Rivet analyses referenceSND_2001_I579319Cross section for $e^+e^-2\pi^+2\pi^-$ and $\pi^+\pi^-2\pi^0$ between 1 and 1.4 GeVExperiment: SND (VEPP-2M) Inspire ID: 579319 Status: VALIDATED Authors:
Beam energies: ANY Run details:
Measurement of the cross section for $e^+e^-\to\pi^+2\pi^-$ and $\pi^+\pi^-2\pi^0$ between 1 and 1.4 GeV Source code: SND_2001_I579319.cc 1// -*- C++ -*-
2#include "Rivet/Analysis.hh"
3#include "Rivet/Projections/FinalState.hh"
4
5namespace Rivet {
6
7
8 /// @brief Add a short analysis description here
9 class SND_2001_I579319 : public Analysis {
10 public:
11
12 /// Constructor
13 RIVET_DEFAULT_ANALYSIS_CTOR(SND_2001_I579319);
14
15
16 /// @name Analysis methods
17 /// @{
18
19 /// Book histograms and initialise projections before the run
20 void init() {
21
22 // Initialise and register projections
23 declare(FinalState(), "FS");
24
25 // Book histograms
26 for(unsigned int ix=0;ix<2;++ix) {
27 book(_npion[ix], 1+ix, 1, 1);
28 for (const string& en : _npion[ix].binning().edges<0>()) {
29 const double end = std::stod(en)*GeV;
30 if (isCompatibleWithSqrtS(end)) {
31 _ecms[ix] = en;
32 break;
33 }
34 }
35 }
36 if (_ecms[0].empty() && _ecms[1].empty())
37 MSG_ERROR("Beam energy incompatible with analysis.");
38 }
39
40
41 /// Perform the per-event analysis
42 void analyze(const Event& event) {
43 const FinalState& fs = apply<FinalState>(event, "FS");
44
45 map<long,int> nCount;
46 int ntotal(0);
47 for (const Particle& p : fs.particles()) {
48 nCount[p.pid()] += 1;
49 ++ntotal;
50 }
51 if(ntotal!=4) vetoEvent;
52 if(nCount[-211]==2&&nCount[211]==2)
53 _npion[0]->fill(_ecms[0]);
54 else if(nCount[-211]==1&&nCount[211]==1&&nCount[111]==2)
55 _npion[1]->fill(_ecms[1]);
56 }
57
58
59 /// Normalise histograms etc., after the run
60 void finalize() {
61 for (unsigned int ix=0;ix<2;++ix)
62 scale(_npion[ix], crossSection()/ sumOfWeights() /nanobarn);
63 }
64
65 /// @}
66
67
68 /// @name Histograms
69 /// @{
70 BinnedHistoPtr<string> _npion[2];
71 string _ecms[2];
72 /// @}
73
74
75 };
76
77
78 RIVET_DECLARE_PLUGIN(SND_2001_I579319);
79
80
81}
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