Rivet analyses referenceBABAR_2004_I626518Helicity angles and polarization in $B^-\to D^{*0}K^{*-}$Experiment: BABAR (PEP-II) Inspire ID: 626518 Status: VALIDATED NOHEPDATA Authors:
Beam energies: ANY Run details:
Measurement of the helicity angles and polarization in $B^-\to D^{*0}K^{*-}$. The data was read from figure 2 in the paper and the background given subtracted. Source code: BABAR_2004_I626518.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- -> D*0 K*-
10 class BABAR_2004_I626518 : public Analysis {
11 public:
12
13 /// Constructor
14 RIVET_DEFAULT_ANALYSIS_CTOR(BABAR_2004_I626518);
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( 423);
27 BP.addStable(-423);
28 BP.addStable( 323);
29 BP.addStable(-323);
30 declare(BP, "BP");
31 // histos
32 for(unsigned int ix=0;ix<2;++ix)
33 for(unsigned int iy=0;iy<2;++iy)
34 book(_h[ix][iy],2,1+ix,1+iy);
35 for(unsigned int ix=0;ix<2;++ix)
36 book(_p[ix],"TMP/p_"+toString(ix+1));
37 }
38
39 bool isK(int id) {
40 return id==321 || id==311 || id==310 || id==130;
41 }
42
43 bool isPi(int id) {
44 return id==211 || id==111;
45 }
46
47 /// Perform the per-event analysis
48 void analyze(const Event& event) {
49 static const map<PdgId,unsigned int> & mode = { {-423,1}, { 323,1}};
50 static const map<PdgId,unsigned int> & modeCC = { { 423,1}, {-323,1}};
51 DecayedParticles BP = apply<DecayedParticles>(event, "BP");
52 // loop over particles
53 for(unsigned int ix=0;ix<BP.decaying().size();++ix) {
54 int sign = 1;
55 if ( BP.decaying()[ix].pid()>0 && BP.modeMatches(ix,2,mode ) ) sign= 1.;
56 else if ( BP.decaying()[ix].pid()<0 && BP.modeMatches(ix,2,modeCC) ) sign=-1.;
57 else continue;
58 // find D* decay products
59 const Particle & Dstar = BP.decayProducts()[ix].at(-sign*423)[0];
60 if(Dstar.children().size()!=2) continue;
61 Particle D0;
62 unsigned int imode=0;
63 if(Dstar.children()[0].pid()== 111 &&
64 Dstar.children()[1].pid()==-sign*421) {
65 D0 = Dstar.children()[1];
66 imode=0;
67 }
68 else if(Dstar.children()[1].pid()== 111 &&
69 Dstar.children()[0].pid()==-sign*421) {
70 imode=0;
71 D0 = Dstar.children()[0];
72 }
73 else if(Dstar.children()[0].pid()== 22 &&
74 Dstar.children()[1].pid()==-sign*421) {
75 D0 = Dstar.children()[1];
76 imode=1;
77 }
78 else if(Dstar.children()[1].pid()== 22 &&
79 Dstar.children()[0].pid()==-sign*421) {
80 imode=1;
81 D0 = Dstar.children()[0];
82 }
83 else
84 continue;
85 // K* decay products
86 const Particle & Kstar = BP.decayProducts()[ix].at( sign*323)[0];
87 if(Kstar.children().size()!=2) continue;
88 Particle KK;
89 if(isK (Kstar.children()[0].abspid()) &&
90 isPi(Kstar.children()[1].abspid()))
91 KK = Kstar.children()[0];
92 else if(isK (Kstar.children()[1].abspid()) &&
93 isPi(Kstar.children()[0].abspid()))
94 KK = Kstar.children()[1];
95 else continue;
96 // boost to B rest frame
97 LorentzTransform boost =
98 LorentzTransform::mkFrameTransformFromBeta(BP.decaying()[ix]. momentum().betaVec());
99 FourMomentum pKstar = boost.transform(Kstar.momentum());
100 FourMomentum pDstar = boost.transform(Dstar.momentum());
101 FourMomentum pK = boost.transform(KK .momentum());
102 FourMomentum pD = boost.transform(D0 .momentum());
103 const LorentzTransform boost2 = LorentzTransform::mkFrameTransformFromBeta(pDstar.betaVec());
104 pD = boost2.transform(pD);
105 double cD = pD.p3().unit().dot(pDstar.p3().unit());
106 const LorentzTransform boost3 = LorentzTransform::mkFrameTransformFromBeta(pKstar.betaVec());
107 pK = boost3.transform(pK);
108 double cK = pK.p3().unit().dot(pKstar.p3().unit());
109 if(imode==0) {
110 _p[0]->fill(-0.5*(1-5*sqr(cK)));
111 _p[1]->fill();
112 }
113 _h[0][imode]->fill(cD);
114 _h[1][imode]->fill(cK);
115 }
116 }
117
118
119 /// Normalise histograms etc., after the run
120 void finalize() {
121 for(unsigned int ix=0;ix<2;++ix)
122 for(unsigned int iy=0;iy<2;++iy)
123 normalize(_h[ix][iy],1.,false);
124 Estimate0DPtr tmp;
125 book(tmp,1,1,1);
126 divide(*_p[0],*_p[1],tmp);
127 }
128
129 /// @}
130
131
132 /// @name Histograms
133 /// @{
134 Histo1DPtr _h[2][2];
135 CounterPtr _p[2];
136 /// @}
137
138
139 };
140
141
142 RIVET_DECLARE_PLUGIN(BABAR_2004_I626518);
143
144}
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