Rivet analyses

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

namespace Rivet {


  /// @brief B -> c l nu moments
  class CLEOII_2004_I647287 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(CLEOII_2004_I647287);


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

    /// Book histograms and initialise projections before the run
    void init() {
      // projections
      declare(UnstableParticles(Cuts::abspid == 511 || Cuts::abspid == 521), "UFS");
      // spin weighted average D and D* mass
      _mD2 = sqr(0.125 * (1.86966 + 1.86484) + 0.375 * (2.00685 + 2.01026));
      // histograms
      for (unsigned int ix = 0; ix < 2; ++ix) {
        for (unsigned int iy = 0; iy < 4; ++iy) {
          if (iy % 2 == 1) {
            book(_p[ix][iy], "TMP/p_" + toString(ix) + "_" + toString(iy),
                 refData<YODA::BinnedEstimate<string>>(1, 1 + iy, 1 + ix));
          }
          else {
            book(_p[ix][iy], 1, +1 + iy, 1 + ix);
          }
        }
      }
      book(_p_dist, 2, 1, 1);
    }

    void findDecayProducts(const Particle& parent,
                           Particles& em,
                           Particles& ep,
                           Particles& nue,
                           Particles& nueBar,
                           bool& charm) {
      for (const Particle& p : parent.children()) {
        if (PID::isCharmHadron(p.pid())) {
          charm = true;
        }
        else if (p.pid() == PID::EMINUS || p.pid() == PID::MUON) {
          em.push_back(p);
        }
        else if (p.pid() == PID::EPLUS || p.pid() == PID::ANTIMUON) {
          ep.push_back(p);
        }
        else if (p.pid() == PID::NU_E || p.pid() == PID::NU_MU) {
          nue.push_back(p);
        }
        else if (p.pid() == PID::NU_EBAR || p.pid() == PID::NU_MUBAR) {
          nueBar.push_back(p);
        }
        else if (PID::isBottomHadron(p.pid())) {
          findDecayProducts(p, em, ep, nue, nueBar, charm);
        }
        else if (!PID::isHadron(p.pid())) {
          findDecayProducts(p, em, ep, nue, nueBar, charm);
        }
      }
    }

    /// Perform the per-event analysis
    void analyze(const Event& event) {
      if (_edges.empty()) _edges = _p_dist->xEdges();
      const double Ecut[2] = {1., 1.5};
      // find and loop over Upslion(4S)
      for (const Particle& p : apply<UnstableParticles>(event, "UFS").particles()) {
        if (p.children().empty() || (p.children().size() == 1 && p.children()[1].abspid() == p.abspid())) {
          continue;
        }
        // find decay products
        bool charm = false;
        Particles em, ep, nue, nueBar;
        findDecayProducts(p, em, ep, nue, nueBar, charm);
        if (!charm) continue;
        FourMomentum pl, pnu;
        if (em.size() == 1 && nueBar.size() == 1 && em[0].pid() + 1 == -nueBar[0].pid()) {
          pl = em[0].mom();
          pnu = nueBar[0].mom();
        }
        else if (ep.size() == 1 && nue.size() == 1 && nue[0].pid() == -ep[0].pid() + 1) {
          pl = ep[0].mom();
          pnu = nue[0].mom();
        }
        else {
          continue;
        }
        // boost to rest frame
        LorentzTransform boost = LorentzTransform::mkFrameTransformFromBeta(p.mom().betaVec());
        double q2 = (pl + pnu).mass2();
        FourMomentum pX = boost.transform(p.mom() - pl - pnu);
        pl = boost.transform(pl);
        double mX2 = pX.mass2();
        for (unsigned int ix = 0; ix < 2; ++ix) {
          if (pl.E() > Ecut[ix]) {
            _p[ix][0]->fill(_edges[5 * ix], mX2 - _mD2);
            _p[ix][1]->fill(_edges[5 * ix], sqr(mX2));
            _p[ix][2]->fill(_edges[5 * ix], q2);
            _p[ix][3]->fill(_edges[5 * ix], sqr(q2));
          }
        }
        for (unsigned int ix = 0; ix < 6; ++ix) {
          if (1. + 0.1 * ix < pl.E()) _p_dist->fill(_edges[ix], mX2 - _mD2);
        }
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      for (unsigned int ix = 0; ix < 2; ++ix) {
        // compute <(mx2-<mx2>)^2> = <mx4>-<mx2>^2
        BinnedEstimatePtr<string> tmp;
        book(tmp, 1, 2, 1 + ix);
        for (const auto& b0 : _p[ix][0]->bins()) {
          const auto& b1 = _p[ix][1]->bin(b0.index());
          const double val = b1.yMean() - sqr(b0.yMean() + _mD2);
          const double err = val * sqrt(sqr(b1.relErrW()) + 4. * sqr(b0.yStdErr() / (b0.yMean() + _mD2)));
          tmp->bin(b0.index()).set(val, err);
        }
        // compute <(q2-<q2>)^2> = <q4>-<q2>^2
        book(tmp, 1, 4, 1 + ix);
        for (const auto& b2 : _p[ix][2]->bins()) {
          const auto& b3 = _p[ix][3]->bin(b2.index());
          const double val = b3.yMean() - sqr(b2.yMean());
          const double err = val * sqrt(sqr(b3.relErrW()) + 4. * sqr(b3.relErrW()));
          tmp->bin(b2.index()).set(val, err);
        }
      }
    }

    /// @}


    /// @name Histograms
    /// @{
    BinnedProfilePtr<string> _p[2][4], _p_dist;
    vector<string> _edges;
    double _mD2;
    /// @}
  };


  RIVET_DECLARE_PLUGIN(CLEOII_2004_I647287);

}