Rivet analyses

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

namespace Rivet {


  /// @brief B -> D* rho
  class CLEOII_2003_I611745 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(CLEOII_2003_I611745);


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

    /// Book histograms and initialise projections before the run
    void init() {
      // Initialise and register projections
      UnstableParticles ufs = UnstableParticles(Cuts::abspid == 511 || Cuts::abspid == 521);
      declare(ufs, "UFS");
      DecayedParticles BB(ufs);
      BB.addStable(423);
      BB.addStable(-423);
      BB.addStable(413);
      BB.addStable(-413);
      BB.addStable(213);
      BB.addStable(-213);
      BB.addStable(113);
      declare(BB, "BB");
      // histos
      for (unsigned int ix = 0; ix < 2; ++ix) {
        for (unsigned int iy = 0; iy < 3; ++iy) {
          book(_h[ix][iy], 2, 1 + iy, 1 + ix);
          if (iy < 2) book(_p[ix][iy], "TMP/TMP_" + toString(ix) + "_" + toString(iy));
        }
      }
    }


    /// Perform the per-event analysis
    void analyze(const Event& event) {
      DecayedParticles BB = apply<DecayedParticles>(event, "BB");
      // loop over particles
      for (unsigned int ix = 0; ix < BB.decaying().size(); ++ix) {
        int sign = BB.decaying()[ix].pid() / BB.decaying()[ix].abspid();
        unsigned int imode = 0;
        if ((BB.decaying()[ix].pid() == 521 && BB.modeMatches(ix, 2, mode1))
            || (BB.decaying()[ix].pid() == -521 && BB.modeMatches(ix, 2, mode1CC)))
          imode = 0;
        else if ((BB.decaying()[ix].pid() == 511 && BB.modeMatches(ix, 2, mode2))
                 || (BB.decaying()[ix].pid() == -511 && BB.modeMatches(ix, 2, mode2CC)))
          imode = 1;
        else
          continue;
        // find D* decay products
        const Particle& Dstar = BB.decayProducts()[ix].at(-sign * (423 - 10 * imode))[0];
        if (Dstar.children().size() != 2) continue;
        Particle D0;
        int ipi = imode == 0 ? 111 : -sign * 211;
        if (Dstar.children()[0].pid() == ipi && Dstar.children()[1].abspid() == -sign * 421) {
          D0 = Dstar.children()[1];
        }
        else if (Dstar.children()[1].pid() == ipi && Dstar.children()[0].abspid() == -sign * 421) {
          D0 = Dstar.children()[0];
        }
        else {
          continue;
        }
        // rho decay products
        const Particle& rho = BB.decayProducts()[ix].at(sign * 213)[0];
        if (rho.children().size() != 2) continue;
        Particle pip;
        if (rho.children()[1].pid() == 111 && rho.children()[0].pid() == sign * 211)
          pip = rho.children()[0];
        else if (rho.children()[0].pid() == 111 && rho.children()[1].pid() == sign * 211)
          pip = rho.children()[1];
        else {
          continue;
        }
        // boost to B rest frame
        LorentzTransform boost = LorentzTransform::mkFrameTransformFromBeta(
            BB.decaying()[ix].mom().betaVec());
        FourMomentum prho = boost.transform(rho.mom());
        FourMomentum pDstar = boost.transform(Dstar.mom());
        FourMomentum pPi = boost.transform(pip.mom());
        FourMomentum pD = boost.transform(D0.mom());
        const LorentzTransform boost2 = LorentzTransform::mkFrameTransformFromBeta(pDstar.betaVec());
        pD = boost2.transform(pD);
        double cD = pD.p3().unit().dot(pDstar.p3().unit());
        Vector3 trans1 = pD.p3().unit() - cD * pDstar.p3().unit();
        _h[imode][0]->fill(cD);
        const LorentzTransform boost3 = LorentzTransform::mkFrameTransformFromBeta(prho.betaVec());
        pPi = boost3.transform(pPi);
        double cPi = pPi.p3().unit().dot(prho.p3().unit());
        Vector3 trans2 = pPi.p3().unit() - cPi * prho.p3().unit();
        _h[imode][1]->fill(cPi);
        double chi = atan2(trans1.cross(trans2).dot(prho.p3().unit()), trans1.dot(trans2));
        _h[imode][2]->fill(chi);
        _p[imode][0]->fill(-0.5 * (1 - 5 * sqr(cPi)));
        _p[imode][1]->fill();
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      for (unsigned int ix = 0; ix < 2; ++ix) {
        normalize(_h[ix], 1.0, false);
        Estimate0DPtr tmp;
        book(tmp, 1, 1, 1 + ix);
        divide(*_p[ix][0], *_p[ix][1], tmp);
      }
    }

    /// @}


    /// @name Histograms
    /// @{
    Histo1DPtr _h[2][3];
    CounterPtr _p[2][2];
    const map<PdgId, unsigned int> mode1 = {{-423, 1}, {213, 1}};
    const map<PdgId, unsigned int> mode1CC = {{423, 1}, {-213, 1}};
    const map<PdgId, unsigned int> mode2 = {{-413, 1}, {213, 1}};
    const map<PdgId, unsigned int> mode2CC = {{413, 1}, {-213, 1}};
    /// @}
  };


  RIVET_DECLARE_PLUGIN(CLEOII_2003_I611745);

}