Rivet analyses referenceBABAR_2006_I722213Mass distributions in $\Lambda_c^+\to \Lambda\bar{K}^0K^+$Experiment: BABAR (PEP-II) Inspire ID: 722213 Status: VALIDATED NOHEPDATA Authors:
Beam energies: ANY Run details:
Measurement of the mass distributions in the decay $\Lambda_c^+\to \Lambda\bar{K}^0K^+$, together with angular distributions in the $\Xi(1690)$ region. The data were read from the plots in the paper but have been corrected for efficiency/acceptance but not resolution. Source code: BABAR_2006_I722213.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 Lambda_c+ -> Lambda Kbar0 K+
10 class BABAR_2006_I722213 : public Analysis {
11 public:
12
13 /// Constructor
14 RIVET_DEFAULT_ANALYSIS_CTOR(BABAR_2006_I722213);
15
16
17 /// @name Analysis methods
18 /// @{
19
20 /// Book histograms and initialise projections before the run
21 void init() {
22 // Initialise and register projections
23 UnstableParticles ufs = UnstableParticles(Cuts::abspid==4122);
24 declare(ufs, "UFS");
25 DecayedParticles LAMBDAC(ufs);
26 LAMBDAC.addStable(PID::PI0);
27 LAMBDAC.addStable(PID::K0S);
28 LAMBDAC.addStable(PID::ETA);
29 LAMBDAC.addStable(PID::LAMBDA);
30 LAMBDAC.addStable(-PID::LAMBDA);
31 declare(LAMBDAC, "LAMBDAC");
32 // histograms
33 for(unsigned int ix=0;ix<3;++ix)
34 book(_h_mass[ix],1,1,1+ix);
35 for(unsigned int ix=0;ix<2;++ix)
36 book(_h_ctheta[ix],2,1,1+ix);
37 }
38
39
40 /// Perform the per-event analysis
41 void analyze(const Event& event) {
42 static const map<PdgId,unsigned int> & mode = { { PID::LAMBDA,1}, { 321,1}, { 310,1}};
43 static const map<PdgId,unsigned int> & modeCC = { {-PID::LAMBDA,1}, {-321,1}, { 310,1}};
44 DecayedParticles LAMBDAC = apply<DecayedParticles>(event, "LAMBDAC");
45 // loop over particles
46 for(unsigned int ix=0;ix<LAMBDAC.decaying().size();++ix) {
47 int sign = 1;
48 if (LAMBDAC.decaying()[ix].pid()>0 && LAMBDAC.modeMatches(ix,3,mode)) {
49 sign=1;
50 }
51 else if (LAMBDAC.decaying()[ix].pid()<0 && LAMBDAC.modeMatches(ix,3,modeCC)) {
52 sign=-1;
53 }
54 else
55 continue;
56 const Particle & lam = LAMBDAC.decayProducts()[ix].at( sign*PID::LAMBDA)[0];
57 const Particle & K0 = LAMBDAC.decayProducts()[ix].at( 310)[0];
58 const Particle & Kp = LAMBDAC.decayProducts()[ix].at( sign*321)[0];
59 double mLamK = (lam.momentum()+K0.momentum()).mass();
60 _h_mass[0]->fill(mLamK);
61 _h_mass[1]->fill((Kp .momentum()+K0.momentum()).mass()-Kp.mass()-K0.mass());
62 _h_mass[2]->fill((lam.momentum()+Kp.momentum()).mass()-Kp.mass()-lam.mass());
63 // take Xi(1690) to be any resonance in mass region
64 if(mLamK<1.6725 || mLamK>1.6975) continue;
65 if(LAMBDAC.decaying()[ix].children().size()!=2) continue;
66 if(LAMBDAC.decaying()[ix].children()[0].abspid()!=321 &&
67 LAMBDAC.decaying()[ix].children()[1].abspid()!=321) continue;
68 LorentzTransform boost1 = LorentzTransform::mkFrameTransformFromBeta(LAMBDAC.decaying()[ix].momentum().betaVec());
69 FourMomentum pbaryon1 = boost1.transform(LAMBDAC.decaying()[ix].momentum());
70 FourMomentum pbaryon2 = boost1.transform(lam.momentum());
71 LorentzTransform boost2 = LorentzTransform::mkFrameTransformFromBeta(pbaryon1.betaVec());
72 Vector3 axis = pbaryon1.p3().unit();
73 FourMomentum pp = boost2.transform(pbaryon2);
74 // calculate angle
75 double cTheta = pp.p3().unit().dot(axis);
76 _h_ctheta[0]->fill(cTheta);
77 _h_ctheta[1]->fill(cTheta);
78 }
79 }
80
81
82 /// Normalise histograms etc., after the run
83 void finalize() {
84 for(unsigned int ix=0;ix<3;++ix)
85 normalize(_h_mass [ix]);
86 for(unsigned int ix=0;ix<2;++ix)
87 normalize(_h_ctheta[ix]);
88 }
89
90 /// @}
91
92
93 /// @name Histograms
94 /// @{
95 Histo1DPtr _h_mass [3];
96 Histo1DPtr _h_ctheta[2];
97 /// @}
98
99
100 };
101
102
103 RIVET_DECLARE_PLUGIN(BABAR_2006_I722213);
104
105}
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