Rivet analyses referenceBABAR_2007_I722710$B^0\to\eta^\prime K^{*0}$ decaysExperiment: BABAR (PEP-II) Inspire ID: 722710 Status: VALIDATED NOHEPDATA Authors:
Beam energies: ANY Run details:
Measurement of the $K^{*0}$ mass and helicity angle distributions for $B^0\to\eta^\prime K^{*0}$ by Babar. The data was read from the plots in the paper which are however background subtracted and efficiency corrected. Source code: BABAR_2007_I722710.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 B0 -> K*0 eta'
10 class BABAR_2007_I722710 : public Analysis {
11 public:
12
13 /// Constructor
14 RIVET_DEFAULT_ANALYSIS_CTOR(BABAR_2007_I722710);
15
16
17 /// @name Analysis methods
18 /// @{
19
20 /// Book histograms and initialise projections before the run
21 void init() {
22 // projection
23 UnstableParticles ufs = UnstableParticles(Cuts::abspid==511);
24 declare(ufs, "UFS");
25 DecayedParticles B0(ufs);
26 B0.addStable(PID::ETAPRIME);
27 declare(B0, "B0");
28 // histograms
29 for(unsigned int ix=0;ix<2;++ix)
30 book(_h[ix],ix+1,1,1);
31 }
32
33
34 /// Perform the per-event analysis
35 void analyze(const Event& event) {
36 static const map<PdgId,unsigned int> & mode = { { 321,1},{-211,1}, { 331,1}};
37 static const map<PdgId,unsigned int> & modeCC = { {-321,1},{ 211,1}, { 331,1}};
38 DecayedParticles B0 = apply<DecayedParticles>(event, "B0");
39 // loop over particles
40 for(unsigned int ix=0;ix<B0.decaying().size();++ix) {
41 int sign = 1;
42 if (B0.decaying()[ix].pid()>0 && B0.modeMatches(ix,3,mode)) {
43 sign=1;
44 }
45 else if (B0.decaying()[ix].pid()<0 && B0.modeMatches(ix,3,modeCC)) {
46 sign=-1;
47 }
48 else
49 continue;
50 const Particle & Kp = B0.decayProducts()[ix].at( sign*321)[0];
51 const Particle & pim = B0.decayProducts()[ix].at(-sign*211)[0];
52 double mKpi = (Kp.momentum()+pim.momentum()).mass();
53 if(mKpi<.755 || mKpi>1.305) continue;
54 _h[0]->fill(mKpi);
55 // boost to b rest frame
56 LorentzTransform boost1 = LorentzTransform::mkFrameTransformFromBeta(B0.decaying()[ix].momentum().betaVec());
57 FourMomentum pK = boost1.transform(Kp.momentum());
58 FourMomentum ppi = boost1.transform(pim.momentum());
59 FourMomentum pKS = pK+ppi;
60 LorentzTransform boost2 = LorentzTransform::mkFrameTransformFromBeta(pKS.betaVec());
61 Vector3 axis = pKS.p3().unit();
62 _h[1]->fill(axis.dot(boost2.transform(pK).p3().unit()));
63 }
64 }
65
66
67 /// Normalise histograms etc., after the run
68 void finalize() {
69 for(unsigned int ix=0;ix<2;++ix)
70 normalize(_h[ix],1.,false);
71 }
72
73 /// @}
74
75
76 /// @name Histograms
77 /// @{
78 Histo1DPtr _h[2];
79 /// @}
80
81
82 };
83
84
85 RIVET_DECLARE_PLUGIN(BABAR_2007_I722710);
86
87}
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