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CLEOII_1994_I373188

Hadronic Mass in $\tau^-\to 3\pi^-2\pi^+\pi^0\nu_\tau$
Experiment: CLEOII (CESR)
Inspire ID: 373188
Status: VALIDATED
Authors:
  • Peter Richardson
References:
  • Phys.Rev.Lett. 73 (1994) 934-938
Beams: * *
Beam energies: ANY
Run details:
  • Tau production, can be any process but original data was in $e^+ e^-$ at the $\Upsilon(4S)$ resonance

Measurement of the invariant mass spectrum of the $K^-\eta$ system in $\tau\to 3\pi^-2\pi^+\pi^0\nu_\tau$ measured by CLEO at CESR.

Source code: CLEOII_1994_I373188.cc
 1// -*- C++ -*-
 2#include "Rivet/Analysis.hh"
 3#include "Rivet/Projections/UnstableParticles.hh"
 4
 5namespace Rivet {
 6
 7
 8  /// @brief tau -> (5pi)-pi0
 9  class CLEOII_1994_I373188 : public Analysis {
10  public:
11
12    /// Constructor
13    RIVET_DEFAULT_ANALYSIS_CTOR(CLEOII_1994_I373188);
14
15
16    /// @name Analysis methods
17    ///@{
18
19    /// Book histograms and initialise projections before the run
20    void init() {
21      declare(UnstableParticles(), "UFS");
22      book(_hist,  1, 1, 1);
23    }
24
25    void findDecayProducts(const Particle & mother,
26                           unsigned int & nstable,
27                           Particles& pim, Particles& pi0) {
28      for(const Particle & p : mother.children()) {
29	long id = p.abspid();
30        if (id == PID::PI0 ) {
31          pi0.push_back(p);
32          ++nstable;
33	}
34        else if (abs(id) == PID::PIPLUS) {
35          pim.push_back(p);
36          ++nstable;
37        }
38        else if ( !p.children().empty() ) {
39          findDecayProducts(p, nstable, pim,pi0);
40        }
41        else
42          ++nstable;
43      }
44    }
45
46    /// Perform the per-event analysis
47    void analyze(const Event& event) {
48      const UnstableParticles& ufs = apply<UnstableParticles>(event, "UFS");
49      for (const Particle& p : ufs.particles(Cuts::abspid==PID::TAU)) {
50        Particles pi0,pim;
51        unsigned int nstable = 0;
52        // find the decay products we want
53        findDecayProducts(p, nstable, pim, pi0);
54        if (nstable != 7) continue;
55	// K eta
56        if (pim.size() == 5 && pi0.size() == 1) {
57	  FourMomentum phad=pi0[0].momentum();
58	  for(const Particle & p2: pim)
59	    phad += p2.momentum();
60	  _hist->fill(phad.mass());
61	}
62      }
63    }
64
65
66    /// Normalise histograms etc., after the run
67    void finalize() {
68      normalize(_hist);
69    }
70
71    ///@}
72
73
74    /// @name Histograms
75    ///@{
76    Histo1DPtr _hist;
77    ///@}
78
79
80  };
81
82
83  RIVET_DECLARE_PLUGIN(CLEOII_1994_I373188);
84
85}