Rivet analyses referenceBELLE_2018_I1663447Mass and angular distributions in $B^+\to K^+\eta\gamma$ decaysExperiment: BELLE (KEKB) Inspire ID: 1663447 Status: VALIDATED NOHEPDATA Authors:
Beam energies: ANY Run details:
Mass and angular distributions in $B^+\to K^+\eta\gamma$ decays. Data were read from the plots in the paper, but are background subtracted and efficiency corrected. Source code: BELLE_2018_I1663447.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 B+ -> K+ eta gamma
10 class BELLE_2018_I1663447 : public Analysis {
11 public:
12
13 /// Constructor
14 RIVET_DEFAULT_ANALYSIS_CTOR(BELLE_2018_I1663447);
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==521);
24 declare(ufs, "UFS");
25 DecayedParticles BP(ufs);
26 BP.addStable(PID::ETA);
27 declare(BP, "BP");
28 for(unsigned int ix=0;ix<2;++ix)
29 for(unsigned int iy=0;iy<2;++iy)
30 book(_h[ix][iy],1+ix,1,1+iy);
31 }
32
33
34 /// Perform the per-event analysis
35 void analyze(const Event& event) {
36 static const map<PdgId,unsigned int> & mode = { { 221,1},{ 321,1}, {22,1}};
37 static const map<PdgId,unsigned int> & modeCC = { { 221,1},{-321,1}, {22,1}};
38 DecayedParticles BP = apply<DecayedParticles>(event, "BP");
39 // loop over particles
40 for(unsigned int ix=0;ix<BP.decaying().size();++ix) {
41 int sign = 1;
42 if (BP.decaying()[ix].pid()>0 && BP.modeMatches(ix,3,mode)) {
43 sign=1;
44 }
45 else if (BP.decaying()[ix].pid()<0 && BP.modeMatches(ix,3,modeCC)) {
46 sign=-1;
47 }
48 else
49 continue;
50 const Particle & Kp = BP.decayProducts()[ix].at( sign*321)[0];
51 const Particle & eta = BP.decayProducts()[ix].at( 221)[0];
52 const Particle & gamma = BP.decayProducts()[ix].at( 22)[0];
53 FourMomentum pKeta = Kp.momentum()+eta.momentum();
54 double mass = pKeta.mass();
55 LorentzTransform boostB = LorentzTransform::mkFrameTransformFromBeta(BP.decaying()[ix].momentum().betaVec());
56 pKeta = boostB.transform(pKeta);
57 LorentzTransform boostKeta = LorentzTransform::mkFrameTransformFromBeta(pKeta.betaVec());
58 FourMomentum pK = boostKeta.transform(boostB.transform(Kp .momentum()));
59 FourMomentum pGamma = boostB.transform(gamma.momentum());
60 double cTheta = pK.p3().unit().dot(pGamma.p3().unit());
61 for(unsigned int iy=0;iy<2;++iy) {
62 _h[0][iy]->fill(cTheta);
63 _h[1][iy]->fill(mass );
64 }
65 }
66 }
67
68
69 /// Normalise histograms etc., after the run
70 void finalize() {
71 for(unsigned int ix=0;ix<2;++ix)
72 for(unsigned int iy=0;iy<2;++iy)
73 normalize(_h[ix][iy],1.,false);
74 }
75
76 /// @}
77
78
79 /// @name Histograms
80 /// @{
81 Histo1DPtr _h[2][2];
82 /// @}
83
84
85 };
86
87
88 RIVET_DECLARE_PLUGIN(BELLE_2018_I1663447);
89
90}
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