Rivet analyses

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

namespace Rivet {


  /// @brief p, Lambda, Lambda_c and Xi spectra at Upsilon(4s)
  class CLEO_1992_I315181 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(CLEO_1992_I315181);


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

    /// Book histograms and initialise projections before the run
    void init() {
      declare(UnstableParticles(), "UFS");
      book(_c_ups, "/TMP/c_ups");
      book(_h_p, 1, 1, 1);
      book(_h_Lambda_c, 2, 1, 1);
      book(_h_Lambda, 3, 1, 1);
      book(_h_Xi, 4, 1, 1);
    }

    void findDecayProducts(Particle parent,
                           Particles& protons,
                           Particles& lambda_c,
                           Particles& lambda,
                           Particles& xi) {
      for (const Particle& p : parent.children()) {
        if (p.abspid() == PID::PROTON) {
          protons.push_back(p);
          continue;
        }
        else if (p.abspid() == PID::LAMBDA) {
          lambda.push_back(p);
          continue;
        }
        else if (p.abspid() == PID::XIMINUS) {
          xi.push_back(p);
        }
        else if (p.abspid() == 4122) {
          lambda_c.push_back(p);
        }
        if (!p.children().empty()) findDecayProducts(p, protons, lambda_c, lambda, xi);
      }
    }

    /// Perform the per-event analysis
    void analyze(const Event& event) {
      // Find the upsilons
      for (const Particle& ups : apply<UnstableParticles>(event, "UFS").particles(Cuts::pid == 300553)) {
        _c_ups->fill();
        Particles protons, lambda_c, lambda, xi;
        findDecayProducts(ups, protons, lambda_c, lambda, xi);
        LorentzTransform boost;
        if (ups.p3().mod() > 1 * MeV)
          boost = LorentzTransform::mkFrameTransformFromBeta(ups.momentum().betaVec());
        for (const Particle& p : protons) {
          double pcm = boost.transform(p.momentum()).p3().mod();
          _h_p->fill(pcm);
        }
        for (const Particle& p : lambda_c) {
          double pcm = boost.transform(p.momentum()).p3().mod();
          _h_Lambda_c->fill(pcm);
        }
        for (const Particle& p : lambda) {
          double pcm = boost.transform(p.momentum()).p3().mod();
          _h_Lambda->fill(pcm);
        }
        for (const Particle& p : xi) {
          double pcm = boost.transform(p.momentum()).p3().mod();
          _h_Xi->fill(pcm);
        }
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      // br for lambda_c mode used (p K- pi+)
      double br = 0.0623;
      scale(_h_p, 0.5 / *_c_ups);
      scale(_h_Lambda_c, 0.5 * br / *_c_ups);
      scale(_h_Lambda, 0.5 / *_c_ups);
      scale(_h_Xi, 0.5 / *_c_ups);
    }

    /// @}


    /// @name Histograms
    /// @{
    CounterPtr _c_ups;
    Histo1DPtr _h_p, _h_Lambda_c, _h_Lambda, _h_Xi;
    /// @}
  };


  RIVET_DECLARE_PLUGIN(CLEO_1992_I315181);

}