Rivet analyses

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

namespace Rivet {


  /// @brief B_s0 at 5.02 TeV
  class CMS_2019_I1697571 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(CMS_2019_I1697571);


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

    /// Book histograms and initialise projections before the run
    void init() {
      // projection
      declare(UnstableParticles(), "UFS");
      // histograms
      book(_h_pT[0],1,1,1);
      book(_h_pT[1],2,1,1);

      _axes[0] = YODA::Axis<double>({7.,15.,20.,50.});
      _axes[1] = YODA::Axis<double>({7.,15.,50.});
    }


    /// Perform the per-event analysis
    void analyze(const Event& event) {
      if (_edges[0].empty()) {
        _edges[0] = _h_pT[0]->xEdges();
        _edges[1] = _h_pT[1]->xEdges();
      }
      // Final state of unstable particles to get particle spectra
      const UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");
      // loop over onium states
      for (const Particle& p : ufs.particles(Cuts::abspid==531)) {
        // skip copies due mixing
        if (p.children().size()==1 && p.children()[0].abspid()==531) continue;
        // rapidity and pT
        const double y = p.absrap();
        if (y>2.4) continue;
        const double pT = p.perp();
        if (pT<7. || pT>50.) continue;
        for (unsigned int ix=0; ix<2; ++ix) {
          const size_t idx = _axes[ix].index(pT);
          string edge("OTHER");
          if (idx && idx <= _edges[ix].size()) edge = _edges[ix][idx-1];
          _h_pT[ix]->fill(edge);
        }
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      // 0.5 from particle/antiparticle
      double fact = 0.5*crossSection()/picobarn/sumOfWeights();
      for (unsigned int ix=0; ix<2; ++ix) {
        scale(_h_pT[ix], fact);
        for (auto& b : _h_pT[ix]->bins()) {
          b.scaleW( 1.0/_axes[ix].width(b.index()) );
        }
      }
    }

    /// @}


    /// @name Histograms
    /// @{
    BinnedHistoPtr<string> _h_pT[2];
    YODA::Axis<double> _axes[2];
    vector<string> _edges[2];
    /// @}


  };


  RIVET_DECLARE_PLUGIN(CMS_2019_I1697571);

}