Rivet analyses

title: CLEO_1985_I218314

Momentum spectrum of $\phi$ mesons in $B$ decays

Experiment: CLEO (CESR)

Inspire ID: 218314

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Phys.Rev.Lett. 56 (1986) 800

Beams: * *

Beam energies: ANY

Run details: - Any process producing Upslion(4S), originaly e+e-

Momentum spectrum of $\phi$ mesons in $B$ meson decays, where the $B$ mesons are produced at the $\Upsilon(4S)$

Source code:CLEO_1985_I218314.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief B -> phi X class CLEO_1985_I218314 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(CLEO_1985_I218314);


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

/// Book histograms and initialise projections before the run
void init() {
  // projections
  declare(UnstableParticles(Cuts::pid == 300553), "UFS");
  // histograms
  book(_h, 4, 1, 1);
  book(_c, "TMP/nB");
}

void findDecay(const Particle& parent, Particles& phi) {
  for (const Particle& p : parent.children()) {
    if (p.abspid() == 333) {
      phi.push_back(p);
    }
    else if (p.abspid() == PID::PIPLUS || p.abspid() == PID::KPLUS || p.pid() == PID::PI0
             || p.pid() == PID::K0S)
      continue;
    else if (!p.children().empty()) {
      findDecay(p, phi);
    }
  }
}


/// Perform the per-event analysis
void analyze(const Event& event) {
  const UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");
  for (const Particle& p : ufs.particles()) {
    const LorentzTransform boost = LorentzTransform::mkFrameTransformFromBeta(p.mom().betaVec());
    for (const Particle& B : p.children()) {
      if (B.abspid() != 511 && B.abspid() != 521) continue;
      _c->fill();
      Particles phi;
      findDecay(B, phi);
      for (const Particle& p2 : phi) {
        const double pmod = boost.transform(p2.mom()).p3().mod();
        _h->fill(pmod);
      }
    }
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  scale(_h, 1. / *_c);
}

/// @}


/// @name Histograms
/// @{
Histo1DPtr _h;
CounterPtr _c;
/// @}

};

RIVET_DECLARE_PLUGIN(CLEO_1985_I218314);

} ```