Rivet analyses referenceBESIII_2019_I1694530Kinematic distributions in $D^0\to \pi^-\pi^0 e^+\nu_e$ and $D^+\to \pi^+\pi^- e^+\nu_e$Experiment: BESIII (BEPC) Inspire ID: 1694530 Status: VALIDATED NOHEPDATA Authors:
Beam energies: ANY Run details:
Measurement of the kinematic distributions in $D^0\to \pi^-\pi^0 e^+\nu_e$ and $D^+\to \pi^+\pi^- e^+\nu_e$ by BES-III. N.B. the plots where read from the paper and may not have been corrected for acceptance. Source code: BESIII_2019_I1694530.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 -> pi pi semileptonic
10 class BESIII_2019_I1694530 : public Analysis {
11 public:
12
13 /// Constructor
14 RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2019_I1694530);
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 ||Cuts::pid==421);
25 declare(ufs, "UFS");
26 DecayedParticles DD(ufs);
27 DD.addStable(PID::PI0);
28 DD.addStable(PID::K0S);
29 DD.addStable(PID::ETA);
30 DD.addStable(PID::ETAPRIME);
31 declare(DD, "DD");
32
33 // Book histograms
34 for(unsigned int ix=0;ix<10;++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 = { { 111,1}, {-211,1}, {-11,1}, { 12,1}};
42 static const map<PdgId,unsigned int> & mode2 = { { 211,1}, {-211,1}, {-11,1}, { 12,1}};
43 DecayedParticles DD = apply<DecayedParticles>(event, "DD");
44 // loop over particles
45 for(unsigned int ix=0;ix<DD.decaying().size();++ix) {
46 Particle pi2;
47 int imode=-1;
48 if (DD.decaying()[ix].pid()==421 && DD.modeMatches(ix,4,mode1)) {
49 pi2= DD.decayProducts()[ix].at(111)[0];
50 imode=0;
51 }
52 else if(DD.decaying()[ix].pid()==411 && DD.modeMatches(ix,4,mode2)) {
53 pi2= DD.decayProducts()[ix].at(211)[0];
54 imode=5;
55 }
56 else continue;
57 const Particle & pim= DD.decayProducts()[ix].at(-211)[0];
58 if (imode==5 && abs((pi2.momentum()+pim.momentum()).mass()-.497611)<0.07) continue;
59 const Particle & ep = DD.decayProducts()[ix].at(-11)[0];
60 const Particle & nue= DD.decayProducts()[ix].at( 12)[0];
61 FourMomentum pRho = pi2.momentum()+pim.momentum();
62 _h[imode]->fill(pRho.mass());
63 FourMomentum qq = DD.decaying()[ix].momentum()-pRho;
64 _h[imode+1]->fill(qq.mass2());
65 // boost momenta to D rest frame
66 LorentzTransform boost = LorentzTransform::mkFrameTransformFromBeta(DD.decaying()[ix].momentum().betaVec());
67 FourMomentum pPP = boost.transform(pRho);
68 Matrix3 ptoz(-pPP.p3().unit(), Vector3(0,0,1));
69 boost.preMult(ptoz);
70 // the momenta in frane to W along z
71 FourMomentum pD = boost.transform(DD.decaying()[ix].momentum());
72 FourMomentum ppi2 = boost.transform(pi2.momentum());
73 FourMomentum ppim = boost.transform(pim.momentum());
74 FourMomentum pe = boost.transform(ep .momentum());
75 FourMomentum pnu = boost.transform(nue.momentum());
76 pRho = ppi2+ppim;
77 qq = pD-pRho;
78 LorentzTransform boostRho = LorentzTransform::mkFrameTransformFromBeta(pRho.betaVec());
79 Vector3 axisRho = boostRho.transform(ppim).p3().unit();
80 _h[imode+2]->fill(axisRho.dot(pRho.p3().unit()));
81 LorentzTransform boostW = LorentzTransform::mkFrameTransformFromBeta( qq.betaVec());
82 Vector3 axisE = boostW.transform(pe).p3().unit();
83 _h[imode+3]->fill(axisE.dot(qq.p3().unit()));
84 axisRho.setZ(0.);
85 axisE.setZ(0.);
86 double chi = atan2(axisE.cross(axisRho).dot(qq.p3().unit()), axisE.dot(axisRho));
87 _h[imode+4]->fill(chi);
88 }
89 }
90
91
92 /// Normalise histograms etc., after the run
93 void finalize() {
94 for(unsigned int ix=0;ix<10;++ix)
95 normalize(_h[ix]);
96 }
97
98 /// @}
99
100
101 /// @name Histograms
102 /// @{
103 Histo1DPtr _h[10];
104 /// @}
105
106
107 };
108
109
110 RIVET_DECLARE_PLUGIN(BESIII_2019_I1694530);
111
112}
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