1// -*- C++ -*-
 2#include "Rivet/Analysis.hh"
 3#include "Rivet/Projections/UnstableParticles.hh"
 4#include "Rivet/Projections/DecayedParticles.hh"
 5
 6namespace Rivet {
 7
 8
 9  /// @brief tau -> 3 pi
10  class ARGUS_1992_I339268 : public Analysis {
11  public:
12
13    /// Constructor
14    RIVET_DEFAULT_ANALYSIS_CTOR(ARGUS_1992_I339268);
15
16
17    /// @name Analysis methods
18    /// @{
19
20    /// Book histograms and initialise projections before the run
21    void init() {
22      // Initialise and register projections
23      UnstableParticles ufs(Cuts::abspid==15);
24      declare(ufs, "UFS");
25      DecayedParticles TAU(ufs);
26      TAU.addStable(310);
27      TAU.addStable(111);
28      declare(TAU, "TAU");
29      // histos
30      book(_h_mass,1,1,1);
31    }
32
33
34    /// Perform the per-event analysis
35    void analyze(const Event& event) {
36      DecayedParticles TAU = apply<DecayedParticles>(event, "TAU");
37      // loop over particles
38      for (unsigned int ix=0; ix<TAU.decaying().size(); ++ix) {
39      	int sign = TAU.decaying()[ix].pid()>0 ? 1 : -1;
40      	if (!(TAU.modeMatches(ix,4,mode) || TAU.modeMatches(ix,4,modeCC))) {
41          continue;
42        }
43      	const Particles& pip = TAU.decayProducts()[ix].at( 211*sign);
44        const Particles & pim = TAU.decayProducts()[ix].at(-211*sign);
45        double Q2 = (pip[0].mom()+pim[0].mom()+pim[1].mom()).mass2();
46        _h_mass->fill(sqrt(Q2));
47      }
48    }
49
50
51    /// Normalise histograms etc., after the run
52    void finalize() {
53      normalize(_h_mass,1.,false);
54    }
55
56    /// @}
57
58
59    /// @name Histograms
60    /// @{
61    Histo1DPtr _h_mass;
62    const map<PdgId,unsigned int> mode   = { {-211,2}, { 211,1}, { 16,1}};
63    const map<PdgId,unsigned int> modeCC = { { 211,2}, {-211,1}, {-16,1}};
64    /// @}
65
66
67  };
68
69
70  RIVET_DECLARE_PLUGIN(ARGUS_1992_I339268);
71
72}