Rivet analyses referenceSND_2002_I587084Cross section for $e^+e^-\to\pi^0\pi^0\gamma$ at energies between 0.6 and 0.97 GeV.Experiment: SND (VEPP-2M) Inspire ID: 587084 Status: VALIDATED Authors:
Beam energies: ANY Run details:
1// -*- C++ -*-
2#include "Rivet/Analysis.hh"
3#include "Rivet/Projections/FinalState.hh"
4
5
6namespace Rivet {
7
8
9 /// @brief Add a short analysis description here
10 class SND_2002_I587084 : public Analysis {
11 public:
12
13 /// Constructor
14 RIVET_DEFAULT_ANALYSIS_CTOR(SND_2002_I587084);
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 declare(FinalState(), "FS");
25 book(_numPiPiGamma, "TMP/PiPiGamma");
26
27 }
28
29
30 /// Perform the per-event analysis
31 void analyze(const Event& event) {
32
33 const FinalState& fs = apply<FinalState>(event, "FS");
34
35 map<long,int> nCount;
36 int ntotal(0);
37 for (const Particle& p : fs.particles()) {
38 nCount[p.pid()] += 1;
39 ++ntotal;
40 }
41 // three particles (pi0 pi0 gamma)
42 if(ntotal!=3) vetoEvent;
43 if(nCount[111]==2 && nCount[22]==1)
44 _numPiPiGamma->fill();
45 }
46
47
48 /// Normalise histograms etc., after the run
49 void finalize() {
50
51 double sigma = _numPiPiGamma->val();
52 double error = _numPiPiGamma->err();
53 sigma *= crossSection()/ sumOfWeights() /nanobarn;
54 error *= crossSection()/ sumOfWeights() /nanobarn;
55 Scatter2D temphisto(refData(1, 1, 1));
56 Scatter2DPtr mult;
57 book(mult, 1, 1, 1);
58 for (size_t b = 0; b < temphisto.numPoints(); b++) {
59 const double x = temphisto.point(b).x();
60 pair<double,double> ex = temphisto.point(b).xErrs();
61 pair<double,double> ex2 = ex;
62 if(ex2.first ==0.) ex2. first=0.0001;
63 if(ex2.second==0.) ex2.second=0.0001;
64 if (inRange(sqrtS()/MeV, x-ex2.first, x+ex2.second)) {
65 mult->addPoint(x, sigma, ex, make_pair(error,error));
66 }
67 else {
68 mult->addPoint(x, 0., ex, make_pair(0.,.0));
69 }
70 }
71 }
72
73 //@}
74
75
76 /// @name Histograms
77 //@{
78 CounterPtr _numPiPiGamma;
79 //@}
80
81
82 };
83
84
85 // The hook for the plugin system
86 RIVET_DECLARE_PLUGIN(SND_2002_I587084);
87
88
89}
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