Rivet analyses

Electron spectrum inclusive semi-leptonic in D decays

Experiment: CLEOC (CESR)

Inspire ID: 715096

Status: VALIDATED

Authors: - Peter Richardson

References: - Phys.Rev.Lett. 97 (2006) 251801

Beams: * *

Beam energies: ANY

Run details: - charm mesons produced at the psi(3770)

Measurement of the electron spectrum inclusive semi-leptonic in D decays. N.B. The spectum is obtained in the rest frame of the decaying ψ(3770) which produces the decaying D mesons

Source code:CLEOC_2006_I715096.cc

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

namespace Rivet {


  /// @brief Electron spectrum in D decays
  class CLEOC_2006_I715096 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(CLEOC_2006_I715096);


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

    /// Book histograms and initialise projections before the run
    void init() {
      // projections
      declare(UnstableParticles(),"UFS");
      // Book histograms
      // specify custom binning
      book(_h_Dp, 1,1,1);
      book(_h_D0, 1,1,2);
    }

    void findDecayProducts(Particle parent, Particles & em, Particles & ep,
               Particles & nue, Particles & nueBar) {
      for(const Particle & p : parent.children()) {
    if(p.pid() == PID::EMINUS) {
      em.push_back(p);
    }
    else if(p.pid() == PID::EPLUS) {
      ep.push_back(p);
    }
    else if(p.pid() == PID::NU_E) {
      nue.push_back(p);
    }
    else if(p.pid() == PID::NU_EBAR) {
      nueBar.push_back(p);
    }
    else if(PID::isCharmHadron(p.pid())) {
      findDecayProducts(p,em,ep,nue,nueBar);
    }
    else if(!PID::isHadron(p.pid())) {
      findDecayProducts(p,em,ep,nue,nueBar);
    }
      }
    }

    /// Perform the per-event analysis
    void analyze(const Event& event) {
      // find and loop over psi(3770)
      const UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");
      for (const Particle& p : ufs.particles(Cuts::pid==30443)) {
    // boost to rest frame
    LorentzTransform boost;
    if (p.p3().mod() > 1*MeV)
      boost = LorentzTransform::mkFrameTransformFromBeta(p.momentum().betaVec());
    // loop over decay products
    for(const Particle & p2 : p.children()) {
      if(p2.abspid()==411 || p2.abspid()==421) {
        Particles em,ep,nue,nueBar;
        findDecayProducts(p2,em,ep,nue,nueBar);
        if(em.size()==1 && nueBar.size()==1) {
          double pmod = boost.transform(em[0].momentum()).p3().mod();
          if(p2.abspid()==411) _h_Dp->fill(pmod);
          else                 _h_D0->fill(pmod);
        }
        else if(ep.size()==1 && nue.size()==1) {
          double pmod = boost.transform(ep[0].momentum()).p3().mod();
          if(p2.abspid()==411) _h_Dp->fill(pmod);
          else                 _h_D0->fill(pmod);
        }
      }
    }
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      normalize(_h_D0);
      normalize(_h_Dp);
    }

    /// @}


    /// @name Histograms
    /// @{
    Histo1DPtr _h_Dp,_h_D0;
    /// @}


  };


  RIVET_DECLARE_PLUGIN(CLEOC_2006_I715096);

}