Rivet analyses

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

namespace Rivet {


  /// @brief Delta++ rate and spectrum
  class ARGUS_1989_I278932 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(ARGUS_1989_I278932);


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

    /// Book histograms and initialise projections before the run
    void init() {
      // Initialise and register projections
      declare(UnstableParticles(), "UFS");
      // histograms
      book(_r_ups, 1, 1, 2);
      book(_r_cont, 2, 1, 2);
      book(_h_p, 3, 1, 1);
      book(_w_ups, "TMP/w_ups");
      book(_w_cont, "TMP/w_cont");
    }


    /// Recursively walk the decay tree to find decay products of @a p
    void findDecayProducts(Particle mother, Particles& delta) {
      // dleta pdg code
      static const long id = 2224;
      for (const Particle& p : mother.children()) {
        if (p.abspid() == id) {
          delta.push_back(p);
        }
        else if (!p.children().empty()) {
          findDecayProducts(p, delta);
        }
      }
    }

    /// Perform the per-event analysis
    void analyze(const Event& event) {
      UnstableParticles ufs = apply<UnstableParticles>(event, "UFS");
      Particles ups = ufs.particles(Cuts::pid == 553);
      // continuum
      if (ups.empty()) {
        _w_cont->fill();
        _r_cont->fill(Ecm2, ufs.particles(Cuts::abspid == 2224).size());
      }
      // upsilon decays
      else {
        for (const Particle& p : ups) {
          _w_ups->fill();
          Particles delta;
          findDecayProducts(p, delta);
          if (delta.empty()) continue;
          LorentzTransform boost;
          if (p.p3().mod() > 1 * MeV) {
            boost = LorentzTransform::mkFrameTransformFromBeta(p.momentum().betaVec());
          }
          for (const Particle& del : delta) {
            _r_ups->fill(Ecm1);
            double mom = boost.transform(del.momentum()).p3().mod();
            _h_p->fill(mom);
          }
        }
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      if (_w_cont->effNumEntries() > 0) {
        scale(_r_cont, 1. / *_w_cont);
      }
      // direct upsilon decays, i.e. to gg gamma and ggg so need to renormalize
      // factor and values from arxiv:0612019
      if (_w_ups->effNumEntries() > 0) {
        const double Bmumu = 0.0249, rhad = 3.56;
        const double fact = 1. - (3. + rhad) * Bmumu;
        scale(_r_ups, 1. / fact / *_w_ups);
        scale(_h_p, 100. / fact / *_w_ups);
      }
    }

    /// @}


    /// @name Histograms
    /// @{
    BinnedHistoPtr<string> _r_ups, _r_cont;
    Histo1DPtr _h_p;
    CounterPtr _w_ups, _w_cont;
    const string Ecm1 = "9.46", Ecm2 = "10.2";
    /// @}
  };


  RIVET_DECLARE_PLUGIN(ARGUS_1989_I278932);

}