Rivet analyses referenceBABAR_2007_I1091435$D^0\to K^- e^+\nu_e$ $q^2$ spectrumExperiment: BABAR (PEP-II) Inspire ID: 1091435 Status: VALIDATED Authors:
Beam energies: ANY Run details:
Measurement of the $q^2$ spectrum in the decay $D^0\to K^- e^+\nu_e$ by BaBar. Source code: BABAR_2007_I1091435.cc 1// -*- C++ -*-
2#include "Rivet/Analysis.hh"
3#include "Rivet/Projections/UnstableParticles.hh"
4
5namespace Rivet {
6
7
8 /// @brief q^2 in D0 -> K- e+ nu_e decays
9 class BABAR_2007_I1091435 : public Analysis {
10 public:
11
12 /// Constructor
13 RIVET_DEFAULT_ANALYSIS_CTOR(BABAR_2007_I1091435);
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 declare(UnstableParticles(), "UFS");
24
25 // Book histograms
26 book(_h_q2 ,1, 1, 1);
27 }
28
29 // Calculate the Q2 using mother and daugher meson
30 double q2(const Particle& B, int mesonID) {
31 FourMomentum q = B.mom() - select(B.children(), Cuts::pid==mesonID)[0];
32 return q*q;
33 }
34
35 // Check for explicit decay into pdgids
36 bool isSemileptonicDecay(const Particle& mother, vector<int> ids) {
37 // Trivial check to ignore any other decays but the one in question modulo photons
38 const Particles children = mother.children(Cuts::pid!=PID::PHOTON);
39 if (children.size()!=ids.size()) return false;
40 // Check for the explicit decay
41 return all(ids, [&](int i){return count(children, hasPID(i))==1;});
42 }
43
44 /// Perform the per-event analysis
45 void analyze(const Event& event) {
46 // Loop over B0 mesons
47 for(const Particle& p : apply<UnstableParticles>(event, "UFS").particles(Cuts::pid==PID::D0)) {
48 if (isSemileptonicDecay(p, {PID::KMINUS, PID::POSITRON, PID::NU_E}) ) {
49 _h_q2->fill(q2(p, PID::KMINUS));
50 }
51 }
52 }
53
54
55 /// Normalise histograms etc., after the run
56 void finalize() {
57 normalize(_h_q2, 1.);
58 }
59
60 /// @}
61
62
63 /// @name Histograms
64 /// @{
65 Histo1DPtr _h_q2;
66 /// @}
67
68
69 };
70
71
72 RIVET_DECLARE_PLUGIN(BABAR_2007_I1091435);
73
74}
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