Rivet analyses

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

namespace Rivet {


  /// @brief D spect in B decays
  class CLEOII_1997_I440969 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(CLEOII_1997_I440969);


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

    /// Book histograms and initialise projections before the run
    void init() {
      // projections
      declare(UnstableParticles(Cuts::pid == 300553), "UFS");
      // histos
      const vector<double> xbins = {0.0, 0.1, 0.2, 0.3, 0.4, 0.5};
      for (unsigned int ix = 0; ix < 4; ++ix) {
        book(_h[ix], 1 + ix, 1, 1);
      }
      book(_b[0], {0.1, 0.2, 0.3, 0.4, 0.5});
      book(_b[1], {0.0, 0.1, 0.2, 0.3, 0.4, 0.5});
      for (auto& b : _b[1]->bins()) {
        book(b, 6, 1, b.index());
        if (b.index() < 5) {
          book(_b[0]->bin(b.index()), 5, 1, b.index());
        }
      }
      for (unsigned int ix = 0; ix < 2; ++ix) {
        book(_p[ix], "TMP/p_" + toString(ix + 1), refData(7, 1, 1 + ix));
      }
    }

    void findDecay(const Particle& parent, Particles& Ds) {
      for (const Particle& p : parent.children()) {
        if (p.abspid() == 421 || p.abspid() == 411) {
          Ds.push_back(p);
        }
        else if (p.abspid() == 413 || p.abspid() == 423) {
          Ds.push_back(p);
          findDecay(p, Ds);
        }
        else if (p.abspid() == PID::PIPLUS || p.abspid() == PID::KPLUS || p.pid() == PID::PI0
                 || p.pid() == PID::K0S) {
          continue;
        }
        else if (!p.children().empty()) {
          findDecay(p, Ds);
        }
      }
    }


    /// Perform the per-event analysis
    void analyze(const Event& event) {
      const UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");
      for (const Particle& p : ufs.particles()) {
        const LorentzTransform boost = LorentzTransform::mkFrameTransformFromBeta(p.mom().betaVec());
        for (const Particle& B : p.children()) {
          if (B.abspid() != 511 && B.abspid() != 521) continue;
          Particles Ds;
          findDecay(B, Ds);
          for (const Particle& p2 : Ds) {
            FourMomentum pD = boost.transform(p2.mom());
            const double x = pD.p3().mod() / sqrt(0.25 * sqr(p.mass()) - sqr(p2.mass()));
            if (p2.abspid() == 421)
              _h[0]->fill(x);
            else if (p2.abspid() == 411)
              _h[1]->fill(x);
            else {
              // x distribution for D*
              if (p2.abspid() == 423)
                _h[2]->fill(x);
              else
                _h[3]->fill(x);
              // find decay products
              if (p2.children().size() != 2) continue;
              Particle dec;
              if ((p2.children()[0].abspid() == 411 || p2.children()[0].abspid() == 421)
                  && (p2.children()[1].abspid() == 111 || p2.children()[1].abspid() == 211)) {
                dec = p2.children()[0];
              }
              else if ((p2.children()[1].abspid() == 411 || p2.children()[1].abspid() == 421)
                       && (p2.children()[0].abspid() == 111 || p2.children()[0].abspid() == 211)) {
                dec = p2.children()[1];
              }
              else
                continue;
              const LorentzTransform boost2 = LorentzTransform::mkFrameTransformFromBeta(pD.betaVec());
              FourMomentum pDec = boost2.transform(boost.transform(dec.momentum()));
              // decay angle
              double cTheta = pDec.p3().unit().dot(pD.p3().unit());
              if (p2.abspid() == 423) {
                _b[1]->fill(x, cTheta);
                _p[1]->fill(x, -1. / 2. * (1. - 5. * sqr(cTheta)));
              }
              else {
                _b[0]->fill(x, cTheta);
                _p[0]->fill(x, -1. / 2. * (1. - 5. * sqr(cTheta)));
              }
            }
          }
        }
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      // spectra
      normalize(_h, 1.0, false);
      for (unsigned int ix = 0; ix < 2; ++ix) {
        // angles dists
        normalize(_b[ix], 1.0, false);
        // polarizations
        Estimate1DPtr tmp;
        book(tmp, 7, 1, 1 + ix);
        for (const auto& b : _p[ix]->bins()) {
          const double val = b.numEntries() > 0 && b.effNumEntries() > 0 ? b.yMean() : 0.;
          const double err = b.numEntries() > 1 && b.effNumEntries() > 1 ? b.yStdErr() : 0.;
          const double l1 = 2. * val / (1. + val);
          const double e1 = 2. / sqr(1. + val) * err;
          tmp->bin(b.index()).set(l1, e1);
        }
      }
    }

    /// @}


    /// @name Histograms
    /// @{
    Histo1DPtr _h[4];
    Profile1DPtr _p[2];
    Histo1DGroupPtr _b[2];
    /// @}
  };


  RIVET_DECLARE_PLUGIN(CLEOII_1997_I440969);

}