Rivet analyses referenceBABAR_2017_I1498564Electron spectrum inclusive semi-leptonic in B decaysExperiment: BABAR (PEP-II) Inspire ID: 1498564 Status: VALIDATED NOHEPDATA Authors:
Beam energies: ANY Run details:
Measurement of the electron spectrum inclusive semi-leptonic in $B$ decays, including both the total and the charmless. N.B. The spectum is obtained in the rest frame of the decaying $\Upsilon(4S)$ which produces the decaying $B$ mesons Source code: BABAR_2017_I1498564.cc 1// -*- C++ -*-
2#include "Rivet/Analysis.hh"
3#include "Rivet/Projections/UnstableParticles.hh"
4
5namespace Rivet {
6
7
8 /// @brief Electron spectrum in B decays
9 class BABAR_2017_I1498564 : public Analysis {
10 public:
11
12 /// Constructor
13 RIVET_DEFAULT_ANALYSIS_CTOR(BABAR_2017_I1498564);
14
15
16 /// @name Analysis methods
17 //@{
18
19 /// Book histograms and initialise projections before the run
20 void init() {
21 // projections
22 declare(UnstableParticles(Cuts::pid==300553),"UFS");
23 // Book histograms
24 // specify custom binning
25 book(_h_light, 1,1,1);
26 book(_h_all , 1,1,2);
27 book(_nB,"/TMP/nB");
28 }
29
30
31 void findDecayProducts(Particle parent, Particles & em, Particles & ep,
32 Particles & nue, Particles & nueBar, bool & charm) {
33 for(const Particle & p : parent.children()) {
34 if(PID::isCharmHadron(p.pid())) {
35 charm=true;
36 }
37 else if(p.pid() == PID::EMINUS) {
38 em.push_back(p);
39 }
40 else if(p.pid() == PID::EPLUS) {
41 ep.push_back(p);
42 }
43 else if(p.pid() == PID::NU_E) {
44 nue.push_back(p);
45 }
46 else if(p.pid() == PID::NU_EBAR) {
47 nueBar.push_back(p);
48 }
49 else if(PID::isBottomHadron(p.pid())) {
50 findDecayProducts(p,em,ep,nue,nueBar,charm);
51 }
52 else if(!PID::isHadron(p.pid())) {
53 findDecayProducts(p,em,ep,nue,nueBar,charm);
54 }
55 }
56 }
57
58
59 /// Perform the per-event analysis
60 void analyze(const Event& event) {
61 // find and loop over Upslion(4S)
62 for (const Particle& p : apply<UnstableParticles>(event, "UFS").particles()) {
63 // boost to rest frame
64 LorentzTransform cms_boost;
65 if (p.p3().mod() > 1*MeV)
66 cms_boost = LorentzTransform::mkFrameTransformFromBeta(p.momentum().betaVec());
67 // loop over decay products
68 for(const Particle & p2 : p.children()) {
69 if(p2.abspid()==511 || p2.abspid()==521) {
70 _nB->fill();
71 bool charm = false;
72 Particles em,ep,nue,nueBar;
73 findDecayProducts(p2,em,ep,nue,nueBar,charm);
74 if(em.size()==1 && nueBar.size()==1) {
75 double pmod = cms_boost.transform(em[0].momentum()).p3().mod();
76 _h_all->fill(pmod);
77 if(!charm) _h_light->fill(pmod);
78 }
79 else if(ep.size()==1 && nue.size()==1) {
80 double pmod = cms_boost.transform(ep[0].momentum()).p3().mod();
81 _h_all->fill(pmod);
82 if(!charm) _h_light->fill(pmod);
83 }
84 }
85 }
86 }
87 }
88
89
90 /// Normalise histograms etc., after the run
91 void finalize() {
92
93 // normalize to number of B decays
94 scale(_h_all, 1./ *_nB);
95 scale(_h_light, 1./ *_nB);
96 }
97
98 //@}
99
100
101 /// @name Histograms
102 //@{
103 Histo1DPtr _h_light,_h_all;
104 CounterPtr _nB;
105 //@}
106
107
108 };
109
110
111 RIVET_DECLARE_PLUGIN(BABAR_2017_I1498564);
112
113}
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