Rivet analyses referenceBABAR_2010_I879997Kinematic distributions in $D^+\to K^-\pi^+ e^+\nu_e$Experiment: BABAR (PEP-II) Inspire ID: 879997 Status: VALIDATED NOHEPDATA Authors:
Beam energies: ANY Run details:
Measurement of the kinematic distributions in $D^+\to K^-\pi^+ e^+\nu_e$ by BABAR. The data were read from the paper and may not have been corrected for acceptance. In many cases the error bar is the size of the point Source code: BABAR_2010_I879997.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 D+ -> K- pi+ e+ nu_e
10 class BABAR_2010_I879997 : public Analysis {
11 public:
12
13 /// Constructor
14 RIVET_DEFAULT_ANALYSIS_CTOR(BABAR_2010_I879997);
15
16
17 /// @name Analysis methods
18 /// @{
19
20 /// Book histograms and initialise projections before the run
21 void init() {
22
23 // Initialise and register projections
24 UnstableParticles ufs = UnstableParticles(Cuts::pid==411);
25 declare(ufs, "UFS");
26 DecayedParticles DP(ufs);
27 DP.addStable(PID::PI0);
28 DP.addStable(PID::K0S);
29 DP.addStable(PID::ETA);
30 DP.addStable(PID::ETAPRIME);
31 declare(DP, "DP");
32
33 // Book histograms
34 for (size_t ix=0; ix<5; ++ix) {
35 book(_h[ix],1,1,1+ix);
36 }
37 const vector<double> bins{0.,0.8,0.9,1.,1.6};
38 for (size_t ix=0; ix<4; ++ix) {
39 book(_b[ix], bins);
40 for (auto& b : _b[ix]->bins()) {
41 book(b, 1+b.index(), 1, 1+ix);
42 }
43 }
44 }
45
46
47 /// Perform the per-event analysis
48 void analyze(const Event& event) {
49 static const map<PdgId,unsigned int> & mode = { { -321,1}, { 211,1}, {-11,1}, { 12,1}};
50 DecayedParticles DP = apply<DecayedParticles>(event, "DP");
51 // loop over particles
52 for (unsigned int ix=0;ix<DP.decaying().size();++ix) {
53 if ( !DP.modeMatches(ix,4,mode) ) continue;
54 const Particle & Km = DP.decayProducts()[ix].at(-321)[0];
55 const Particle & pip= DP.decayProducts()[ix].at( 211)[0];
56 const Particle & ep = DP.decayProducts()[ix].at( -11)[0];
57 const Particle & nue= DP.decayProducts()[ix].at( 12)[0];
58 FourMomentum pKstar = Km.momentum()+pip.momentum();
59 double mKpi = pKstar.mass();
60 _h[4]->fill(mKpi);
61 FourMomentum qq = DP.decaying()[ix].momentum()-pKstar;
62 double q2 = qq.mass2();
63 _h[0]->fill(q2);
64 _b[0]->fill(mKpi,q2);
65 // boost momenta to DP rest frame
66 LorentzTransform boost = LorentzTransform::mkFrameTransformFromBeta(DP.decaying()[ix].momentum().betaVec());
67 FourMomentum pKS = boost.transform(pKstar);
68 Matrix3 ptoz(-pKS.p3().unit(), Vector3(0,0,1));
69 boost.preMult(ptoz);
70 // the momenta in frane to W along z
71 FourMomentum pD = boost.transform(DP.decaying()[ix].momentum());
72 FourMomentum pK = boost.transform(Km .momentum());
73 FourMomentum ppi = boost.transform(pip.momentum());
74 FourMomentum pe = boost.transform(ep .momentum());
75 FourMomentum pnu = boost.transform(nue.momentum());
76 pKstar = pK+ppi;
77 qq = pD-pKstar;
78 LorentzTransform boostK = LorentzTransform::mkFrameTransformFromBeta(pKstar.betaVec());
79 Vector3 axisK = boostK.transform(pK).p3().unit();
80 double cosK = axisK.dot(pKstar.p3().unit());
81 _h[2]->fill(cosK);
82 _b[2]->fill(mKpi,cosK);
83 LorentzTransform boostW = LorentzTransform::mkFrameTransformFromBeta(qq.betaVec());
84 Vector3 axisE = boostW.transform(pe).p3().unit();
85 double cosE = axisE.dot(qq.p3().unit());
86 _h[3]->fill(cosE);
87 _b[3]->fill(mKpi,cosE);
88 axisK.setZ(0.);
89 axisE.setZ(0.);
90 double chi = atan2(axisE.cross(axisK).dot(qq.p3().unit()), axisE.dot(axisK));
91 _h[1]->fill(chi);
92 _b[1]->fill(mKpi, chi);
93 }
94 }
95
96
97 /// Normalise histograms etc., after the run
98 void finalize() {
99 normalize(_h);
100 normalize(_b);
101 }
102
103 /// @}
104
105
106 /// @name Histograms
107 /// @{
108 Histo1DPtr _h[5];
109 Histo1DGroupPtr _b[4];
110 /// @}
111
112
113 };
114
115
116 RIVET_DECLARE_PLUGIN(BABAR_2010_I879997);
117
118}
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