rivet is hosted by Hepforge, IPPP Durham

Rivet analyses reference

BABAR_2006_I719581

Decay asymmetries in the decay of $\Omega^-$ baryons produced in $\Xi^0_c$ and $\Omega_c^0$ decays
Experiment: BABAR (PEP-II)
Inspire ID: 719581
Status: VALIDATED
Authors:
  • Peter Richardson
References:
  • Phys.Rev.Lett. 97 (2006) 112001
Beams: * *
Beam energies: ANY
Run details:
  • Any process producing Xi_c0 and Omega_c0 baryons

Measurement of the decay asymmetries in $\Xi^0_c\to\Omega^-K^+$ and $\Omega^=_c\to\Omega^-\pi^+$ by the BaBar experiment. In both cases the decay mode $\Omega^-\to\Lambda^0K^-$ was used. This analysis is useful for testing spin correlations in hadron decays.

Source code: BABAR_2006_I719581.cc
  1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {


  /// @brief Omega decay asymmetries
  class BABAR_2006_I719581 : public Analysis {
  public:

    /// Constructor
    DEFAULT_RIVET_ANALYSIS_CTOR(BABAR_2006_I719581);


    /// @name Analysis methods
    //@{

    /// Book histograms and initialise projections before the run
    void init() {
      
      // Initialise and register projections
      declare(UnstableParticles(), "UFS" );
      // Book histograms
      book(_h_ctheta_xic   ,1,1,1);
      book(_h_ctheta_omegac,2,1,1);
    }


    /// Perform the per-event analysis
    void analyze(const Event& event) {
      // loop over Xi_c0 baryons and Omega_c0 baryons
      for(const Particle& baryon : apply<UnstableParticles>(event, "UFS").particles(Cuts::abspid==4132 || Cuts::abspid==4332 )) {
	int sign = baryon.pid()/baryon.abspid();
	if(baryon.children().size()!=2) continue;
	Particle baryon1,meson1;
	if(baryon.abspid()==4132) {
	  if(baryon.children()[0].pid()==sign*3334 && 
	     baryon.children()[1].pid()==sign*321) {
	    baryon1 = baryon.children()[0];
	    meson1  = baryon.children()[1];
	  }
	  else if(baryon.children()[1].pid()==sign*3332 && 
		  baryon.children()[0].pid()==sign*321) {
	    baryon1 = baryon.children()[1];
	    meson1  = baryon.children()[0];
	  }
	  else
	    continue;
	}
	else {
	  if(baryon.children()[0].pid()==sign*3334 && 
	     baryon.children()[1].pid()==sign*211) {
	    baryon1 = baryon.children()[0];
	    meson1  = baryon.children()[1];
	  }
	  else if(baryon.children()[1].pid()==sign*3334 && 
		  baryon.children()[0].pid()==sign*211) {
	    baryon1 = baryon.children()[1];
	    meson1  = baryon.children()[0];
	  }
	  else
	    continue;
	}
	Particle baryon2,meson2;
	if(baryon1.children()[0].pid()== sign*3122 && 
	   baryon1.children()[1].pid()==-sign*321) {
	  baryon2 = baryon1.children()[0];
	  meson2  = baryon1.children()[1];
	}
	else if(baryon1.children()[1].pid()== sign*3122 && 
		baryon1.children()[0].pid()==-sign*321) {
	  baryon2 = baryon1.children()[1];
	  meson2  = baryon1.children()[0];
	}
	else
	  continue;
	// first boost to the Xic/Omegac rest frame
	LorentzTransform boost1 = LorentzTransform::mkFrameTransformFromBeta(baryon.momentum().betaVec());
	FourMomentum pbaryon1 = boost1.transform(baryon1.momentum());
	FourMomentum pbaryon2 = boost1.transform(baryon2.momentum());
	// to omega rest frame
	LorentzTransform boost2 = LorentzTransform::mkFrameTransformFromBeta(pbaryon1.betaVec());
	Vector3 axis = pbaryon1.p3().unit();
	FourMomentum pp = boost2.transform(pbaryon2);
	// calculate angle
	double cTheta = pp.p3().unit().dot(axis);
	if(baryon.abspid()==4132)
	  _h_ctheta_xic->fill(cTheta,1.);
	else 
	  _h_ctheta_omegac->fill(cTheta,1.);	
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {

      normalize(_h_ctheta_xic);
      normalize(_h_ctheta_omegac);
    }

    //@}


    /// @name Histograms
    //@{
    Histo1DPtr _h_ctheta_xic,_h_ctheta_omegac;
    //@}


  };


  // The hook for the plugin system
  DECLARE_RIVET_PLUGIN(BABAR_2006_I719581);


}