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ARGUS_1992_I334962

Proton and $\Lambda$ momentum spectrum in B decays
Experiment: ARGUS (DORIS)
Inspire ID: 334962
Status: VALIDATED NOHEPDATA
Authors:
  • Peter Richardson
References:
  • Z.Phys.C 56 (1992) 1-6
Beams: * *
Beam energies: ANY
Run details:
  • Any processs producing Upslion(4S), originally e+e-

Measurement of the proton and $\Lambda$ momentum spectrum in B decays by ARGUS. The corrected data were read from the figures in the paper.

Source code: ARGUS_1992_I334962.cc
 1// -*- C++ -*-
 2#include "Rivet/Analysis.hh"
 3#include "Rivet/Projections/UnstableParticles.hh"
 4
 5namespace Rivet {
 6
 7
 8  /// @brief B-> baryons
 9  class ARGUS_1992_I334962 : public Analysis {
10  public:
11
12    /// Constructor
13    RIVET_DEFAULT_ANALYSIS_CTOR(ARGUS_1992_I334962);
14
15
16    /// @name Analysis methods
17    /// @{
18
19    /// Book histograms and initialise projections before the run
20    void init() {
21      // projections
22      declare(UnstableParticles(), "UFS");
23      // histos
24      for (unsigned int ix=0; ix < 2; ++ix) {
25        book(_h_spect[ix],1+ix,1,1);
26        book(_h_flav [ix],3,1,1+ix);
27      }
28    }
29
30    void findDecayProducts(const Particle& parent, Particles& protons_all, Particles& protons_charm,
31                           Particles& protons_had, Particles & lambda, bool cBaryon=false) {
32      for (const Particle& p : parent.children()) {
33       	if (p.abspid() == PID::PROTON) {
34       	  protons_all.push_back(p);
35          if (cBaryon) protons_charm.push_back(p);
36          else         protons_had  .push_back(p);
37        }
38        else if (p.abspid()== PID::LAMBDA) {
39          lambda.push_back(p);
40          continue;
41        }
42        else if (!p.children().empty()) {
43          bool cBaryonDec = cBaryon || ( PID::isCharmHadron(p.pid()) && p.abspid()%2==0);
44          findDecayProducts(p,protons_all,protons_charm,protons_had,lambda,cBaryonDec);
45        }
46      }
47    }
48
49
50    /// Perform the per-event analysis
51    void analyze(const Event& event) {
52      // Find the upsilons
53      for (const Particle& ups : apply<UnstableParticles>(event, "UFS").particles(Cuts::pid==300553)) {
54        Particles protons[3],lambda;
55        findDecayProducts(ups,protons[0],protons[1],protons[2],lambda);
56        LorentzTransform boost;
57        if (ups.p3().mod() > 1*MeV) {
58          boost = LorentzTransform::mkFrameTransformFromBeta(ups.mom().betaVec());
59        }
60        for (const Particle& p : protons[0]) {
61          double pcm = boost.transform(p.mom()).p3().mod();
62          _h_spect[0]->fill(pcm);
63        }
64        for (const Particle& p : lambda) {
65          double pcm = boost.transform(p.mom()).p3().mod();
66          _h_spect[1]->fill(pcm);
67        }
68        for (unsigned int ix=0; ix<2; ++ix) {
69          for (const Particle& p : protons[ix+1]) {
70            double pcm = boost.transform(p.mom()).p3().mod();
71            _h_flav[ix]->fill(pcm);
72          }
73        }
74      }
75    }
76
77
78    /// Normalise histograms etc., after the run
79    void finalize() {
80      normalize(_h_spect, 1.0, false);
81      normalize(_h_flav , 1.0, false);
82    }
83
84    /// @}
85
86
87    /// @name Histograms
88    /// @{
89    Histo1DPtr _h_spect[2], _h_flav[2];
90    /// @}
91
92
93  };
94
95
96  RIVET_DECLARE_PLUGIN(ARGUS_1992_I334962);
97
98}