Rivet analyses

title: ARGUS_1992_I334962

Proton and $\Lambda$ momentum spectrum in B decays

Experiment: ARGUS (DORIS)

Inspire ID: 334962

Status: VALIDATED NOHEPDATA

Authors: - Peter Richardson

References: - Z.Phys.C 56 (1992) 1-6

Beams: * *

Beam energies: ANY

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

Measurement of the proton and $\Lambda$ momentum spectrum in B decays by ARGUS. The corrected data were read from the figures in the paper.

Source code:ARGUS_1992_I334962.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief B-> baryons class ARGUS_1992_I334962 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(ARGUS_1992_I334962);


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

/// Book histograms and initialise projections before the run
void init() {
  // projections
  declare(UnstableParticles(), "UFS");
  // histos
  for (unsigned int ix = 0; ix < 2; ++ix) {
    book(_h_spect[ix], 1 + ix, 1, 1);
    book(_h_flav[ix], 3, 1, 1 + ix);
  }
}

void findDecayProducts(const Particle& parent,
                       Particles& protons_all,
                       Particles& protons_charm,
                       Particles& protons_had,
                       Particles& lambda,
                       bool cBaryon = false) {
  for (const Particle& p : parent.children()) {
    if (p.abspid() == PID::PROTON) {
      protons_all.push_back(p);
      if (cBaryon)
        protons_charm.push_back(p);
      else
        protons_had.push_back(p);
    }
    else if (p.abspid() == PID::LAMBDA) {
      lambda.push_back(p);
      continue;
    }
    else if (!p.children().empty()) {
      bool cBaryonDec = cBaryon || (PID::isCharmHadron(p.pid()) && p.abspid() % 2 == 0);
      findDecayProducts(p, protons_all, protons_charm, protons_had, lambda, cBaryonDec);
    }
  }
}


/// 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)) {
    Particles protons[3], lambda;
    findDecayProducts(ups, protons[0], protons[1], protons[2], lambda);
    LorentzTransform boost;
    if (ups.p3().mod() > 1 * MeV) {
      boost = LorentzTransform::mkFrameTransformFromBeta(ups.mom().betaVec());
    }
    for (const Particle& p : protons[0]) {
      double pcm = boost.transform(p.mom()).p3().mod();
      _h_spect[0]->fill(pcm);
    }
    for (const Particle& p : lambda) {
      double pcm = boost.transform(p.mom()).p3().mod();
      _h_spect[1]->fill(pcm);
    }
    for (unsigned int ix = 0; ix < 2; ++ix) {
      for (const Particle& p : protons[ix + 1]) {
        double pcm = boost.transform(p.mom()).p3().mod();
        _h_flav[ix]->fill(pcm);
      }
    }
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  normalize(_h_spect, 1.0, false);
  normalize(_h_flav, 1.0, false);
}

/// @}


/// @name Histograms
/// @{
Histo1DPtr _h_spect[2], _h_flav[2];
/// @}

};

RIVET_DECLARE_PLUGIN(ARGUS_1992_I334962);

} ```