Rivet analyses

title: ARGUS_1997_I440304

Spectrum for $\Lambda_c^+(2595)$ production at 10.4 GeV

Experiment: ARGUS (DORIS)

Inspire ID: 440304

Status: VALIDATED

Authors: none listed

References: - Phys.Lett. B402 (1997) 207-212

Beams: e+ e-

Beam energies: (5.2, 5.2)GeV

Run details: - e+e- to hadrons

Spectrum for $\Lambda_c^+(2595)$ production at 10.4 GeV measured by ARGUS.

Source code:ARGUS_1997_I440304.cc

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

include "Rivet/Analysis.hh"

include "Rivet/Projections/Beam.hh"

include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {

/// @brief Excited Lambda_c spectra class ARGUS_1997_I440304 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(ARGUS_1997_I440304);


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

/// Book histograms and initialise projections before the run
void init() {
  // projections
  declare(Beam(), "Beams");
  declare(UnstableParticles(), "UFS");
  // book histos
  book(_h_rate1, "TMP/tot_1", refData(1, 1, 1));
  book(_h_rate2, "TMP/tot_2", refData(1, 2, 1));
  book(_h_x, 2, 1, 1);
}


void findDecayProducts(Particle parent, Particles& Lambda_c, Particles& pions, unsigned int& nstable) {
  for (const Particle& p : parent.children()) {
    if (p.abspid() == 4122) {
      Lambda_c.push_back(p);
      ++nstable;
    }
    else if (p.abspid() == PID::PIPLUS) {
      pions.push_back(p);
      ++nstable;
    }
    else if (!p.children().empty())
      findDecayProducts(p, Lambda_c, pions, nstable);
    else
      ++nstable;
  }
}

/// Perform the per-event analysis
void analyze(const Event& event) {
  static const int id2595 = 102142;
  // Get beams and average beam momentum
  const ParticlePair& beams = apply<Beam>(event, "Beams").beams();
  const double Emax = (beams.first.p3().mod() + beams.second.p3().mod()) / 2.0;
  const double Pmax = sqrt(sqr(Emax) - sqr(2.595));
  const UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");
  for (const Particle& p : ufs.particles(Cuts::abspid == id2595)) {
    // spectrum
    double xp = p.momentum().p3().mod() / Pmax;
    _h_x->fill(xp);
    Particles Lambda_c, pions;
    unsigned int nstable(0);
    findDecayProducts(p, Lambda_c, pions, nstable);
    if (nstable == 3 && pions.size() == 2 && Lambda_c.size() == 1) {
      _h_rate1->fill(xp);
      _h_rate2->fill(xp);
    }
  }
}


/// Normalise histograms etc., after the run
void finalize() {
  normalize(_h_x);
  // br for lambda_c mode from pdg 2018
  double br = 0.0623;
  scale(_h_rate1, br * crossSection() / sumOfWeights() / picobarn);
  scale(_h_rate2, br * crossSection() / sumOfWeights() / picobarn);
  Estimate1DPtr tmp;
  book(tmp, 1, 1, 1);
  barchart(_h_rate1, tmp);
  book(tmp, 1, 2, 1);
  barchart(_h_rate2, tmp);
}

/// @}


/// @name Histograms
/// @{
Histo1DPtr _h_x, _h_rate1, _h_rate2;
/// @}

};

RIVET_DECLARE_PLUGIN(ARGUS_1997_I440304);

} ```