Rivet analyses

Spectrum for Λc+(2595) and Λc+(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 Λc+(2595) and Λc+(2625) production at 10.58 GeV measured by CLEOII.

Source code:CLEOII_1994_I381696.cc

// -*- 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);

}