Rivet analyses referenceCMD2_2003_I616446Cross section for $e^+e^-\to\omega\pi^0\to\pi^0\pi^0\gamma$ between 0.92 and 1.38 GeVExperiment: CMD2 (VEPP-2M) Inspire ID: 616446 Status: VALIDATED Authors:
Beam energies: (0.5, 0.5); (0.5, 0.5); (0.5, 0.5); (0.5, 0.5); (0.5, 0.5); (0.5, 0.5); (0.5, 0.5); (0.5, 0.5); (0.5, 0.5); (0.5, 0.5); (0.5, 0.5); (0.6, 0.6); (0.6, 0.6); (0.6, 0.6); (0.6, 0.6); (0.6, 0.6); (0.6, 0.6); (0.6, 0.6); (0.6, 0.6); (0.6, 0.6); (0.6, 0.6); (0.7, 0.7); (0.7, 0.7); (0.7, 0.7); (0.7, 0.7); (0.7, 0.7) GeV Run details:
Measurement of the cross section for $e^+e^-\to\omega\pi^0\to\pi^0\pi^0\gamma$ at energies 0.92 and 1.38 GeV. Beam energy must be specified as analysis option "ENERGY" when rivet-merging samples. Source code: CMD2_2003_I616446.cc 1// -*- C++ -*-
2#include "Rivet/Analysis.hh"
3#include "Rivet/Projections/FinalState.hh"
4#include "Rivet/Projections/UnstableParticles.hh"
5
6namespace Rivet {
7
8
9 /// @brief Add a short analysis description here
10 class CMD2_2003_I616446 : public Analysis {
11 public:
12
13 /// Constructor
14 RIVET_DEFAULT_ANALYSIS_CTOR(CMD2_2003_I616446);
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 declare(UnstableParticles(), "UFS");
26 book(_numOmegaPi, 1, 1, 1);
27 }
28
29
30 void findChildren(const Particle & p,map<long,int> & nRes, int &ncount) {
31 for (const Particle &child : p.children()) {
32 if(child.children().empty()) {
33 nRes[child.pid()]+=1;
34 ++ncount;
35 }
36 else
37 findChildren(child,nRes,ncount);
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 // three particles (pi0 pi0 gamma)
52 if(ntotal!=3) vetoEvent;
53 const FinalState& ufs = apply<FinalState>(event, "UFS");
54 for (const Particle& p : ufs.particles()) {
55 if(p.children().empty()) continue;
56 // find the omega
57 if(p.pid()==223) {
58 map<long,int> nRes;
59 int ncount(0);
60 findChildren(p,nRes,ncount);
61 // only omega to pi0 gamma mode
62 if(ncount!=2) continue;
63 if(nRes[111]!=1 || nRes[22]!=1) continue;
64 // omega pi0
65 if(nCount[111]-nRes[111]==1)
66 _numOmegaPi->fill(round(sqrtS()/MeV));
67 }
68 }
69 }
70
71
72 /// Normalise histograms etc., after the run
73 void finalize() {
74 scale(_numOmegaPi, crossSection()/ sumOfWeights() /nanobarn);
75 }
76
77 /// @name Histograms
78 /// @{
79 BinnedHistoPtr<int> _numOmegaPi;
80 /// @}
81
82 };
83
84
85 RIVET_DECLARE_PLUGIN(CMD2_2003_I616446);
86
87
88}
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