Rivet analyses referenceBESIII_2023_I2621481$D^{0,+}\to\pi^+\pi^+\pi^-+X$ decaysExperiment: BESIII (BEPC) Inspire ID: 2621481 Status: VALIDATED NOHEPDATA Authors:
Beam energies: (2.4, 2.4) GeV Run details:
Measurement of mass and momentum distributions in $D^{0,+}\to\pi^+\pi^+\pi^-+X$ decays. The mass distribution was read from table VII in the paper and is corrected while the momentum distributions were extracted from the figures and are background subtracted but not corrected. Source code: BESIII_2023_I2621481.cc 1// -*- C++ -*-
2#include "Rivet/Analysis.hh"
3#include "Rivet/Projections/UnstableParticles.hh"
4
5namespace Rivet {
6
7
8 /// @brief D0,+ -> pi+ pi+ pi- +X
9 class BESIII_2023_I2621481 : public Analysis {
10 public:
11
12 /// Constructor
13 RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2023_I2621481);
14
15
16 /// @name Analysis methods
17 /// @{
18
19 /// Book histograms and initialise projections before the run
20 void init() {
21 // projections
22 declare(UnstableParticles(Cuts::abspid==411 or
23 Cuts::abspid==421),"UFS");
24 // histos
25 for(unsigned int ix=0;ix<2;++ix) {
26 book(_h_br [ix],1,1,1+ix);
27 book(_h_mass[ix],2,1,1+ix);
28 for(unsigned int iy=0;iy<3;++iy)
29 book(_h_mom[ix][iy],3,1+ix,1+iy);
30 book(_c[ix],"TMP/nD_"+toString(ix+1));
31 }
32 }
33
34 void findChildren(const Particle & p, Particles & piPlus, Particles & piMinus) {
35 for( const Particle &child : p.children()) {
36 if(child.pid()==PID::PIPLUS) {
37 piPlus.push_back(child);
38 }
39 else if(child.pid()==PID::PIMINUS) {
40 piMinus.push_back(child);
41 }
42 else if(child.pid()==PID::K0S || child.pid()==PID::K0L)
43 continue;
44 else if(!child.children().empty())
45 findChildren(child,piPlus,piMinus);
46 }
47 }
48
49 /// Perform the per-event analysis
50 void analyze(const Event& event) {
51 for (const Particle& p : apply<FinalState>(event, "UFS").particles()) {
52 unsigned int iloc = p.abspid()==421 ? 0 : 1;
53 _c[iloc]->fill();
54 Particles piPlus,piMinus;
55 findChildren(p,piPlus,piMinus);
56 if(p.pid()<0) swap(piPlus,piMinus);
57 if(piPlus.size()>=2 && !piMinus.empty()) {
58 _h_br[iloc]->fill(.5);
59 sortBy(piMinus,cmpMomByP);
60 sortBy(piPlus ,cmpMomByP);
61 _h_mom[iloc][2]->fill(piMinus[0].p3().mod());
62 for(unsigned int ix=0;ix<2;++ix)
63 _h_mom[iloc][ix]->fill(piPlus[ix].p3().mod());
64 double mass = (piMinus[0].momentum()+piPlus[0].momentum()+piPlus[1].momentum()).mass();
65 _h_mass[iloc]->fill(mass);
66 }
67 }
68 }
69
70 /// Normalise histograms etc., after the run
71 void finalize() {
72 for(unsigned int ix=0;ix<2;++ix) {
73 scale(_h_br [ix], 100./ *_c[ix]);
74 scale(_h_mass[ix], 100./ *_c[ix]);
75 for(unsigned int iy=0;iy<3;++iy)
76 normalize(_h_mom[ix][iy],1.,false);
77 }
78 }
79
80 /// @}
81
82
83 /// @name Histograms
84 /// @{
85 Histo1DPtr _h_br[2],_h_mass[2],_h_mom[2][3];
86 CounterPtr _c[2];
87 /// @}
88
89
90 };
91
92
93 RIVET_DECLARE_PLUGIN(BESIII_2023_I2621481);
94
95}
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