Rivet analyses referenceFOCUS_2007_I741543Mass distributions in the decay $D^0\to \pi^+\pi^-\pi^+\pi^-$Experiment: FOCUS (Fermilab) Inspire ID: 741543 Status: VALIDATED NOHEPDATA Authors:
Beam energies: ANY Run details:
Measurement of the mass distributions in the decay $D^0\to \pi^+\pi^-\pi^+\pi^-$ and $D^0\to K^+K^-\pi^+\pi^-$ by the FOCUS collaboration. 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: FOCUS_2007_I741543.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 D0 -> 2pi+2pi-
10 class FOCUS_2007_I741543 : public Analysis {
11 public:
12
13 /// Constructor
14 RIVET_DEFAULT_ANALYSIS_CTOR(FOCUS_2007_I741543);
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<4;++ix)
33 book(_h[ix ],1,1,1+ix);
34 book(_h[4],2,1,1);
35 }
36
37
38 /// Perform the per-event analysis
39 void analyze(const Event& event) {
40 // define the decay mode
41 static const map<PdgId,unsigned int> & mode1 = { { 211,2}, { -211,2}};
42 DecayedParticles D0 = apply<DecayedParticles>(event, "D0");
43 // loop over particles
44 for(unsigned int ix=0;ix<D0.decaying().size();++ix) {
45 int sign = D0.decaying()[ix].pid()/421;
46 if ( D0.modeMatches(ix,4,mode1)) {
47 const Particles & pip= D0.decayProducts()[ix].at( sign*211);
48 const Particles & pim= D0.decayProducts()[ix].at(-sign*211);
49 set<double> mpm;
50 for(unsigned int ix=0;ix<2;++ix) {
51 for(unsigned int iy=0;iy<2;++iy) {
52 double m = (pip[ix].momentum()+pim[iy].momentum()).mass();
53 _h[0]->fill(m);
54 mpm.insert(m);
55 }
56 }
57 _h[1]->fill(*mpm.rbegin());
58 _h[2]->fill(*mpm.begin());
59 FourMomentum ppp = pip[0].momentum()+pip[1].momentum();
60 _h[3]->fill(ppp.mass());
61 FourMomentum pmm = pim[0].momentum()+pim[1].momentum();
62 _h[3]->fill(pmm.mass());
63 for(unsigned int ix=0;ix<2;++ix) {
64 _h[4]->fill((ppp+pim[ix].momentum()).mass());
65 _h[4]->fill((pmm+pip[ix].momentum()).mass());
66 }
67 }
68 }
69 }
70
71
72 /// Normalise histograms etc., after the run
73 void finalize() {
74 for(unsigned int ix=0;ix<5;++ix)
75 normalize(_h[ix],1.,false);
76 }
77
78 /// @}
79
80
81 /// @name Histograms
82 /// @{
83 Histo1DPtr _h[5];
84 /// @}
85
86
87 };
88
89
90 RIVET_DECLARE_PLUGIN(FOCUS_2007_I741543);
91
92}
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