Rivet analyses referenceBELLE_2015_I1397632Exclusive semileptonic $B$ to $D$ decays.Experiment: BELLE (KEKB) Inspire ID: 1397632 Status: VALIDATED Authors:
Beams: * * Beam energies: ANY Run details:
Implementation of Lorentz invariant recoil w distributions for semileptonic B decays Source code: BELLE_2015_I1397632.cc 1// -*- C++ -*-
2#include "Rivet/Analysis.hh"
3#include "Rivet/Projections/UnstableParticles.hh"
4
5namespace Rivet {
6
7
8 /// @brief B -> D semi-leptonic
9 class BELLE_2015_I1397632 : public Analysis {
10 public:
11
12 /// Constructor
13 RIVET_DEFAULT_ANALYSIS_CTOR(BELLE_2015_I1397632);
14
15
16 /// @name Analysis methods
17 /// @{
18
19 /// Book histograms and initialise projections before the run
20 void init() {
21
22 // Initialise and register projections
23
24 declare(UnstableParticles(), "UFS");
25
26 // Book histograms
27 book(_h_B_Denu, 1, 1, 1);
28 book(_h_B_Dmunu, 1, 1, 2);
29 book(_h_B_Deplusnu, 2, 1, 1);
30 book(_h_B_Dmuplusnu, 2, 1, 2);
31 }
32
33 // Check for explicit decay into pdgids
34 bool isSemileptonicDecay(const Particle& mother, vector<int> ids) {
35 // Trivial check to ignore any other decays but the one in question modulo photons
36 const Particles children = mother.children(Cuts::pid!=PID::PHOTON);
37 if (children.size()!=ids.size()) return false;
38 // Check for the explicit decay
39 return all(ids, [&](int i){return count(children, hasPID(i))==1;});
40 }
41
42 // Calculate the recoil w using mother and daugher meson
43 double recoilW(const Particle& B, int mesonID) {
44 // TODO why does that not work with const?
45 Particle D = select(B.children(), Cuts::pid==mesonID)[0];
46 FourMomentum q = B.mom() - D.mom();
47 return (B.mom()*B.mom() + D.mom()*D.mom() - q*q )/ (2. * sqrt(B.mom()*B.mom()) * sqrt(D.mom()*D.mom()) );
48 }
49
50
51 /// Perform the per-event analysis
52 void analyze(const Event& event) {
53 // Get B0 Mesons
54 for(const Particle& p : apply<UnstableParticles>(event, "UFS").particles(Cuts::pid==PID::B0)) {
55 if (isSemileptonicDecay(p, {PID::DMINUS,PID::POSITRON,PID::NU_E})) _h_B_Denu->fill( recoilW(p, PID::DMINUS));
56 if (isSemileptonicDecay(p, {PID::DMINUS,PID::ANTIMUON,PID::NU_MU})) _h_B_Dmunu->fill(recoilW(p, PID::DMINUS));
57 }
58 // Get B+ Mesons
59 for(const Particle& p : apply<UnstableParticles>(event, "UFS").particles(Cuts::pid==PID::BPLUS)) {
60 if (isSemileptonicDecay(p, {PID::D0BAR,PID::POSITRON,PID::NU_E})) _h_B_Deplusnu->fill( recoilW(p, PID::D0BAR));
61 if (isSemileptonicDecay(p, {PID::D0BAR,PID::ANTIMUON,PID::NU_MU})) _h_B_Dmuplusnu->fill(recoilW(p, PID::D0BAR));
62 }
63 }
64
65
66 /// Normalise histograms etc., after the run
67 void finalize() {
68
69 normalize(_h_B_Denu);
70 normalize(_h_B_Dmunu);
71 normalize(_h_B_Deplusnu);
72 normalize(_h_B_Dmuplusnu);
73
74 }
75
76 /// @}
77
78
79 private:
80
81
82 /// @name Histograms
83 /// @{
84 Histo1DPtr _h_B_Denu;
85 Histo1DPtr _h_B_Dmunu;
86 Histo1DPtr _h_B_Deplusnu;
87 Histo1DPtr _h_B_Dmuplusnu;
88 /// @}
89
90
91 };
92
93
94 RIVET_DECLARE_PLUGIN(BELLE_2015_I1397632);
95
96
97}
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