1// -*- C++ -*-
 2#include "Rivet/Analysis.hh"
 3#include "Rivet/Projections/FinalState.hh"
 4
 5namespace Rivet {
 6
 7
 8  /// @brief gamma gamma -> K+K-
 9  class BELLE_2003_I629334 : public Analysis {
10  public:
11
12    /// Constructor
13    RIVET_DEFAULT_ANALYSIS_CTOR(BELLE_2003_I629334);
14
15
16    /// @name Analysis methods
17    ///@{
18
19    /// Book histograms and initialise projections before the run
20    void init() {
21      // Final state
22      declare(FinalState(),"FS");
23      // check CMS energy in range
24      if (sqrtS()<1.4*GeV || sqrtS()>2.4*GeV)
25        throw Error("Invalid CMS energy for BELLE_2003_I629334");
26      // bin for the angle plots
27      int ibin = (sqrtS()-1.40)/0.04;
28      book(_h_cTheta,2+ibin/4,1,ibin%4+1);
29      book(_cK, "/TMP/nK");
30    }
31
32
33    /// Perform the per-event analysis
34    void analyze(const Event& event) {
35      Particles part = apply<FinalState>(event,"FS").particles();
36      if (part.size()!=2) vetoEvent;
37      double cTheta(0.);
38      bool foundP(false),foundM(false);
39      for (const Particle& p : part) {
40        if (p.pid()==PID::KPLUS) {
41          foundP=true;
42          cTheta = abs(p.momentum().z()/p.momentum().p3().mod());
43        }
44        else if (p.pid()==PID::KMINUS)
45          foundM=true;
46      }
47      if (!foundP || !foundM) vetoEvent;
48      if (cTheta<=0.6)    _cK->fill();
49      if (_h_cTheta ) _h_cTheta ->fill(cTheta);
50    }
51
52
53    /// Normalise histograms etc., after the run
54    void finalize() {
55      double fact = crossSection()/nanobarn/sumOfWeights();
56      if (_h_cTheta ) scale(_h_cTheta ,fact);
57      double sigma = _cK->val()*fact;
58      double error = _cK->err()*fact;
59      Estimate1DPtr mult;
60      book(mult, 1, 1, 1);
61      for (auto& b : mult->bins()) {
62        if (inRange(sqrtS(), b.xMin(), b.xMax())) {
63          b.set(sigma, error);
64        }
65      }
66    }
67
68    ///@}
69
70
71    /// @name Histograms
72    ///@{
73    Histo1DPtr _h_cTheta;
74    CounterPtr _cK;
75    ///@}
76
77
78  };
79
80
81  RIVET_DECLARE_PLUGIN(BELLE_2003_I629334);
82
83}