Rivet analyses

title: CLEOC_2006_I715096

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 $\psi(3770)$ which produces the decaying $D$ mesons

Source code:CLEOC_2006_I715096.cc

```c++ // -- 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);

} ```