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 D0 -> KS0 pi+ pi-
10  class CLEO_2003_I633196 : public Analysis {
11  public:
12
13    /// Constructor
14    RIVET_DEFAULT_ANALYSIS_CTOR(CLEO_2003_I633196);
15
16
17    /// @name Analysis methods
18    /// @{
19
20    /// Book histograms and initialise projections before the run
21    void init() {
22
23      // Initialise and register projections
24      UnstableParticles ufs = UnstableParticles(Cuts::abspid==421);
25      declare(ufs, "UFS");
26      DecayedParticles D0(ufs);
27      D0.addStable(PID::PI0);
28      D0.addStable(PID::K0S);
29      D0.addStable(PID::ETA);
30      D0.addStable(PID::ETAPRIME);
31      declare(D0, "D0");
32
33      // Histograms
34      book(_h_Kpim,1,1,1);
35      book(_h_pipi,1,1,2);
36      book(_h_Kpip,1,1,3);
37      book(_dalitz, "dalitz",50,0.,3.,50,0.,2.);
38    }
39
40    /// Perform the per-event analysis
41    void analyze(const Event& event) {
42      // define the decay mode
43      static const map<PdgId,unsigned int> & mode   = { { 310,1}, { 211,1},{-211,1}};
44      DecayedParticles D0 = apply<DecayedParticles>(event, "D0");
45      // loop over particles
46      for(unsigned int ix=0;ix<D0.decaying().size();++ix) {
47	if (!D0.modeMatches(ix,3,mode) ) continue;
48	int sign = D0.decaying()[ix].pid()/421;
49	const Particles & pip= D0.decayProducts()[ix].at( sign*211);
50	const Particles & pim= D0.decayProducts()[ix].at(-sign*211);
51	const Particles & K0 = D0.decayProducts()[ix].at( 310);
52	double mminus = (pim[0].momentum()+K0[0].momentum() ).mass2();
53	double mplus  = (pip[0].momentum()+K0[0].momentum() ).mass2();
54	double mpipi  = (pip[0].momentum()+pim[0].momentum()).mass2();
55	_h_Kpip->fill(mplus);
56	_h_Kpim->fill(mminus);
57	_h_pipi->fill(mpipi);
58	_dalitz->fill(mminus,mpipi); 
59      }
60    }
61
62
63    /// Normalise histograms etc., after the run
64    void finalize() {
65      normalize(_h_Kpip);
66      normalize(_h_pipi);
67      normalize(_h_Kpim);
68      normalize(_dalitz);
69    }
70
71    /// @}
72
73
74    /// @name Histograms
75    /// @{
76    Histo1DPtr _h_Kpim,_h_pipi,_h_Kpip;
77    Histo2DPtr _dalitz;
78    /// @}
79
80
81  };
82
83
84  RIVET_DECLARE_PLUGIN(CLEO_2003_I633196);
85
86}