Rivet analyses referenceBESIII_2018_I1705754Kinematic distributions in $D^0\to \bar{K}^0\pi^- e^+\nu_e$Experiment: BESIII (BEPC) Inspire ID: 1705754 Status: VALIDATED NOHEPDATA Authors:
Beam energies: ANY Run details:
Measurement of the kinematic distributions in $D^0\to \bar{K}^0\pi^- e^+\nu_e$ by BES-III. N.B. the plots where read from the paper and may not have been corrected for acceptance. Source code: BESIII_2018_I1705754.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 D0 -> Kbar0 pi- e+ nu_e
10 class BESIII_2018_I1705754 : public Analysis {
11 public:
12
13 /// Constructor
14 RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2018_I1705754);
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==421);
25 declare(ufs, "UFS");
26 DecayedParticles D0(ufs);
27 D0.addStable(PID::PI0);
28 D0.addStable(PID::K0S);
29 D0.addStable(PID::ETA);
30 D0.addStable(PID::ETAPRIME);
31 declare(D0, "D0");
32
33 // Book histograms
34 for(unsigned int ix=0;ix<5;++ix)
35 book(_h[ix],1,1,1+ix);
36 }
37
38
39 /// Perform the per-event analysis
40 void analyze(const Event& event) {
41 static const map<PdgId,unsigned int> & mode1 = { { 310,1}, {-211,1}, {-11,1}, { 12,1}};
42 static const map<PdgId,unsigned int> & mode2 = { { 130,1}, {-211,1}, {-11,1}, { 12,1}};
43 static const map<PdgId,unsigned int> & mode3 = { {-311,1}, {-211,1}, {-11,1}, { 12,1}};
44 DecayedParticles D0 = apply<DecayedParticles>(event, "D0");
45 // loop over particles
46 for(unsigned int ix=0;ix<D0.decaying().size();++ix) {
47 Particle K0;
48 if (D0.modeMatches(ix,4,mode1)) K0=D0.decayProducts()[ix].at( 310)[0];
49 else if(D0.modeMatches(ix,4,mode2)) K0=D0.decayProducts()[ix].at( 130)[0];
50 else if(D0.modeMatches(ix,4,mode3)) K0=D0.decayProducts()[ix].at(-311)[0];
51 else continue;
52 const Particle & pim= D0.decayProducts()[ix].at(-211)[0];
53 const Particle & ep = D0.decayProducts()[ix].at(-11)[0];
54 const Particle & nue= D0.decayProducts()[ix].at( 12)[0];
55 FourMomentum pKstar = K0.momentum()+pim.momentum();
56 _h[0]->fill(pKstar.mass());
57 FourMomentum qq = D0.decaying()[ix].momentum()-pKstar;
58 _h[1]->fill(qq.mass2());
59 // boost momenta to D0 rest frame
60 LorentzTransform boost = LorentzTransform::mkFrameTransformFromBeta(D0.decaying()[ix].momentum().betaVec());
61 FourMomentum pKS = boost.transform(pKstar);
62 Matrix3 ptoz(-pKS.p3().unit(), Vector3(0,0,1));
63 boost.preMult(ptoz);
64 // the momenta in frane to W along z
65 FourMomentum pD = boost.transform(D0.decaying()[ix].momentum());
66 FourMomentum pK = boost.transform(K0 .momentum());
67 FourMomentum ppi = boost.transform(pim.momentum());
68 FourMomentum pe = boost.transform(ep .momentum());
69 FourMomentum pnu = boost.transform(nue.momentum());
70 pKstar = pK+ppi;
71 qq = pD-pKstar;
72 LorentzTransform boostK = LorentzTransform::mkFrameTransformFromBeta(pKstar.betaVec());
73 Vector3 axisK = boostK.transform(pK).p3().unit();
74 _h[3]->fill(axisK.dot(pKstar.p3().unit()));
75 LorentzTransform boostW = LorentzTransform::mkFrameTransformFromBeta( qq.betaVec());
76 Vector3 axisE = boostW.transform(pe).p3().unit();
77 _h[2]->fill(axisE.dot(qq.p3().unit()));
78 axisK.setZ(0.);
79 axisE.setZ(0.);
80 double chi = atan2(axisE.cross(axisK).dot(qq.p3().unit()), axisE.dot(axisK));
81 _h[4]->fill(chi);
82 }
83 }
84
85
86 /// Normalise histograms etc., after the run
87 void finalize() {
88 for(unsigned int ix=0;ix<5;++ix)
89 normalize(_h[ix]);
90 }
91
92 /// @}
93
94
95 /// @name Histograms
96 /// @{
97 Histo1DPtr _h[5];
98 /// @}
99
100
101 };
102
103
104 RIVET_DECLARE_PLUGIN(BESIII_2018_I1705754);
105
106}
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