Rivet analyses

title: CLEOII_1994_I381696

Spectrum for $\Lambda_c^+(2595)$ and $\Lambda_c^+(2625)$ production at 10.58 GeV

Experiment: CLEOII (CESR)

Inspire ID: 381696

Status: VALIDATED

Authors: - Peter Richardson

References: - Phys.Rev.Lett. 74 (1995) 3331-3335

Beams: e+ e-

Beam energies: (5.3, 5.3)GeV

Run details: - e+e- to hadrons

Spectrum for $\Lambda_c^+(2595)$ and $\Lambda_c^+(2625)$ production at 10.58 GeV measured by CLEOII.

Source code:CLEOII_1994_I381696.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 CLEOII_1994_I381696 : public Analysis { public:

/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(CLEOII_1994_I381696);


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

/// Book histograms and initialise projections before the run
void init() {
  // projections
  declare(Beam(), "Beams");
  declare(UnstableParticles(), "UFS");
  // book histos
  book(_h_2595, 5, 1, 1);
  book(_h_2625, 6, 1, 1);
  book(_r_2595, 4, 1, 1);
  book(_r_2625, 4, 1, 2);
  book(_c_lam, "TMP/c_lam");
}


void findDecayProducts(const Particle& mother,
                       unsigned int& npip,
                       unsigned int& npim,
                       unsigned int& nlam) {
  for (const Particle& p : mother.children()) {
    if (p.abspid() == 4122)
      ++nlam;
    else if (p.pid() == 211)
      ++npip;
    else if (p.pid() == -211)
      ++npim;
    else if (!p.children().empty())
      findDecayProducts(p, npip, npim, nlam);
  }
}

/// Perform the per-event analysis
void analyze(const Event& event) {
  static const int id2595 = 102142;
  static const int id2625 = 102144;
  // 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 UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");
  for (const Particle& p : ufs.particles(Cuts::abspid == id2595 or Cuts::abspid == id2625)) {
    unsigned int nlam(0), npip(0), npim(0);
    findDecayProducts(p, npip, npim, nlam);
    bool isDecay = npip == 1 && npim == 1 && nlam == 1;
    // spectrum
    if (p.abspid() == id2595) {
      double Pmax = sqrt(sqr(Emax) - sqr(2.595));
      double xp = p.momentum().p3().mod() / Pmax;
      _h_2595->fill(xp);
      if (isDecay) _r_2595->fill(10.55);
    }
    else {
      double Pmax = sqrt(sqr(Emax) - sqr(2.625));
      double xp = p.momentum().p3().mod() / Pmax;
      _h_2625->fill(xp);
      if (isDecay) _r_2625->fill(10.55);
    }
  }
  unsigned int nlam = ufs.particles(Cuts::abspid == 4122).size();
  _c_lam->fill(nlam);
}


/// Normalise histograms etc., after the run
void finalize() {
  normalize(_h_2595);
  normalize(_h_2625);
  scale(_r_2595, 0.06 / *_c_lam);
  scale(_r_2625, 0.06 / *_c_lam);
}

/// @}


/// @name Histograms
/// @{
Histo1DPtr _h_2595, _h_2625;
Histo1DPtr _r_2595, _r_2625;
CounterPtr _c_lam;
/// @}

};

RIVET_DECLARE_PLUGIN(CLEOII_1994_I381696);

} ```