Rivet analyses referenceBESIII_2021_I1845444Mass distributions in the decayExperiment: BESIII (BEPC) Inspire ID: 1845444 Status: VALIDATED NOHEPDATA Authors:
Beam energies: ANY
Measurement of the mass distributions in the decay by BES. The data were read from the plots in the paper and therefore for some points the error bars are the size of the point. It is also not clear that any resolution effects have been unfolded. Source code: BESIII_2021_I1845444.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 Ds -> KS0 K-pi+pi+
10 class BESIII_2021_I1845444 : public Analysis {
11 public:
12
13 /// Constructor
14 RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2021_I1845444);
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==431);
24 declare(ufs, "UFS");
25 DecayedParticles DS(ufs);
26 DS.addStable(PID::PI0);
27 DS.addStable(PID::K0S);
28 declare(DS,"DS");
29 // histos
30 for(unsigned int ix=0;ix<9;++ix)
31 book(_h[ix],1,1,1+ix);
32 }
33
34 /// Perform the per-event analysis
35 void analyze(const Event& event) {
36 static const map<PdgId,unsigned int> & mode = { { 211,2}, {-321,1}, {310,1}};
37 static const map<PdgId,unsigned int> & modeCC = { {-211,2}, { 321,1}, {310,1}};
38 DecayedParticles DS = apply<DecayedParticles>(event, "DS");
39 // loop over particles
40 for(unsigned int ix=0;ix<DS.decaying().size();++ix) {
41 int sign = 1;
42 if (DS.decaying()[ix].pid()>0 && DS.modeMatches(ix,4,mode)) {
43 sign=1;
44 }
45 else if (DS.decaying()[ix].pid()<0 && DS.modeMatches(ix,4,modeCC)) {
46 sign=-1;
47 }
48 else
49 continue;
50 const Particle & Km = DS.decayProducts()[ix].at(-sign*321)[0];
51 const Particles & pip = DS.decayProducts()[ix].at( sign*211);
52 const Particle & K0 = DS.decayProducts()[ix].at( 310)[0];
53 double mK0pi[2] = {(K0.momentum()+pip[0].momentum()).mass(),
54 (K0.momentum()+pip[1].momentum()).mass()};
55 unsigned int i0(0),i1(1);
56 if(mK0pi[i0]>mK0pi[i1]) swap(i0,i1);
57 _h[0]->fill((K0 .momentum()+Km .momentum()).mass());
58 _h[1]->fill(mK0pi[i0]);
59 _h[2]->fill((Km .momentum()+pip[i1].momentum()).mass());
60 _h[3]->fill(mK0pi[i1]);
61 _h[4]->fill((Km .momentum()+pip[i0].momentum()).mass());
62 _h[5]->fill((K0 .momentum()+Km .momentum()+pip[i0].momentum()).mass());
63 _h[6]->fill((K0 .momentum()+Km .momentum()+pip[i1].momentum()).mass());
64 _h[7]->fill((pip[i0].momentum()+pip[i1].momentum()).mass());
65 _h[8]->fill((Km .momentum()+pip[i0].momentum()+pip[i1].momentum()).mass());
66 }
67 }
68
69
70 /// Normalise histograms etc., after the run
71 void finalize() {
72 for(unsigned int ix=0;ix<9;++ix)
73 normalize(_h[ix],1.,false);
74 }
75
76 /// @}
77
78
79 /// @name Histograms
80 /// @{
81 Histo1DPtr _h[9];
82 /// @}
83
84
85 };
86
87
88 RIVET_DECLARE_PLUGIN(BESIII_2021_I1845444);
89
90}
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