Rivet analyses

Baryon spectra in Υ(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, Λ_c⁺, Λ and Ξ⁻ momentum spectra in B decays at the Υ(4S) by CLEO.

Source code:`CLEO_1992_I315181.cc`

// -*- 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);

}

Rivet analyses

Baryon spectra in Υ(4S) decays

Source code:CLEO_1992_I315181.cc

Source code:`CLEO_1992_I315181.cc`