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);

}