Rivet Analyses Reference

BABAR_2007_S7266081

Measurements of Semi-Leptonic Tau Decays into Three Charged Hadrons
Experiment: BaBar (PEP-II)
Inspire ID: 756323
Status: VALIDATED
Authors:
  • Peter Richardson
References:
  • Phys.Rev.Lett.100:011801,2008
  • arXiv: 0707.2981
  • SLAC-R-936
Beams: e+ e-
Beam energies: (3.5, 8.0) GeV
Run details:
  • Tau production, can be any process but original data was in $e^+ e^-$ at the $\Upsilon(4S)$ resonance, with CoM boosts of 8.0 GeV ($e^-$) and 3.5 GeV ($e^+$)

Measurement of tau decays to three charged hadrons using a data sample corresponding to an integrated luminosity of 342 fb$^{-1}$ collected with the BABAR detector at the SLAC PEP-II electron-positron storage ring operating at a center-of-mass energy near 10.58 GeV.

Source code: BABAR_2007_S7266081.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
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/UnstableParticles.hh"

namespace Rivet {


  /// @brief BABAR tau lepton to three charged hadrons
  ///
  /// @author Peter Richardson
  class BABAR_2007_S7266081 : public Analysis {
  public:

    RIVET_DEFAULT_ANALYSIS_CTOR(BABAR_2007_S7266081);


    void init() {
      declare(UnstableParticles(), "UFS");

      book(_hist_pipipi_pipipi , 1, 1, 1);
      book(_hist_pipipi_pipi   , 2, 1, 1);
      book(_hist_Kpipi_Kpipi   , 3, 1, 1);
      book(_hist_Kpipi_Kpi     , 4, 1, 1);
      book(_hist_Kpipi_pipi    , 5, 1, 1);
      book(_hist_KpiK_KpiK     , 6, 1, 1);
      book(_hist_KpiK_KK       , 7, 1, 1);
      book(_hist_KpiK_piK      , 8, 1, 1);
      book(_hist_KKK_KKK       , 9, 1, 1);
      book(_hist_KKK_KK        ,10, 1, 1);

      book(_weight_total, "/TMP/weight_total");
      book(_weight_pipipi, "/TMP/weight_pipipi");
      book(_weight_Kpipi, "/TMP/weight_Kpipi");
      book(_weight_KpiK, "/TMP/weight_KpiK");
      book(_weight_KKK, "/TMP/weight_KKK");

      book(tmp11, 11, 1, 1, true);
      book(tmp12, 12, 1, 1, true);
      book(tmp13, 13, 1, 1, true);
      book(tmp14, 14, 1, 1, true);
    }


    void analyze(const Event& e) {
      // Find the taus
      Particles taus;
      for(const Particle& p : apply<UnstableParticles>(e, "UFS").particles(Cuts::pid==PID::TAU)) {
        _weight_total->fill();
        Particles pip, pim, Kp, Km;
        unsigned int nstable = 0;
        // Find the decay products we want
        findDecayProducts(p, nstable, pip, pim, Kp, Km);
        if (p.pid() < 0) {
          swap(pip, pim);
          swap(Kp, Km );
        }
        if (nstable != 4) continue;
        // pipipi
        if (pim.size() == 2 && pip.size() == 1) {
          _weight_pipipi->fill();
          _hist_pipipi_pipipi->
            fill((pip[0].momentum()+pim[0].momentum()+pim[1].momentum()).mass());
          _hist_pipipi_pipi->
            fill((pip[0].momentum()+pim[0].momentum()).mass());
          _hist_pipipi_pipi->
            fill((pip[0].momentum()+pim[1].momentum()).mass());
        }
        else if (pim.size() == 1 && pip.size() == 1 && Km.size() == 1) {
          _weight_Kpipi->fill();
          _hist_Kpipi_Kpipi->
            fill((pim[0].momentum()+pip[0].momentum()+Km[0].momentum()).mass());
          _hist_Kpipi_Kpi->
            fill((pip[0].momentum()+Km[0].momentum()).mass());
          _hist_Kpipi_pipi->
            fill((pim[0].momentum()+pip[0].momentum()).mass());
        }
        else if (Kp.size() == 1 && Km.size() == 1 && pim.size() == 1) {
          _weight_KpiK->fill();
          _hist_KpiK_KpiK->
            fill((Kp[0].momentum()+Km[0].momentum()+pim[0].momentum()).mass());
          _hist_KpiK_KK->
            fill((Kp[0].momentum()+Km[0].momentum()).mass());
          _hist_KpiK_piK->
            fill((Kp[0].momentum()+pim[0].momentum()).mass());
        }
        else if (Kp.size() == 1 && Km.size() == 2) {
          _weight_KKK->fill();
          _hist_KKK_KKK->
            fill((Kp[0].momentum()+Km[0].momentum()+Km[1].momentum()).mass());
          _hist_KKK_KK->
            fill((Kp[0].momentum()+Km[0].momentum()).mass());
          _hist_KKK_KK->
            fill((Kp[0].momentum()+Km[1].momentum()).mass());
        }
      }
    }


    void finalize() {
      if (_weight_pipipi->val() > 0.) {
        scale(_hist_pipipi_pipipi, 1.0 / *_weight_pipipi);
        scale(_hist_pipipi_pipi  , 0.5 / *_weight_pipipi);
      }
      if (_weight_Kpipi->val() > 0.) {
        scale(_hist_Kpipi_Kpipi  , 1.0 / *_weight_Kpipi);
        scale(_hist_Kpipi_Kpi    , 1.0 / *_weight_Kpipi);
        scale(_hist_Kpipi_pipi   , 1.0 / *_weight_Kpipi);
      }
      if (_weight_KpiK->val() > 0.) {
        scale(_hist_KpiK_KpiK    , 1.0 / *_weight_KpiK);
        scale(_hist_KpiK_KK      , 1.0 / *_weight_KpiK);
        scale(_hist_KpiK_piK     , 1.0 / *_weight_KpiK);
      }
      if (_weight_KKK->val() > 0.) {
        scale(_hist_KKK_KKK      , 1.0 / *_weight_KKK);
        scale(_hist_KKK_KK       , 0.5 / *_weight_KKK);
      }
      tmp11->point(0).setY(100*_weight_pipipi->val()/_weight_total->val(), 100*sqrt(double(_weight_pipipi->val()))/_weight_total->val());
      tmp12->point(0).setY(100*_weight_Kpipi->val()/_weight_total->val(), 100*sqrt(double(_weight_Kpipi->val()))/_weight_total->val());
      tmp13->point(0).setY(100*_weight_KpiK->val()/_weight_total->val(), 100*sqrt(double(_weight_KpiK->val()))/_weight_total->val());
      tmp14->point(0).setY(100*_weight_KKK->val()/_weight_total->val(), 100*sqrt(double(_weight_KKK->val()))/_weight_total->val());
    }


  private:

    Scatter2DPtr tmp11, tmp12, tmp13, tmp14;

    // Histograms
    Histo1DPtr _hist_pipipi_pipipi, _hist_pipipi_pipi;
    Histo1DPtr _hist_Kpipi_Kpipi, _hist_Kpipi_Kpi, _hist_Kpipi_pipi;
    Histo1DPtr _hist_KpiK_KpiK, _hist_KpiK_KK, _hist_KpiK_piK;
    Histo1DPtr _hist_KKK_KKK, _hist_KKK_KK;

    // Weights counters
    CounterPtr _weight_total, _weight_pipipi, _weight_Kpipi, _weight_KpiK, _weight_KKK;


    void findDecayProducts(const Particle &mother,
                           unsigned int & nstable,
                           Particles& pip, Particles& pim,
                           Particles& Kp, Particles& Km) {
      for (const Particle &p : mother.children()) {
        long id = p.pid();
        if (id == PID::PI0 )
          ++nstable;
        else if (id == PID::K0S)
          ++nstable;
        else if (id == PID::PIPLUS) {
          pip.push_back(p);
          ++nstable;
        }
        else if (id == PID::PIMINUS) {
          pim.push_back(p);
          ++nstable;
        }
        else if (id == PID::KPLUS) {
          Kp.push_back(p);
          ++nstable;
        }
        else if (id == PID::KMINUS) {
          Km.push_back(p);
          ++nstable;
        }
        else if (!p.children().empty()) {
          findDecayProducts(p, nstable, pip, pim, Kp, Km);
        }
        else  ++nstable;
      }
    }

  };


  RIVET_DECLARE_ALIASED_PLUGIN(BABAR_2007_S7266081, BABAR_2007_I756323);

}