Rivet analyses referenceBESIII_2019_I1711896Mass distributions in $\Lambda_c^+\to\Lambda^0\eta\pi^+$Experiment: BESIII (BEPC) Inspire ID: 1711896 Status: VALIDATED NOHEPDATA Authors:
Beam energies: ANY Run details:
Measurement of the mass distributions in the decay $\Lambda_c^+\to\Lambda^0\eta\pi^+$ byt BESIII. The data were read from the plots in the paper, it is not clear that any resolution/efficiency effects have been unfolded. Source code: BESIII_2019_I1711896.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 eta pi+
10 class BESIII_2019_I1711896 : public Analysis {
11 public:
12
13 /// Constructor
14 RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2019_I1711896);
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::ETAPRIME);
30 LAMBDAC.addStable(PID::LAMBDA);
31 declare(LAMBDAC, "LAMBDAC");
32 // histograms
33 book(_h,1,1,1);
34 book(_dalitz, "dalitz",50,1.5,3.5,50,2.5,5.0);
35 }
36
37
38 /// Perform the per-event analysis
39 void analyze(const Event& event) {
40 static const map<PdgId,unsigned int> & mode = { { 211,1},{ 221,1}, { PID::LAMBDA,1}};
41 static const map<PdgId,unsigned int> & modeCC = { {-211,1},{ 221,1}, {-PID::LAMBDA,1}};
42 DecayedParticles LAMBDAC = apply<DecayedParticles>(event, "LAMBDAC");
43 // loop over particles
44 for(unsigned int ix=0;ix<LAMBDAC.decaying().size();++ix) {
45 int sign = 1;
46 if (LAMBDAC.decaying()[ix].pid()>0 && LAMBDAC.modeMatches(ix,3,mode)) {
47 sign=1;
48 }
49 else if (LAMBDAC.decaying()[ix].pid()<0 && LAMBDAC.modeMatches(ix,3,modeCC)) {
50 sign=-1;
51 }
52 else
53 continue;
54 const Particles & lam = LAMBDAC.decayProducts()[ix].at( sign*PID::LAMBDA);
55 const Particles & pip = LAMBDAC.decayProducts()[ix].at( sign*PID::PIPLUS);
56 const Particles & eta = LAMBDAC.decayProducts()[ix].at( PID::ETA);
57 double mLamPi = (lam[0].momentum()+pip[0].momentum()).mass2();
58 double mLamEta = (lam[0].momentum()+eta[0].momentum()).mass2();
59 _dalitz ->fill(mLamPi,mLamEta);
60 _h->fill(sqrt(mLamPi));
61 }
62 }
63
64
65 /// Normalise histograms etc., after the run
66 void finalize() {
67 normalize(_h);
68 normalize(_dalitz );
69 }
70
71 /// @}
72
73
74 /// @name Histograms
75 /// @{
76 Histo1DPtr _h;
77 Histo2DPtr _dalitz;
78 /// @}
79
80
81 };
82
83
84 RIVET_DECLARE_PLUGIN(BESIII_2019_I1711896);
85
86}
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