Rivet analyses

title: BELLE_2005_I665011

Electron spectrum in semileptonic $B$ meson decays

Experiment: BELLE (KEKB)

Inspire ID: 665011

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: none listed

Beams: * *

Beam energies: ANY

Run details: - Any process producing B0 and B+ mesons, originally Upsilon(4S) decays

Measurement of the electron spectrum in semileptonic $B$ meson decays, the data are fully corrected and were taken from Table 2 in the paper.

Source code:BELLE_2005_I665011.cc

```c++ // -- C++ --

include "Rivet/Analysis.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief e- spectrum in semileptonic B decays class BELLE_2005_I665011 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BELLE_2005_I665011);


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

/// Book histograms and initialise projections before the run
void init() {
  // projection
  declare(UnstableParticles(Cuts::abspid == 511 || Cuts::abspid == 521), "UFS");
  // histos
  for (unsigned int ix = 0; ix < 2; ++ix) {
    book(_h[ix], 1, 1, 1 + ix);
    book(_c[ix], "TMP/c_" + toString(ix + 1));
  }
}

void findDecayProducts(const Particle& parent,
                       Particles& em,
                       Particles& ep,
                       Particles& nue,
                       Particles& nueBar,
                       bool& charm) {
  for (const Particle& p : parent.children()) {
    if (PID::isCharmHadron(p.pid())) {
      charm = true;
    }
    else 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::isBottomHadron(p.pid())) {
      findDecayProducts(p, em, ep, nue, nueBar, charm);
    }
    else if (!PID::isHadron(p.pid())) {
      findDecayProducts(p, em, ep, nue, nueBar, charm);
    }
  }
}

/// Perform the per-event analysis
void analyze(const Event& event) {
  // find and loop over B mesos
  for (const Particle& p : apply<UnstableParticles>(event, "UFS").particles()) {
    unsigned int iB = (p.abspid() - 511) / 10;
    _c[iB]->fill();
    // find decay products
    bool charm = false;
    Particles em, ep, nue, nueBar;
    findDecayProducts(p, em, ep, nue, nueBar, charm);
    if (!charm) continue;
    LorentzTransform boost = LorentzTransform::mkFrameTransformFromBeta(p.momentum().betaVec());
    double pmod(0.);
    if (em.size() == 1 && nueBar.size() == 1) {
      pmod = boost.transform(em[0].momentum()).p3().mod();
    }
    else if (ep.size() == 1 && nue.size() == 1) {
      pmod = boost.transform(ep[0].momentum()).p3().mod();
    }
    else {
      continue;
    }
    _h[iB]->fill(pmod);
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  // normalize hists
  for (unsigned int ix = 0; ix < 2; ++ix) {
    scale(_h[ix], 1. / *_c[ix]);
  }
  // ratio
  Estimate1DPtr ratio;
  book(ratio, 1, 1, 3);
  divide(_h[1], _h[0], ratio);
}

/// @}


/// @name Histograms
/// @{
Histo1DPtr _h[2];
CounterPtr _c[2];
/// @}

};

RIVET_DECLARE_PLUGIN(BELLE_2005_I665011);

} ```