Rivet analyses

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

namespace Rivet {


  /// @brief D -> pi,K semi-leptonic q^2
  class CLEOC_2008_I769777 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(CLEOC_2008_I769777);


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

    /// Book histograms and initialise projections before the run
    void init() {

      // Initialise and register projections
      declare(UnstableParticles(), "UFS");
      // histograms
      book(_h_q2_D0_pi, 1, 1, 1);
      book(_h_q2_Dp_pi, 1, 1, 2);
      book(_h_q2_D0_K, 1, 1, 3);
      book(_h_q2_Dp_K, 1, 1, 4);
      book(_nD0, "TMP/nD0");
      book(_nDp, "TMP/nDp");
    }

    // Calculate the Q2 using mother and daugher meson
    double q2(const Particle& B, int mesonID) {
      FourMomentum q = B.mom() - select(B.children(), Cuts::abspid == abs(mesonID))[0];
      return q * q;
    }

    // Check for explicit decay into pdgids
    bool isSemileptonicDecay(const Particle& mother, vector<int> ids) {
      // Trivial check to ignore any other decays but the one in question modulo photons
      const Particles children = mother.children(Cuts::pid != PID::PHOTON);
      if (children.size() != ids.size()) return false;
      // Check for the explicit decay
      return all(ids, [&](int i) { return count(children, hasPID(i)) == 1; });
    }

    /// Perform the per-event analysis
    void analyze(const Event& event) {
      // Loop over D mesons
      for (const Particle& p : apply<UnstableParticles>(event, "UFS")
                                   .particles(Cuts::abspid == PID::D0 or Cuts::abspid == PID::DPLUS)) {
        if (p.abspid() == PID::D0) {
          _nD0->fill();
          if (isSemileptonicDecay(p, {PID::PIMINUS, PID::POSITRON, PID::NU_E})
              || isSemileptonicDecay(p, {PID::PIPLUS, PID::ELECTRON, PID::NU_EBAR}))
            _h_q2_D0_pi->fill(q2(p, PID::PIMINUS));
          else if (isSemileptonicDecay(p, {PID::KMINUS, PID::POSITRON, PID::NU_E})
                   || isSemileptonicDecay(p, {PID::KPLUS, PID::ELECTRON, PID::NU_EBAR}))
            _h_q2_D0_K->fill(q2(p, PID::KMINUS));
        }
        else if (p.abspid() == PID::DPLUS) {
          _nDp->fill();
          if (isSemileptonicDecay(p, {PID::PI0, PID::POSITRON, PID::NU_E})
              || isSemileptonicDecay(p, {PID::PI0, PID::ELECTRON, PID::NU_EBAR}))
            _h_q2_Dp_pi->fill(q2(p, PID::PI0));
          else if (isSemileptonicDecay(p, {-311, PID::POSITRON, PID::NU_E}))
            _h_q2_Dp_K->fill(q2(p, -311));
          else if (isSemileptonicDecay(p, {311, PID::ELECTRON, PID::NU_EBAR}))
            _h_q2_Dp_K->fill(q2(p, 311));
          else if (isSemileptonicDecay(p, {PID::K0S, PID::POSITRON, PID::NU_E})
                   || isSemileptonicDecay(p, {PID::K0S, PID::ELECTRON, PID::NU_EBAR}))
            _h_q2_Dp_K->fill(q2(p, PID::K0S));
          else if (isSemileptonicDecay(p, {PID::K0L, PID::POSITRON, PID::NU_E})
                   || isSemileptonicDecay(p, {PID::K0L, PID::ELECTRON, PID::NU_EBAR}))
            _h_q2_Dp_K->fill(q2(p, PID::K0L));
        }
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      scale(_h_q2_D0_pi, 100. / *_nD0);
      scale(_h_q2_D0_K, 100. / *_nD0);
      scale(_h_q2_Dp_pi, 100. / *_nDp);
      scale(_h_q2_Dp_K, 100. / *_nDp);
    }

    /// @}


    /// @name Histograms
    /// @{
    Histo1DPtr _h_q2_D0_pi, _h_q2_D0_K, _h_q2_Dp_pi, _h_q2_Dp_K;
    CounterPtr _nD0, _nDp;
    /// @}
  };


  RIVET_DECLARE_PLUGIN(CLEOC_2008_I769777);

}