|
|
Rivet analyses reference
BABAR_2021_I1867843
Dalitz plot analysis of $\eta_c\to K^+K^-\eta^\prime$, $\pi^+\pi^-\eta$ and $\pi^+\pi^-\eta^\prime$
Experiment: BABAR (PEP-II)
Inspire ID: 1867843
Status: VALIDATED NOHEPDATA
Authors:
References:
- Phys.Rev.D 104 (2021) 7, 072002
Beams: * *
Beam energies: ANY
Run details:
- Any process producing eta_c (originally gamma gamma -> chi_c)
Measurement of the mass distributions in the decays $\eta_c\to K^+K^-\eta^\prime$, $\pi^+\pi^-\eta$ and $\pi^+\pi^-\eta^\prime$ by BaBar. The data were read from the plots in the paper and therefore for some points the error bars are the size of the point. Also the sideband background from the plots has been subtracted. It is also not clear that any resolution effects have been unfolded.
Source code:
BABAR_2021_I1867843.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
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127 | // -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/DecayedParticles.hh"
#include "Rivet/Projections/UnstableParticles.hh"
namespace Rivet {
/// @brief eta_c Dalitz decays
class BABAR_2021_I1867843 : public Analysis {
public:
/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BABAR_2021_I1867843);
/// @name Analysis methods
/// @{
/// Book histograms and initialise projections before the run
void init() {
// Initialise and register projections
UnstableParticles ufs = UnstableParticles(Cuts::pid== 441);
declare(ufs, "UFS");
DecayedParticles ETAC(ufs);
ETAC.addStable(PID::PI0);
ETAC.addStable(PID::K0S);
ETAC.addStable(PID::ETA);
ETAC.addStable(PID::ETAPRIME);
declare(ETAC,"ETAC");
// histograms
book(_h_KK ,1,1,1);
book(_h_etaPK ,1,1,2);
book(_h_pipi1 ,2,1,1);
book(_h_etaPpi,2,1,2);
book(_h_pipi2 ,3,1,1);
book(_h_etapi ,3,1,2);
book(_dalitz1, "dalitz1",50,2.,6.5,50,2.,6.5);
book(_dalitz2, "dalitz2",50,0.,9. ,50,0.,9. );
book(_dalitz3, "dalitz3",50,0.,8. ,50,0.,8. );
}
/// Perform the per-event analysis
void analyze(const Event& event) {
static const map<PdgId,unsigned int> & mode1 = { { 321,1}, {-321,1}, { 331,1}};
static const map<PdgId,unsigned int> & mode2 = { { 211,1}, {-211,1}, { 331,1}};
static const map<PdgId,unsigned int> & mode3 = { { 211,1}, {-211,1}, { 221,1}};
DecayedParticles ETAC = apply<DecayedParticles>(event, "ETAC");
// loop over particles
for(unsigned int ix=0;ix<ETAC.decaying().size();++ix) {
//K+ K- eta'
if (ETAC.modeMatches(ix,3,mode1)&&
ETAC.decaying()[ix].mass()>2.93 && ETAC.decaying()[ix].mass()<3.03) {
const Particle & Kp = ETAC.decayProducts()[ix].at( 321)[0];
const Particle & Km = ETAC.decayProducts()[ix].at(-321)[0];
const Particle & etaP = ETAC.decayProducts()[ix].at( 331)[0];
double mplus = (Kp.momentum()+etaP.momentum()).mass2();
double mminus = (Km.momentum()+etaP.momentum()).mass2();
double mKK = (Kp.momentum()+Km .momentum()).mass2();
_h_KK ->fill(sqrt(mKK));
_h_etaPK->fill(sqrt(mplus));
_h_etaPK->fill(sqrt(mminus));
_dalitz1->fill(mplus,mminus);
}
// pi+ pi- eta'
else if (ETAC.modeMatches(ix,3,mode2)&&
ETAC.decaying()[ix].mass()>2.93 && ETAC.decaying()[ix].mass()<3.03) {
const Particle & pip = ETAC.decayProducts()[ix].at( 211)[0];
const Particle & pim = ETAC.decayProducts()[ix].at(-211)[0];
const Particle & etaP = ETAC.decayProducts()[ix].at( 331)[0];
double mplus = (pip.momentum()+etaP.momentum()).mass2();
double mminus = (pim.momentum()+etaP.momentum()).mass2();
double mpipi = (pip.momentum()+pim .momentum()).mass2();
_h_pipi1 ->fill(sqrt(mpipi));
_h_etaPpi->fill(sqrt(mplus));
_h_etaPpi->fill(sqrt(mminus));
_dalitz2->fill(mplus,mminus);
}
// pi+ pi- eta
else if (ETAC.modeMatches(ix,3,mode3)&&
ETAC.decaying()[ix].mass()>2.92 && ETAC.decaying()[ix].mass()<3.02) {
const Particle & pip = ETAC.decayProducts()[ix].at( 211)[0];
const Particle & pim = ETAC.decayProducts()[ix].at(-211)[0];
const Particle & eta = ETAC.decayProducts()[ix].at( 221)[0];
double mplus = (pip.momentum()+eta.momentum()).mass2();
double mminus = (pim.momentum()+eta.momentum()).mass2();
double mpipi = (pip.momentum()+pim .momentum()).mass2();
_h_pipi2->fill(sqrt(mpipi));
_h_etapi->fill(sqrt(mplus));
_h_etapi->fill(sqrt(mminus));
_dalitz3->fill(mplus,mminus);
}
}
}
/// Normalise histograms etc., after the run
void finalize() {
normalize(_h_KK );
normalize(_h_etaPK );
normalize(_h_pipi1 );
normalize(_h_etaPpi);
normalize(_h_pipi2 );
normalize(_h_etapi );
normalize(_dalitz1 );
normalize(_dalitz2 );
normalize(_dalitz3 );
}
/// @}
/// @name Histograms
/// @{
Histo1DPtr _h_KK,_h_etaPK;
Histo1DPtr _h_pipi1,_h_etaPpi;
Histo1DPtr _h_pipi2,_h_etapi;
Histo2DPtr _dalitz1,_dalitz2,_dalitz3;
/// @}
};
RIVET_DECLARE_PLUGIN(BABAR_2021_I1867843);
}
|
|