Rivet analyses referenceBESIII_2019_I1702549$D_s^+\to K^0 e^+\nu_e$ $q^2$ spectrum $D_s^+\to K^{*0} e^+\nu_e$ $q^2$ distributionsExperiment: BESIII (BEPC) Inspire ID: 1702549 Status: VALIDATED Authors:
Beam energies: ANY Run details:
Measurement of the $q^2$ spectrum in the decay $D_s^+\to K^0 e^+\nu_e$ and kinematic distributions in $D_s^+\to K^{*0} e^+\nu_e$ $q^2$ by BES-III. N.B. the plots where read from the paper and may not have been corrected for acceptance. Source code: BESIII_2019_I1702549.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 q^2 in D_s+ -> K0 e+ nu_e and ->K*0 e+ nu_e distributions
10 class BESIII_2019_I1702549 : public Analysis {
11 public:
12
13 /// Constructor
14 RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2019_I1702549);
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==431);
25 declare(ufs, "UFS");
26 DecayedParticles DS(ufs);
27 DS.addStable(PID::PI0);
28 DS.addStable(PID::K0S);
29 DS.addStable(PID::ETA);
30 DS.addStable(PID::ETAPRIME);
31 declare(DS, "DS");
32
33 // Book histograms
34 book(_h_q2, 1, 1, 1);
35 book(_nD,"/TMP/nD");
36 for(unsigned int ix=0;ix<5;++ix)
37 book(_h_Kstar[ix],1,1,3+ix);
38 }
39
40 /// Perform the per-event analysis
41 void analyze(const Event& event) {
42 static const map<PdgId,unsigned int> & mode1 = { { 310,1}, {-11,1}, { 12,1}};
43 static const map<PdgId,unsigned int> & mode2 = { { 130,1}, {-11,1}, { 12,1}};
44 static const map<PdgId,unsigned int> & mode3 = { { 311,1}, {-11,1}, { 12,1}};
45 static const map<PdgId,unsigned int> & mode4 = { { 321,1}, {-211,1}, {-11,1}, { 12,1}};
46 DecayedParticles DS = apply<DecayedParticles>(event, "DS");
47 // loop over particles
48 for(unsigned int ix=0;ix<DS.decaying().size();++ix) {
49 _nD->fill();
50 if(DS.modeMatches(ix,3,mode1)) {
51 _h_q2->fill((DS.decaying()[ix].momentum()-DS.decayProducts()[ix].at(310)[0].momentum()).mass2());
52 }
53 else if(DS.modeMatches(ix,3,mode2)) {
54 _h_q2->fill((DS.decaying()[ix].momentum()-DS.decayProducts()[ix].at(130)[0].momentum()).mass2());
55 }
56 else if(DS.modeMatches(ix,3,mode3)) {
57 _h_q2->fill((DS.decaying()[ix].momentum()-DS.decayProducts()[ix].at(311)[0].momentum()).mass2());
58 }
59 else if(DS.modeMatches(ix,4,mode4)) {
60 const Particle & Kp = DS.decayProducts()[ix].at( 321)[0];
61 const Particle & pim= DS.decayProducts()[ix].at(-211)[0];
62 const Particle & ep = DS.decayProducts()[ix].at(-11)[0];
63 const Particle & nue= DS.decayProducts()[ix].at( 12)[0];
64 FourMomentum pKstar = Kp.momentum()+pim.momentum();
65 _h_Kstar[0]->fill(pKstar.mass());
66 FourMomentum qq = DS.decaying()[ix].momentum()-pKstar;
67 _h_Kstar[1]->fill(qq.mass2());
68 // boost momenta to Ds rest frame
69 LorentzTransform boost = LorentzTransform::mkFrameTransformFromBeta(DS.decaying()[ix].momentum().betaVec());
70 FourMomentum pKS = boost.transform(pKstar);
71 Matrix3 ptoz(-pKS.p3().unit(), Vector3(0,0,1));
72 boost.preMult(ptoz);
73 // the momenta in frane to W along z
74 FourMomentum pD = boost.transform(DS.decaying()[ix].momentum());
75 FourMomentum pK = boost.transform(Kp .momentum());
76 FourMomentum ppi = boost.transform(pim.momentum());
77 FourMomentum pe = boost.transform(ep .momentum());
78 FourMomentum pnu = boost.transform(nue.momentum());
79 pKstar = pK+ppi;
80 qq = pD-pKstar;
81 LorentzTransform boostK = LorentzTransform::mkFrameTransformFromBeta(pKstar.betaVec());
82 Vector3 axisK = boostK.transform(pK).p3().unit();
83 _h_Kstar[3]->fill(axisK.dot(pKstar.p3().unit()));
84 LorentzTransform boostW = LorentzTransform::mkFrameTransformFromBeta( qq.betaVec());
85 Vector3 axisE = boostW.transform(pe).p3().unit();
86 _h_Kstar[2]->fill(axisE.dot(qq.p3().unit()));
87 axisK.setZ(0.);
88 axisE.setZ(0.);
89 double chi = atan2(axisE.cross(axisK).dot(qq.p3().unit()), axisE.dot(axisK));
90 _h_Kstar[4]->fill(chi);
91 }
92 }
93 }
94
95
96 /// Normalise histograms etc., after the run
97 void finalize() {
98 // normalise to width in inverse ns
99 scale(_h_q2, 1./0.504e-3/ *_nD);
100 for (unsigned int ix=0;ix<5;++ix) {
101 normalize(_h_Kstar[ix]);
102 }
103 }
104
105 /// @}
106
107
108 /// @name Histograms
109 /// @{
110 Histo1DPtr _h_q2;
111 Histo1DPtr _h_Kstar[5];
112 CounterPtr _nD;
113 /// @}
114
115
116 };
117
118
119 RIVET_DECLARE_PLUGIN(BESIII_2019_I1702549);
120
121}
|
