rivet is hosted by Hepforge, IPPP Durham

Rivet analyses reference

BESIII_2021_I1929365

Dalitz plot analysis of $D_s^+\to \pi^+\pi^0\pi^0$
Experiment: BESIII (BEPC)
Inspire ID: 1929365
Status: VALIDATED NOHEPDATA
Authors:
  • Peter Richardson
References:
  • JHEP 01 (2022) 052
Beams: * *
Beam energies: ANY
    No run details listed

Measurement of the mass distributions in the decay $D_s^+\to \pi^+\pi^0\pi^0$. 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: BESIII_2021_I1929365.cc 
 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
// -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/UnstableParticles.hh"
#include "Rivet/Projections/DecayedParticles.hh"

namespace Rivet {


  /// @brief D_s+ -> pi+ pi0 pi0
  class BESIII_2021_I1929365 : public Analysis {
  public:

    /// Constructor
    RIVET_DEFAULT_ANALYSIS_CTOR(BESIII_2021_I1929365);


    /// @name Analysis methods
    /// @{

    /// Book histograms and initialise projections before the run
    void init() {
      // Initialise and register projections
      UnstableParticles ufs = UnstableParticles(Cuts::abspid==431);
      declare(ufs, "UFS");
      DecayedParticles DS(ufs);
      DS.addStable(PID::PI0);
      DS.addStable(PID::K0S);
      declare(DS,"DS");
      // histos
      book(_h_pi0pi0,1,1,1);
      book(_h_pippi0,1,1,2);
      book(_dalitz, "dalitz",50,0.,3.5,50,0.,3.5);
    }

    /// Perform the per-event analysis
    void analyze(const Event& event) {
      static const map<PdgId,unsigned int> & mode   = { { 211,1},{ 111,2}};
      static const map<PdgId,unsigned int> & modeCC = { {-211,1},{ 111,2}};
      DecayedParticles DS = apply<DecayedParticles>(event, "DS");
      // loop over particles
      for(unsigned int ix=0;ix<DS.decaying().size();++ix) {
	int sign = 1;
	if (DS.decaying()[ix].pid()>0 && DS.modeMatches(ix,3,mode)) {
	  sign=1;
	}
	else if  (DS.decaying()[ix].pid()<0 && DS.modeMatches(ix,3,modeCC)) {
	  sign=-1;
	}
	else
	  continue;
	const Particles & pi0 = DS.decayProducts()[ix].at(      111);
	const Particle  & pip = DS.decayProducts()[ix].at( sign*211)[0];
	double mp1  = (pip   .momentum() +pi0[0].momentum()).mass2();
	double mp2  = (pip   .momentum() +pi0[1].momentum()).mass2();
	double m0   = (pi0[0].momentum() +pi0[1].momentum()).mass();
	_dalitz ->fill(mp1,mp2);
	_dalitz ->fill(mp2,mp1);
	// K_S0 veto
	if(m0>0.458 && m0<0.520) continue;
	_h_pippi0->fill(sqrt(mp1));
	_h_pippi0->fill(sqrt(mp2));
	_h_pi0pi0->fill(m0 );
      }
    }


    /// Normalise histograms etc., after the run
    void finalize() {
      normalize(_h_pi0pi0);
      normalize(_h_pippi0);
      normalize(_dalitz  );
    }

    /// @}


    /// @name Histograms
    /// @{
    Histo1DPtr _h_pi0pi0,_h_pippi0;
    Histo2DPtr _dalitz;
    /// @}


  };


  RIVET_DECLARE_PLUGIN(BESIII_2021_I1929365);

}