Rivet analyses

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

namespace Rivet {


  /// @brief  D0 -> K- pi+ pi0
  class CLEOII_2001_I537154 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(CLEOII_2001_I537154);


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

    /// Book histograms and initialise projections before the run
    void init() {
      // Initialise and register projections
      UnstableParticles ufs = UnstableParticles(Cuts::abspid == 421);
      declare(ufs, "UFS");
      DecayedParticles D0(ufs);
      D0.addStable(PID::PI0);
      D0.addStable(PID::K0S);
      D0.addStable(PID::ETA);
      D0.addStable(PID::ETAPRIME);
      declare(D0, "D0");
      // histograms
      book(_h_Kpi0, 1, 1, 1);
      book(_h_Kpip, 1, 2, 1);
      book(_h_pipi, 1, 3, 1);
    }

    /// Perform the per-event analysis
    void analyze(const Event& event) {
      static const double E0 = 22.1e-5;
      static const double Ex = -6.89e-5;
      static const double Ey = -27.1e-5;
      static const double Ex2 = 10.4e-5;
      static const double Exy = 38.2e-5;
      static const double Ey2 = 12.4e-5;
      static const double Ex3 = -3.00e-5;
      static const double Ex2y = -7.97e-5;
      static const double Exy2 = -12.8e-5;
      static const double Ey3 = -0.53e-5;

      static const map<PdgId, unsigned int>& mode = {{-321, 1}, {211, 1}, {111, 1}};
      static const map<PdgId, unsigned int>& modeCC = {{321, 1}, {-211, 1}, {111, 1}};
      DecayedParticles D0 = apply<DecayedParticles>(event, "D0");
      // loop over particles
      for (unsigned int ix = 0; ix < D0.decaying().size(); ++ix) {
        int sign = 1;
        if (D0.decaying()[ix].pid() > 0 && D0.modeMatches(ix, 3, mode)) {
          sign = 1;
        }
        else if (D0.decaying()[ix].pid() < 0 && D0.modeMatches(ix, 3, modeCC)) {
          sign = -1;
        }
        else
          continue;
        const Particles& pi0 = D0.decayProducts()[ix].at(111);
        const Particles& Km = D0.decayProducts()[ix].at(-sign * 321);
        const Particles& pip = D0.decayProducts()[ix].at(sign * 211);
        double mKpip = (Km[0].momentum() + pip[0].momentum()).mass2();
        double mKpi0 = (Km[0].momentum() + pi0[0].momentum()).mass2();
        double mpipi = (pi0[0].momentum() + pip[0].momentum()).mass2();
        double eff = E0 + Ex * mKpip + Ey * mpipi + Ex2 * sqr(mKpip) + Exy * mKpip * mpipi + Ey2 * sqr(mpipi)
            + Ex3 * pow(mKpip, 3) + Ex2y * sqr(mKpip) * mpipi + Exy2 * mKpip * sqr(mpipi)
            + Ey3 * pow(mpipi, 3);
        _h_Kpi0->fill(mKpi0, eff);
        _h_Kpip->fill(mKpip, eff);
        _h_pipi->fill(mpipi, eff);
      }
    }

    /// Normalise histograms etc., after the run
    void finalize() {
      normalize(_h_Kpi0);
      normalize(_h_Kpip);
      normalize(_h_pipi);
    }

    /// @}


    /// @name Histograms
    /// @{
    Histo1DPtr _h_Kpi0, _h_Kpip, _h_pipi;
    /// @}
  };


  RIVET_DECLARE_PLUGIN(CLEOII_2001_I537154);

}