Rivet analyses

title: CLEO_1992_I315181

Baryon spectra in $\Upsilon(4S)$ decays

Experiment: CLEO (CESR)

Inspire ID: 315181

Status: VALIDATED

Authors: - Peter Richardson

References: - Phys.Rev. D45 (1992) 752-770

Beams: * *

Beam energies: ANY

Run details: - Any processs producing Upslion(4S), originally e+e-

Measurement of the proton, $\Lambda_c^+$, $\Lambda$ and $\Xi^-$ momentum spectra in B decays at the $\Upsilon(4S)$ by CLEO.

Source code:CLEO_1992_I315181.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief p, Lambda, Lambda_c and Xi spectra at Upsilon(4s) class CLEO_1992_I315181 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(CLEO_1992_I315181);


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

/// Book histograms and initialise projections before the run
void init() {
  declare(UnstableParticles(), "UFS");
  book(_c_ups, "/TMP/c_ups");
  book(_h_p, 1, 1, 1);
  book(_h_Lambda_c, 2, 1, 1);
  book(_h_Lambda, 3, 1, 1);
  book(_h_Xi, 4, 1, 1);
}

void findDecayProducts(Particle parent,
                       Particles& protons,
                       Particles& lambda_c,
                       Particles& lambda,
                       Particles& xi) {
  for (const Particle& p : parent.children()) {
    if (p.abspid() == PID::PROTON) {
      protons.push_back(p);
      continue;
    }
    else if (p.abspid() == PID::LAMBDA) {
      lambda.push_back(p);
      continue;
    }
    else if (p.abspid() == PID::XIMINUS) {
      xi.push_back(p);
    }
    else if (p.abspid() == 4122) {
      lambda_c.push_back(p);
    }
    if (!p.children().empty()) findDecayProducts(p, protons, lambda_c, lambda, xi);
  }
}

/// Perform the per-event analysis
void analyze(const Event& event) {
  // Find the upsilons
  for (const Particle& ups : apply<UnstableParticles>(event, "UFS").particles(Cuts::pid == 300553)) {
    _c_ups->fill();
    Particles protons, lambda_c, lambda, xi;
    findDecayProducts(ups, protons, lambda_c, lambda, xi);
    LorentzTransform boost;
    if (ups.p3().mod() > 1 * MeV)
      boost = LorentzTransform::mkFrameTransformFromBeta(ups.momentum().betaVec());
    for (const Particle& p : protons) {
      double pcm = boost.transform(p.momentum()).p3().mod();
      _h_p->fill(pcm);
    }
    for (const Particle& p : lambda_c) {
      double pcm = boost.transform(p.momentum()).p3().mod();
      _h_Lambda_c->fill(pcm);
    }
    for (const Particle& p : lambda) {
      double pcm = boost.transform(p.momentum()).p3().mod();
      _h_Lambda->fill(pcm);
    }
    for (const Particle& p : xi) {
      double pcm = boost.transform(p.momentum()).p3().mod();
      _h_Xi->fill(pcm);
    }
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  // br for lambda_c mode used (p K- pi+)
  double br = 0.0623;
  scale(_h_p, 0.5 / *_c_ups);
  scale(_h_Lambda_c, 0.5 * br / *_c_ups);
  scale(_h_Lambda, 0.5 / *_c_ups);
  scale(_h_Xi, 0.5 / *_c_ups);
}

/// @}


/// @name Histograms
/// @{
CounterPtr _c_ups;
Histo1DPtr _h_p, _h_Lambda_c, _h_Lambda, _h_Xi;
/// @}

};

RIVET_DECLARE_PLUGIN(CLEO_1992_I315181);

} ```