Rivet analyses

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

namespace Rivet {


  /// @brief D_1+ and D_2 spectra
  class CLEOII_1994_I378319 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(CLEOII_1994_I378319);


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

    /// Book histograms and initialise projections before the run
    void init() {
      // projections
      declare(Beam(), "Beams");
      declare(UnstableParticles(), "UFS");
      // book histos
      book(_h_D2_cTheta,2,1,1);
      book(_h_D2_x     ,4,1,1);
      book(_h_D1_cTheta,3,1,1);
      book(_h_D1_x     ,4,1,2);
      for(unsigned int ix=0;ix<3;++ix)
    book(_r[ix],5,1,ix+1);
    }


    /// Perform the per-event analysis
    void analyze(const Event& event) {
      static const int idD1 = 10413;
      static const int idD2 = 415;
      // Get beams and average beam momentum
      const ParticlePair& beams = apply<Beam>(event, "Beams").beams();
      const double Emax = ( beams.first.p3().mod() + beams.second.p3().mod() ) / 2.0;
      const UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");
      for (const Particle& p : ufs.particles(Cuts::abspid==idD1 or Cuts::abspid==idD2)) {
    if(p.abspid()==idD1) {
      // spectrum
      double Pmax = sqrt(sqr(Emax)-sqr(2.421));
      double xp = p.momentum().p3().mod()/Pmax;
      _h_D1_x->fill(xp);
    }
    else {
      double Pmax = sqrt(sqr(Emax)-sqr(2.461));
      double xp = p.momentum().p3().mod()/Pmax;
      _h_D2_x->fill(xp);
    }
    int sign = p.pid()/p.abspid();
    Particle Dstar;
    if(p.children().size()!=2) continue;
    if(p.children()[0].pid()==sign*423 &&
       p.children()[1].pid()==sign*211) {
      Dstar = p.children()[0];
    }
    else if(p.children()[1].pid()==sign*423 &&
        p.children()[0].pid()==sign*211) {
      Dstar = p.children()[1];
    }
    else if(p.children()[0].pid()==sign*421 &&
       p.children()[1].pid()==sign*211) {
      if(p.abspid()!=idD1) _r[0]->fill("10.58"s);
      continue;
    }
    else if(p.children()[1].pid()==sign*421 &&
        p.children()[0].pid()==sign*211) {
      if(p.abspid()!=idD1) _r[0]->fill("10.58"s);
      continue;
    }
    else {
      continue;
    }
    if(p.abspid()==idD1)
      _r[2]->fill("10.58"s);
    else
      _r[1]->fill("10.58"s);
    if(Dstar.children().size()!=2) continue;
    Particle pion;
    if(Dstar.children()[0].pid()== 111 &&
       Dstar.children()[1].pid()== sign*421) {
      pion = Dstar.children()[0];
    }
    else if(Dstar.children()[1].pid()== 111 &&
        Dstar.children()[0].pid()== sign*421) {
      pion = Dstar.children()[1];
    }
    else
      continue;
    // first boost to the D_1,2 rest frame
    LorentzTransform boost1 = LorentzTransform::mkFrameTransformFromBeta(p.momentum().betaVec());
    FourMomentum pDstar = boost1.transform(Dstar.momentum());
    FourMomentum pPion  = boost1.transform(pion .momentum());
    // to D* rest frame
    LorentzTransform boost2 = LorentzTransform::mkFrameTransformFromBeta(pDstar.betaVec());
    Vector3 axis = pDstar.p3().unit();
    FourMomentum pp = boost2.transform(pPion);
    // calculate angle
    double cTheta = pp.p3().unit().dot(axis);
    if(p.abspid()==idD1)
      _h_D1_cTheta->fill(cTheta);
    else
      _h_D2_cTheta->fill(cTheta);
      }
    }

    /// Normalise histograms etc., after the run
    void finalize() {
      normalize(_h_D2_cTheta);
      normalize(_h_D2_x     );
      normalize(_h_D1_cTheta);
      normalize(_h_D1_x     );
      for(unsigned int ix=0;ix<3;++ix)
    scale(_r[ix],crossSection()/sumOfWeights()/picobarn);
    }

    /// @}


    /// @name Histograms
    /// @{
    Histo1DPtr _h_D2_cTheta,_h_D2_x,_h_D1_cTheta,_h_D1_x;
    BinnedHistoPtr<string> _r[3];
    /// @}


  };


  RIVET_DECLARE_PLUGIN(CLEOII_1994_I378319);

}