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 = applyProjection<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	Scatter2D temphisto(refData(1, 1, 1+ix));
61	Scatter2DPtr cross;
62	book(cross, 1, 1, 1+ix);
63	for (size_t b = 0; b < temphisto.numPoints(); b++) {
64	  const double x  = temphisto.point(b).x();
65	  pair<double,double> ex = temphisto.point(b).xErrs();
66	  pair<double,double> ex2 = ex;
67	  if(ex2.first ==0.) ex2. first=0.0001;
68	  if(ex2.second==0.) ex2.second=0.0001;
69	  if (inRange(sqrtS(), x-ex2.first, x+ex2.second)) {
70	    cross->addPoint(x, sigma, ex, make_pair(error,error));
71	  }
72	  else {
73	    cross->addPoint(x, 0., ex, make_pair(0.,.0));
74	  }
75	}
76      }
77    }
78
79    ///@}
80
81
82    /// @name Histograms
83    ///@{
84    CounterPtr _cPiK[2];
85    ///@}
86
87
88  };
89
90
91  RIVET_DECLARE_PLUGIN(MARKII_1986_I220003);
92
93}