Rivet analyses referenceBESIII_2016_I1411645Kinematic distributions in $D^+\to K^-\pi^+ e^+\nu_e$Experiment: BESIII (BEPC) Inspire ID: 1411645 Status: VALIDATED Authors:
Beam energies: ANY Run details:
Measurement of the kinematic distributions in $D^+\to K^-\pi^+ e^+\nu_e$ by BES-III. N.B. Although there is some data in HEPDATA it is not physical and therefore the data were read from the paper and may not have been corrected for acceptance. Source code: BESIII_2016_I1411645.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 BESIII_2016_I1411645 : public Analysis {
11 public:
12
13 /// Constructor
14 RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2016_I1411645);
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(unsigned int ix=0;ix<6;++ix)
35 book(_h[ix],3,1,1+ix);
36 }
37
38
39 /// Perform the per-event analysis
40 void analyze(const Event& event) {
41 static const map<PdgId,unsigned int> & mode = { { -321,1}, { 211,1}, {-11,1}, { 12,1}};
42 DecayedParticles DP = apply<DecayedParticles>(event, "DP");
43 // loop over particles
44 for(unsigned int ix=0;ix<DP.decaying().size();++ix) {
45 if ( !DP.modeMatches(ix,4,mode) ) continue;
46 const Particle & Km = DP.decayProducts()[ix].at(-321)[0];
47 const Particle & pip= DP.decayProducts()[ix].at( 211)[0];
48 const Particle & ep = DP.decayProducts()[ix].at( -11)[0];
49 const Particle & nue= DP.decayProducts()[ix].at( 12)[0];
50 FourMomentum pKstar = Km.momentum()+pip.momentum();
51 _h[0]->fill(pKstar.mass());
52 _h[1]->fill(pKstar.mass());
53 FourMomentum qq = DP.decaying()[ix].momentum()-pKstar;
54 _h[2]->fill(qq.mass2());
55 // boost momenta to DP rest frame
56 LorentzTransform boost = LorentzTransform::mkFrameTransformFromBeta(DP.decaying()[ix].momentum().betaVec());
57 FourMomentum pKS = boost.transform(pKstar);
58 Matrix3 ptoz(-pKS.p3().unit(), Vector3(0,0,1));
59 boost.preMult(ptoz);
60 // the momenta in frane to W along z
61 FourMomentum pD = boost.transform(DP.decaying()[ix].momentum());
62 FourMomentum pK = boost.transform(Km .momentum());
63 FourMomentum ppi = boost.transform(pip.momentum());
64 FourMomentum pe = boost.transform(ep .momentum());
65 FourMomentum pnu = boost.transform(nue.momentum());
66 pKstar = pK+ppi;
67 qq = pD-pKstar;
68 LorentzTransform boostK = LorentzTransform::mkFrameTransformFromBeta(pKstar.betaVec());
69 Vector3 axisK = boostK.transform(pK).p3().unit();
70 _h[4]->fill(axisK.dot(pKstar.p3().unit()));
71 LorentzTransform boostW = LorentzTransform::mkFrameTransformFromBeta( qq.betaVec());
72 Vector3 axisE = boostW.transform(pe).p3().unit();
73 _h[3]->fill(axisE.dot(qq.p3().unit()));
74 axisK.setZ(0.);
75 axisE.setZ(0.);
76 double chi = atan2(axisE.cross(axisK).dot(qq.p3().unit()), axisE.dot(axisK));
77 _h[5]->fill(chi);
78 }
79 }
80
81
82 /// Normalise histograms etc., after the run
83 void finalize() {
84 for(unsigned int ix=0;ix<6;++ix)
85 normalize(_h[ix]);
86 }
87
88 /// @}
89
90
91 /// @name Histograms
92 /// @{
93 Histo1DPtr _h[6];
94 /// @}
95
96
97 };
98
99
100 RIVET_DECLARE_PLUGIN(BESIII_2016_I1411645);
101
102}
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