1// -*- C++ -*-
 2#include "Rivet/Analysis.hh"
 3#include "Rivet/Projections/FinalState.hh"
 4
 5namespace Rivet {
 6
 7
 8  /// @brief gamma gamma -> pi+pi-
 9  class VENUS_1995_I392360 : public Analysis {
10  public:
11
12    /// Constructor
13    RIVET_DEFAULT_ANALYSIS_CTOR(VENUS_1995_I392360);
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 (!inRange(sqrtS(), 1*GeV, 1.5*GeV)) {
25        throw Error("Invalid CMS energy for VENUS_1995_I392360");
26      }
27      // bin for the angle plots
28      int ibin = (sqrtS()-1.0)/0.05 + 2;
29      book(_h_cTheta, ibin, 1, 1);
30      book(_cPi, "/TMP/nPi");
31      _cmax = ibin>2 ? 0.6 : 0.4;
32      if (ibin == 2)  _axis = YODA::Axis<double>(6, 0.0, 0.6);
33      else            _axis = YODA::Axis<double>(4, 0.0, 0.4);
34    }
35
36
37    /// Perform the per-event analysis
38    void analyze(const Event& event) {
39      if (_edges.empty())  _edges = _h_cTheta->xEdges();
40      Particles part = apply<FinalState>(event, "FS").particles();
41      if (part.size()!=2) vetoEvent;
42      double cTheta(0.);
43      bool foundP(false),foundM(false);
44      for (const Particle& p : part) {
45        if (p.pid()==PID::PIPLUS) {
46          foundP = true;
47          cTheta = abs(p.momentum().z()/p.momentum().p3().mod());
48        }
49        else if (p.pid()==PID::PIMINUS)
50          foundM = true;
51      }
52      if (!foundP || !foundM) vetoEvent;
53      if (cTheta<=_cmax)    _cPi->fill();
54      if (_h_cTheta )  _h_cTheta->fill(map2string(cTheta));
55    }
56
57    string map2string(const double value) const {
58      const size_t idx = _axis.index(value) - 1;
59      if (idx < _edges.size())  return _edges[idx];
60      return "OTHER";
61    }
62
63    /// Normalise histograms etc., after the run
64    void finalize() {
65      const double fact = crossSection()/nanobarn/sumOfWeights();
66      if (_h_cTheta ) scale(_h_cTheta, fact);
67      scale(_cPi, fact);
68      BinnedEstimatePtr<string> mult;
69      book(mult, 1, 1, 1);
70      for (auto& b : mult->bins()) {
71        const double Ecm = std::stod(b.xEdge());
72        if (isCompatibleWithSqrtS(sqrtS()/GeV, Ecm)) {
73          b.set(_cPi->val(), _cPi->err());
74        }
75      }
76    }
77
78    ///@}
79
80
81    /// @name Histograms
82    ///@{
83    BinnedHistoPtr<string> _h_cTheta;
84    CounterPtr _cPi;
85    double _cmax;
86    YODA::Axis<double> _axis;
87    vector<string> _edges;
88    ///@}
89
90
91  };
92
93
94  RIVET_DECLARE_PLUGIN(VENUS_1995_I392360);
95
96}