Rivet analyses referenceBELLE_2008_I754089Transversality angles for $\eta_c\to f_2f^{(\prime)}_2$Experiment: BELLE (KEKB) Inspire ID: 754089 Status: VALIDATED NOHEPDATA Authors:
Beam energies: ANY Run details:
Transversality angles for $\eta_c\to f_2f^{(\prime)}_2$. The background subtracted data were read from figure 8 in the paper. Source code: BELLE_2008_I754089.cc 1// -*- C++ -*-
2#include "Rivet/Analysis.hh"
3#include "Rivet/Projections/UnstableParticles.hh"
4#include "Rivet/Projections/DecayedParticles.hh"
5
6namespace Rivet {
7
8
9 /// @brief Transversality angles for $\eta_c\to f_2f^{(\prime)}_2$
10 class BELLE_2008_I754089 : public Analysis {
11 public:
12
13 /// Constructor
14 RIVET_DEFAULT_ANALYSIS_CTOR(BELLE_2008_I754089);
15
16
17 /// @name Analysis methods
18 /// @{
19
20 /// Book histograms and initialise projections before the run
21 void init() {
22 // Initialise and register projections
23 UnstableParticles ufs = UnstableParticles(Cuts::abspid==441);
24 declare(ufs, "UFS");
25 DecayedParticles ETA(ufs);
26 ETA.addStable(225);
27 ETA.addStable(335);
28 declare(ETA, "ETA");
29 // histos
30 for (unsigned int ix=0; ix<2; ++ix) {
31 book(_h[ix],1,1,1+ix);
32 }
33 }
34
35
36 /// Perform the per-event analysis
37 void analyze(const Event& event) {
38 DecayedParticles ETA = apply<DecayedParticles>(event, "ETA");
39 // loop over particles
40 for (unsigned int ix=0; ix<ETA.decaying().size(); ++ix) {
41 int imode=-1;
42 if (ETA.modeMatches(ix,2,mode1)) imode=0;
43 else if (ETA.modeMatches(ix,2,mode2)) imode=1;
44 else {
45 continue;
46 }
47 Vector3 trans[2];
48 bool found=true;
49 LorentzTransform boost1 = LorentzTransform::mkFrameTransformFromBeta(ETA.decaying()[ix].mom().betaVec());
50 Vector3 axis = boost1.transform(ETA.decaying()[ix].children()[0].mom()).p3().unit();
51 for (unsigned int iy=0;iy<ETA.decaying()[ix].children().size();++iy) {
52 int iMeson = ETA.decaying()[ix].children()[iy].pid()==225 ? 211 : 321;
53 if (ETA.decaying()[ix].children()[iy].children().size()!=2) found=false;
54 if (ETA.decaying()[ix].children()[iy].children()[0].pid()!=
55 -ETA.decaying()[ix].children()[iy].children()[1].pid()) found=false;
56 if (ETA.decaying()[ix].children()[iy].children()[0].abspid()!=iMeson) found=false;
57 if (!found) break;
58 FourMomentum pF2 = boost1.transform(ETA.decaying()[ix].children()[iy].mom());
59 LorentzTransform boost2 = LorentzTransform::mkFrameTransformFromBeta(pF2.betaVec());
60 FourMomentum pMeson = boost2.transform(boost1.transform(ETA.decaying()[ix].children()[iy].children()[0].mom()));
61 trans[iy] = pMeson.p3().unit()-pMeson.p3().unit().dot(axis)*axis;
62 }
63 if (!found) continue;
64 const double chi = atan2(trans[0].cross(trans[1]).dot(axis),trans[0].dot(trans[1]));
65 _h[imode]->fill(chi);
66 }
67 }
68
69
70 /// Normalise histograms etc., after the run
71 void finalize() {
72 normalize(_h, 1.0, false);
73 }
74
75 /// @}
76
77
78 /// @name Histograms
79 /// @{
80 Histo1DPtr _h[2];
81 const map<PdgId,unsigned int> mode1 = { { 225,2}};
82 const map<PdgId,unsigned int> mode2 = { { 225,1},{ 335,1}};
83 /// @}
84
85
86 };
87
88
89 RIVET_DECLARE_PLUGIN(BELLE_2008_I754089);
90
91}
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