1// -*- C++ -*-
 2#include "Rivet/Analysis.hh"
 3#include "Rivet/Projections/FinalState.hh"
 4
 5namespace Rivet {
 6
 7
 8  /// @brief gamma gamma -> pi+pi-/K+ K-
 9  class MARKII_1986_I220003 : public Analysis {
10  public:
11
12    /// Constructor
13    RIVET_DEFAULT_ANALYSIS_CTOR(MARKII_1986_I220003);
14
15
16    /// @name Analysis methods
17    ///@{
18
19    /// Book histograms and initialise projections before the run
20    void init() {
21      declare(FinalState(),"FS");
22      // check CMS energy in range
23      if (sqrtS()<1.5*GeV || sqrtS()>5*GeV)
24        throw Error("Invalid CMS energy for MARKII_1986_I220003");
25      book(_cPiK[0], "/TMP/nPiK_0");
26      book(_cPiK[1], "/TMP/nPiK_1");
27    }
28
29    /// Perform the per-event analysis
30    void analyze(const Event& event) {
31      Particles part = apply<FinalState>(event,"FS").particles();
32      if (part.size()!=2) vetoEvent;
33      if (part[0].pid()!=-part[1].pid()) vetoEvent;
34      double cTheta(0.);
35      bool foundPi(false),foundK(false);
36      for (const Particle & p : part) {
37        if (p.pid()==PID::PIPLUS) {
38          foundPi=true;
39          cTheta = abs(p.momentum().z()/p.momentum().p3().mod());
40        }
41        else if (p.pid()==PID::KPLUS) {
42          foundK=true;
43          cTheta = abs(p.momentum().z()/p.momentum().p3().mod());
44        }
45      }
46      if (!foundPi && !foundK) vetoEvent;
47      if (cTheta>0.5) vetoEvent;
48      if (cTheta>0.3)
49        _cPiK[1]->fill();
50      else
51        _cPiK[0]->fill();
52    }
53
54    /// Normalise histograms etc., after the run
55    void finalize() {
56      double fact = crossSection()/nanobarn/sumOfWeights();
57      for (unsigned int ix=0;ix<2;++ix) {
58        double sigma = _cPiK[ix]->val()*fact;
59        double error = _cPiK[ix]->err()*fact;
60        Estimate1DPtr cross;
61        book(cross, 1, 1, 1+ix);
62        for (auto& b : cross->bins()) {
63          if (inRange(sqrtS(), b.xMin(), b.xMax())) {
64            b.set(sigma, error);
65          }
66        }
67      }
68    }
69
70    ///@}
71
72
73    /// @name Histograms
74    ///@{
75    CounterPtr _cPiK[2];
76    ///@}
77
78
79  };
80
81
82  RIVET_DECLARE_PLUGIN(MARKII_1986_I220003);
83
84}