Rivet analyses referenceLHCB_2018_I1704426Mass distributions in the decays $D^0\to K^+K^-\pi^+\pi^-$Experiment: LHCB (LHC) Inspire ID: 1704426 Status: VALIDATED NOHEPDATA Authors:
Beam energies: ANY Run details:
Measurement of the mass distributions in the decay $D^0\to K^+K^-\pi^+\pi^-$ by LHCb. The data were extracted from the plots in the paper. It is also not clear that any resolution effects have been unfolded. Source code: LHCB_2018_I1704426.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
10 class LHCB_2018_I1704426 : public Analysis {
11 public:
12
13 /// Constructor
14 RIVET_DEFAULT_ANALYSIS_CTOR(LHCB_2018_I1704426);
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==421);
24 declare(ufs, "UFS");
25 DecayedParticles D0(ufs);
26 D0.addStable(PID::PI0);
27 D0.addStable(PID::K0S);
28 D0.addStable(PID::ETA);
29 D0.addStable(PID::ETAPRIME);
30 declare(D0, "D0");
31 // histograms
32 for(unsigned int ix=0;ix<2;++ix)
33 book(_h[ix ],1,1,1+ix);
34 }
35
36
37 /// Perform the per-event analysis
38 void analyze(const Event& event) {
39 // define the decay mode
40 static const map<PdgId,unsigned int> & mode = { { 321,1}, { -321,1}, { 211,1}, { -211,1}};
41 DecayedParticles D0 = apply<DecayedParticles>(event, "D0");
42 // loop over particles
43 for(unsigned int ix=0;ix<D0.decaying().size();++ix) {
44 int sign = D0.decaying()[ix].pid()/421;
45 if ( D0.modeMatches(ix,4,mode)) {
46 const Particles & Kp = D0.decayProducts()[ix].at( sign*321);
47 const Particles & Km = D0.decayProducts()[ix].at(-sign*321);
48 const Particles & pip= D0.decayProducts()[ix].at( sign*211);
49 const Particles & pim= D0.decayProducts()[ix].at(-sign*211);
50 double mpipi = (pip[0].momentum()+pim[0].momentum()).mass();
51 if(mpipi>0.4802 && mpipi<0.5072) continue;
52 _h[0]->fill((Kp [0].momentum()+Km [0].momentum()).mass()/MeV);
53 _h[1]->fill(mpipi/MeV);
54 }
55 }
56 }
57
58
59 /// Normalise histograms etc., after the run
60 void finalize() {
61 for(unsigned int ix=0;ix<2;++ix)
62 normalize(_h[ix],1.,false);
63 }
64
65 /// @}
66
67
68 /// @name Histograms
69 /// @{
70 Histo1DPtr _h[2];
71 /// @}
72
73
74 };
75
76
77 RIVET_DECLARE_PLUGIN(LHCB_2018_I1704426);
78
79}
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