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FOCUS_2007_I750701

Dalitz plot analysis of $D^+\to K^-\pi^+\pi^+$
Experiment: FOCUS (Fermilab)
Inspire ID: 750701
Status: VALIDATED NOHEPDATA
Authors:
  • Peter Richardson
References:
  • Phys.Lett.B 653 (2007) 1-11
Beams: * *
Beam energies: ANY
Run details:
  • Any process producing D+ -> K- pi+ pi+

Measurement of the mass distributions in the decay $D^+\to K^-\pi^+\pi^+$. The data were read from the plots in the paper. Resolution/acceptance effects have been not unfolded and given the agreement with the model in the paper this analysis should only be used for qualitative studies.

Source code: FOCUS_2007_I750701.cc
 1// -*- C++ -*-
 2#include "Rivet/Analysis.hh"
 3#include "Rivet/Projections/DecayedParticles.hh"
 4#include "Rivet/Projections/UnstableParticles.hh"
 5
 6namespace Rivet {
 7
 8
 9  /// @brief D+ -> K-pi+pi+
10  class FOCUS_2007_I750701 : public Analysis {
11  public:
12
13    /// Constructor
14    RIVET_DEFAULT_ANALYSIS_CTOR(FOCUS_2007_I750701);
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== 411);
24      declare(ufs, "UFS");
25      DecayedParticles DP(ufs);
26      DP.addStable(PID::PI0);
27      declare(DP, "DP");
28      // histos
29      book(_h_low,1,1,1);
30      book(_h_high,1,1,2);
31      book(_dalitz, "dalitz",50,0.,3.1,50,0.3,3.1);
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} };
37      static const map<PdgId,unsigned int> & modeCC = { {-211,2}, { 321,1} };
38      // Loop over D+ mesons
39      DecayedParticles DP = apply<DecayedParticles>(event, "DP");
40      for(unsigned int ix=0;ix<DP.decaying().size();++ix) {
41	int sign = 1;
42	if     ( DP.modeMatches(ix,3,mode  )) sign = 1;
43	else if( DP.modeMatches(ix,3,modeCC)) sign =-1;
44	else
45	  continue;
46	const Particles & pip = DP.decayProducts()[ix].at( sign*211);
47	const Particle  & Km  = DP.decayProducts()[ix].at(-sign*321)[0];
48	double mplus  = (Km.momentum() +pip[0].momentum()).mass2();
49	double mminus = (Km.momentum() +pip[1].momentum()).mass2();
50	if(mplus<mminus) swap(mplus,mminus);
51	_h_low ->fill(mminus);
52	_h_high->fill(mplus );
53	_dalitz->fill(mminus,mplus );
54	_dalitz->fill(mplus ,mminus);
55      }
56    }
57
58
59    /// Normalise histograms etc., after the run
60    void finalize() {
61      normalize(_h_low );
62      normalize(_h_high);
63      normalize(_dalitz);
64    }
65
66    /// @}
67
68
69    /// @name Histograms
70    /// @{
71    Histo1DPtr _h_high,_h_low;
72    Histo2DPtr _dalitz;
73    /// @}
74
75
76  };
77
78
79  RIVET_DECLARE_PLUGIN(FOCUS_2007_I750701);
80
81}