Rivet analyses referenceBELLE_2008_I768236$B\to D^*\ell\nu_\ell$ decaysExperiment: BELLE (KEKB) Inspire ID: 768236 Status: VALIDATED NOHEPDATA Authors:
Beam energies: ANY Run details:
Measurement of the hadronic mass, helicity and $w$ distributions for $B\to D^*\ell\nu_\ell$ decays. The background subtracted data was read from the plots in the paper. Source code: BELLE_2008_I768236.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** l nu
10 class BELLE_2008_I768236 : public Analysis {
11 public:
12
13 /// Constructor
14 RIVET_DEFAULT_ANALYSIS_CTOR(BELLE_2008_I768236);
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==511 || Cuts::abspid==521);
24 declare(ufs, "UFS");
25 DecayedParticles BB(ufs);
26 BB.addStable(411); BB.addStable(-411);
27 BB.addStable(421); BB.addStable(-421);
28 BB.addStable(413); BB.addStable(-413);
29 BB.addStable(423); BB.addStable(-423);
30 BB.addStable(PID::PI0);
31 declare(BB, "BB");
32 // hists
33 for (unsigned int ix=0; ix<4; ++ix) {
34 book(_h_mass[ix], 1, 1, 1+ix);
35 if (ix==3 || ix==1) continue;
36 book(_h_hel [ix], 2, 1, 1+ix);
37 book(_h_w [ix], 3, 1, 1+ix);
38 }
39 }
40
41
42 /// Perform the per-event analysis
43 void analyze(const Event& event) {
44 static const map<PdgId,unsigned int> mode1[4] = {{ {-411,1}, { 211,1}, {-11,1}, { 12,1}},
45 { { 411,1}, {-211,1}, { 11,1}, {-12,1}},
46 { {-411,1}, { 211,1}, {-13,1}, { 14,1}},
47 { { 411,1}, {-211,1}, { 13,1}, {-14,1}}};
48 static const map<PdgId,unsigned int> mode2[4] = {{ {-413,1}, { 211,1}, {-11,1}, { 12,1}},
49 { { 413,1}, {-211,1}, { 11,1}, {-12,1}},
50 { {-413,1}, { 211,1}, {-13,1}, { 14,1}},
51 { { 413,1}, {-211,1}, { 13,1}, {-14,1}}};
52 static const map<PdgId,unsigned int> mode3[4] = {{ {-421,1}, {-211,1}, {-11,1}, { 12,1}},
53 { { 421,1}, { 211,1}, { 11,1}, {-12,1}},
54 { {-421,1}, {-211,1}, {-13,1}, { 14,1}},
55 { { 421,1}, { 211,1}, { 13,1}, {-14,1}}};
56 static const map<PdgId,unsigned int> mode4[4] = {{ {-423,1}, {-211,1}, {-11,1}, { 12,1}},
57 { { 423,1}, { 211,1}, { 11,1}, {-12,1}},
58 { {-423,1}, {-211,1}, {-13,1}, { 14,1}},
59 { { 423,1}, { 211,1}, { 13,1}, {-14,1}}};
60 // loop over B mesons
61 DecayedParticles BB = apply<DecayedParticles>(event, "BB");
62 // loop over particles
63 for (unsigned int ix=0; ix<BB.decaying().size(); ++ix) {
64 for (unsigned int il=0; il<4; ++il) {
65 int iD,imode=0;
66 if ( BB.modeMatches(ix,4,mode1[il]) ) {
67 imode=0;
68 iD=411;
69 }
70 else if ( BB.modeMatches(ix,4,mode2[il]) ) {
71 imode=1;
72 iD=413;
73 }
74 else if ( BB.modeMatches(ix,4,mode3[il]) ) {
75 imode=2;
76 iD=421;
77 }
78 else if ( BB.modeMatches(ix,4,mode4[il]) ) {
79 imode=3;
80 iD=423;
81 }
82 else continue;
83 int sign = il%2==0 ? 1 : -1;
84 int ipi = -sign*211;
85 iD *= -sign;
86 if(imode<2) ipi*=-1;
87 const Particle & pi1= BB.decayProducts()[ix].at( ipi)[0];
88 const Particle & DD = BB.decayProducts()[ix].at( iD )[0];
89 FourMomentum pHad = pi1.mom()+DD.mom();
90 double mass = pHad.mass();
91 _h_mass[imode]->fill(mass);
92 // just the D pi modes for helicty and w
93 if (imode%2!=0) continue;
94 // check ingtermediate
95 int inter=-1;
96 for (unsigned int iz=0;iz<BB.decaying()[ix].children().size();++iz) {
97 if (BB.decaying()[ix].children()[iz].abspid()==10411 ||
98 BB.decaying()[ix].children()[iz].abspid()==10421) {
99 inter=0;
100 break;
101 }
102 else if (BB.decaying()[ix].children()[iz].abspid()==415 ||
103 BB.decaying()[ix].children()[iz].abspid()==425) {
104 inter=2;
105 break;
106 }
107 }
108 if (inter<0) continue;
109 // First boost all relevant momenta into the B-rest frame
110 const LorentzTransform boost1 = LorentzTransform::mkFrameTransformFromBeta(BB.decaying()[ix].mom().betaVec());
111 // Momenta in B rest frame:
112 FourMomentum pDSS = boost1.transform(pHad);
113 FourMomentum pW = boost1.transform(BB.decaying()[ix].mom() - pHad);
114 FourMomentum ppi = boost1.transform(pi1);
115 const LorentzTransform boost2 = LorentzTransform::mkFrameTransformFromBeta(pDSS.betaVec());
116 double ctheta = pW.p3().unit().dot(boost2.transform(ppi).p3().unit());
117 _h_hel[inter]->fill(abs(ctheta));
118 double mB2 = BB.decaying()[ix].mom().mass2();
119 double mD2 = sqr(mass);
120 double w = (mB2 + mD2 - pW.mass2())/ (2. * sqrt(mB2) * sqrt(mD2) );
121 _h_w[inter]->fill(w);
122 }
123 }
124 }
125
126
127 /// Normalise histograms etc., after the run
128 void finalize() {
129 normalize(_h_mass, 1.0, false);
130 normalize(_h_hel, 1.0, false);
131 normalize(_h_w, 1.0, false);
132 }
133
134 /// @}
135
136
137 /// @name Histograms
138 /// @{
139 Histo1DPtr _h_mass[4],_h_hel[3],_h_w[3];
140 /// @}
141
142
143 };
144
145
146 RIVET_DECLARE_PLUGIN(BELLE_2008_I768236);
147
148}
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