Rivet analyses

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

namespace Rivet {


  /// @brief anti-deuteron spectrum in upslion decays
  class BABAR_2014_I1286317 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(BABAR_2014_I1286317);


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

    /// Book histograms and initialise projections before the run
    void init() {
      // Initialise and register projections
      declare(UnstableParticles(), "UFS");
      // histograms
      book(_h_p[0], 6, 1, 1);
      book(_h_p[1], 6, 2, 1);
      book(_h_p[2], 6, 3, 1);
      book(_h_p[3], 6, 4, 1);
      book(_h_r[0], 1, 1, 1);
      book(_h_r[1], 2, 1, 1);
      book(_h_r[2], 3, 1, 1);
      book(_h_r[3], 5, 1, 1);
      book(_h_r[4], 4, 1, 1);
      book(_w[0], "TMP/w_0");
      book(_w[1], "TMP/w_1");
      book(_w[2], "TMP/w_2");
      book(_w[3], "TMP/w_3");
    }

    /// Recursively walk the decay tree to find decay products of @a p
    void findDecayProducts(Particle mother, Particles& deut) {
      for (const Particle& p : mother.children()) {
        if (p.pid() == _did) {
          deut.push_back(p);
        }
        else if (!p.children().empty())
          findDecayProducts(p, deut);
      }
    }

    /// Perform the per-event analysis
    void analyze(const Event& event) {
      // find upsilon states
      UnstableParticles ufs = apply<UnstableParticles>(event, "UFS");
      Particles ups = ufs.particles(Cuts::pid == 553 || Cuts::pid == 100553 || Cuts::pid == 200553);
      // none, then continuum event
      if (ups.empty()) {
        Particles deut = ufs.particles(Cuts::pid == _did);
        _w[3]->fill();
        for (const Particle& p : deut) {
          double mom = p.momentum().p3().mod();
          _h_p[3]->fill(mom);
          _h_r[3]->fill("10.58"s);
          _h_r[4]->fill("10.58"s);
        }
      }
      // upsilon decays
      else {
        for (const Particle& Y : ups) {
          unsigned int ihist = 2;
          if (Y.pid() == 100553) {
            ihist = 1;
          }
          else if (Y.pid() == 200553) {
            ihist = 0;
          }
          _w[ihist]->fill();
          Particles deut;
          findDecayProducts(Y, deut);
          if (deut.empty()) continue;
          LorentzTransform boost;
          if (Y.p3().mod() > 1 * MeV)
            boost = LorentzTransform::mkFrameTransformFromBeta(Y.momentum().betaVec());
          for (const Particle& p : deut) {
            double mom = boost.transform(p.momentum()).p3().mod();
            _h_r[ihist]->fill("10.58"s);
            _h_p[ihist]->fill(mom);
            _w[ihist]->fill();
          }
        }
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      // upsilon decays
      for (unsigned int ix = 0; ix < 3; ++ix) {
        if (_w[ix]->effNumEntries() <= 0.) continue;
        scale(_h_p[ix], 1e6 / *_w[ix]);
        scale(_h_r[ix], 1. / *_w[ix]);
        Histo1DPtr _h_p[4], _h_r[5];
        CounterPtr _w[4];
      }
      // continuum
      if (_w[3]->effNumEntries() > 0.) {
        scale(_h_p[3], crossSection() / sumOfWeights() / femtobarn);
        scale(_h_r[4], crossSection() / sumOfWeights() / femtobarn);
        scale(_h_r[3], 1. / *_w[3]);
      }
    }

    /// @}


    /// @name Histograms
    /// @{
    Histo1DPtr _h_p[4];
    BinnedHistoPtr<string> _h_r[5];
    CounterPtr _w[4];

    // deuteron id code
    static const int _did = -1000010020;
    /// @}
  };


  RIVET_DECLARE_PLUGIN(BABAR_2014_I1286317);

}