Rivet analyses

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

namespace Rivet {


  /// @brief B- -> D*0 K*-
  class BABAR_2004_I626518 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(BABAR_2004_I626518);


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

    /// Book histograms and initialise projections before the run
    void init() {
      // Initialise and register projections
      UnstableParticles ufs = UnstableParticles(Cuts::abspid == 521);
      declare(ufs, "UFS");
      DecayedParticles BP(ufs);
      BP.addStable(423);
      BP.addStable(-423);
      BP.addStable(323);
      BP.addStable(-323);
      declare(BP, "BP");
      // histos
      for (unsigned int ix = 0; ix < 2; ++ix)
        for (unsigned int iy = 0; iy < 2; ++iy) book(_h[ix][iy], 2, 1 + ix, 1 + iy);
      for (unsigned int ix = 0; ix < 2; ++ix) book(_p[ix], "TMP/p_" + toString(ix + 1));
    }

    bool isK(int id) {
      return id == 321 || id == 311 || id == 310 || id == 130;
    }

    bool isPi(int id) {
      return id == 211 || id == 111;
    }

    /// Perform the per-event analysis
    void analyze(const Event& event) {
      static const map<PdgId, unsigned int>& mode = {{-423, 1}, {323, 1}};
      static const map<PdgId, unsigned int>& modeCC = {{423, 1}, {-323, 1}};
      DecayedParticles BP = apply<DecayedParticles>(event, "BP");
      // loop over particles
      for (unsigned int ix = 0; ix < BP.decaying().size(); ++ix) {
        int sign = 1;
        if (BP.decaying()[ix].pid() > 0 && BP.modeMatches(ix, 2, mode))
          sign = 1.;
        else if (BP.decaying()[ix].pid() < 0 && BP.modeMatches(ix, 2, modeCC))
          sign = -1.;
        else
          continue;
        // find D* decay products
        const Particle& Dstar = BP.decayProducts()[ix].at(-sign * 423)[0];
        if (Dstar.children().size() != 2) continue;
        Particle D0;
        unsigned int imode = 0;
        if (Dstar.children()[0].pid() == 111 && Dstar.children()[1].pid() == -sign * 421) {
          D0 = Dstar.children()[1];
          imode = 0;
        }
        else if (Dstar.children()[1].pid() == 111 && Dstar.children()[0].pid() == -sign * 421) {
          imode = 0;
          D0 = Dstar.children()[0];
        }
        else if (Dstar.children()[0].pid() == 22 && Dstar.children()[1].pid() == -sign * 421) {
          D0 = Dstar.children()[1];
          imode = 1;
        }
        else if (Dstar.children()[1].pid() == 22 && Dstar.children()[0].pid() == -sign * 421) {
          imode = 1;
          D0 = Dstar.children()[0];
        }
        else
          continue;
        // K* decay products
        const Particle& Kstar = BP.decayProducts()[ix].at(sign * 323)[0];
        if (Kstar.children().size() != 2) continue;
        Particle KK;
        if (isK(Kstar.children()[0].abspid()) && isPi(Kstar.children()[1].abspid()))
          KK = Kstar.children()[0];
        else if (isK(Kstar.children()[1].abspid()) && isPi(Kstar.children()[0].abspid()))
          KK = Kstar.children()[1];
        else
          continue;
        // boost to B rest frame
        LorentzTransform boost = LorentzTransform::mkFrameTransformFromBeta(
            BP.decaying()[ix].momentum().betaVec());
        FourMomentum pKstar = boost.transform(Kstar.momentum());
        FourMomentum pDstar = boost.transform(Dstar.momentum());
        FourMomentum pK = boost.transform(KK.momentum());
        FourMomentum pD = boost.transform(D0.momentum());
        const LorentzTransform boost2 = LorentzTransform::mkFrameTransformFromBeta(pDstar.betaVec());
        pD = boost2.transform(pD);
        double cD = pD.p3().unit().dot(pDstar.p3().unit());
        const LorentzTransform boost3 = LorentzTransform::mkFrameTransformFromBeta(pKstar.betaVec());
        pK = boost3.transform(pK);
        double cK = pK.p3().unit().dot(pKstar.p3().unit());
        if (imode == 0) {
          _p[0]->fill(-0.5 * (1 - 5 * sqr(cK)));
          _p[1]->fill();
        }
        _h[0][imode]->fill(cD);
        _h[1][imode]->fill(cK);
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      for (unsigned int ix = 0; ix < 2; ++ix)
        for (unsigned int iy = 0; iy < 2; ++iy) normalize(_h[ix][iy], 1., false);
      Estimate0DPtr tmp;
      book(tmp, 1, 1, 1);
      divide(*_p[0], *_p[1], tmp);
    }

    /// @}


    /// @name Histograms
    /// @{
    Histo1DPtr _h[2][2];
    CounterPtr _p[2];
    /// @}
  };


  RIVET_DECLARE_PLUGIN(BABAR_2004_I626518);

}