rivet is hosted by Hepforge, IPPP Durham

Rivet analyses reference

BELLE_2009_I810744

Pion Mass Spectrum in $\Upsilon(4S)\to\Upsilon(1S)\pi^+\pi^-$
Experiment: BELLE (KEKB)
Inspire ID: 810744
Status: VALIDATED
Authors:
  • Peter Richardson
References:
  • Phys.Rev. D79 (2009) 051103
Beams: * *
Beam energies: ANY
Run details:
  • Any process producing Upsilon(4S), original e+e-

Measurement of the $\pi^+\pi^-$ mass Spectrum in $\Upsilon(4S)\to\Upsilon(1S)\pi^+\pi^-$ decays.

Source code: BELLE_2009_I810744.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
// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {


  /// @brief Upsilon(4S) -> Upsilon(1S) pi+pi-
  class BELLE_2009_I810744 : public Analysis {
  public:

    /// Constructor
    DEFAULT_RIVET_ANALYSIS_CTOR(BELLE_2009_I810744);


    /// @name Analysis methods
    //@{

    /// Book histograms and initialise projections before the run
    void init() {

      // Initialise and register projections
      declare(UnstableParticles(),"UFS");
      book(_hist, 1, 1, 1);

    }

    void findDecayProducts(const Particle & mother,
			   unsigned int & nstable,
			   Particles& pip, Particles& pim,
			   Particles & onium) {
      for(const Particle & p : mother.children()) {
        int id = p.pid();
      	if ( id == PID::PIMINUS) {
	  pim.push_back(p);
	  ++nstable;
	}
       	else if (id == PID::PIPLUS) {
       	  pip.push_back(p);
       	  ++nstable;
       	}
       	else if (id == PID::PI0) {
       	  ++nstable;
       	}
	else if (id==553) {
	  onium.push_back(p);
	  ++nstable;
	}
	else if ( !p.children().empty() ) {
	  findDecayProducts(p,nstable,pip,pim,onium);
	}
	else
	  ++nstable;
      }
    }
    
    /// Perform the per-event analysis
    void analyze(const Event& event) {
      // loop over unstable particles
      for(const Particle& ups : apply<UnstableParticles>(event, "UFS").particles(Cuts::pid==300553)) {
	unsigned int nstable(0);
	Particles pip, pim, onium;
	findDecayProducts(ups,nstable,pip,pim,onium);
	// check for onium
	if(onium.size() !=1 || nstable !=3) continue;
	// check for pipi
	if( ! (pip.size()==1 && pim.size() ==1) ) continue;
	FourMomentum q = pip[0].momentum()+pim[0].momentum();
	_hist->fill(q.mass());
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      normalize(_hist);
    }

    //@}


    /// @name Histograms
    //@{
    Histo1DPtr _hist;
    //@}


  };


  DECLARE_RIVET_PLUGIN(BELLE_2009_I810744);

}