCent);
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      double fact = crossSection()/ sumOfWeights() /picobarn;
      for (unsigned int ix=0; ix<2; ++ix)
        scale(_c[ix],fact);
    }

    /// @}


    /// @name Histograms
    /// @{
    BinnedHistoPtr<string> _c[2];
    string _eCent;
    /// @}


  };


  RIVET_DECLARE_PLUGIN(CRYSTAL_BALL_1992_I306832);

}