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
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
| // -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/UnstableParticles.hh"
namespace Rivet {
/// @brief Xi_c0 decay asymmetries
class BELLE_2021_I1859517 : public Analysis {
public:
/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BELLE_2021_I1859517);
/// @name Analysis methods
///@{
/// Book histograms and initialise projections before the run
void init() {
// Initialise and register projections
declare(UnstableParticles(), "UFS" );
// book histograms
book(_h_Lambda,1,1,1);
book(_h_Sigma0,2,1,1);
book(_h_Sigmap,3,1,1);
}
/// Perform the per-event analysis
void analyze(const Event& event) {
// loop over Xi_c0 baryons
for( const Particle& Xic : apply<UnstableParticles>(event, "UFS").particles(Cuts::abspid==4132)) {
int sign = Xic.pid()/4132;
if(Xic.children().size()!=2) continue;
Particle baryon1,meson1;
if(Xic.children()[0].pid()==sign*3122 &&
Xic.children()[1].pid()==-sign*313) {
baryon1 = Xic.children()[0];
meson1 = Xic.children()[1];
}
else if(Xic.children()[1].pid()==sign*3122 &&
Xic.children()[0].pid()==-sign*313) {
baryon1 = Xic.children()[1];
meson1 = Xic.children()[0];
}
else if(Xic.children()[0].pid()==sign*3212 &&
Xic.children()[1].pid()==-sign*313) {
baryon1 = Xic.children()[0];
meson1 = Xic.children()[1];
}
else if(Xic.children()[1].pid()==sign*3212 &&
Xic.children()[0].pid()==-sign*313) {
baryon1 = Xic.children()[1];
meson1 = Xic.children()[0];
}
else if(Xic.children()[0].pid()==sign*3222 &&
Xic.children()[1].pid()==-sign*323) {
baryon1 = Xic.children()[0];
meson1 = Xic.children()[1];
}
else if(Xic.children()[1].pid()==sign*3222 &&
Xic.children()[0].pid()==-sign*323) {
baryon1 = Xic.children()[1];
meson1 = Xic.children()[0];
}
else
continue;
Particle baryon2,meson2;
if(baryon1.abspid()==3122) {
if(baryon1.children()[0].pid()== sign*2212 &&
baryon1.children()[1].pid()==-sign*211) {
baryon2 = baryon1.children()[0];
meson2 = baryon1.children()[1];
}
else if(baryon1.children()[1].pid()== sign*2212 &&
baryon1.children()[0].pid()==-sign*211) {
baryon2 = baryon1.children()[1];
meson2 = baryon1.children()[0];
}
else
continue;
}
else if(baryon1.abspid()==3212) {
if(baryon1.children()[0].pid()== sign*3122 &&
baryon1.children()[1].pid()==22) {
baryon2 = baryon1.children()[0];
meson2 = baryon1.children()[1];
}
else if(baryon1.children()[1].pid()== sign*3122 &&
baryon1.children()[0].pid()==22) {
baryon2 = baryon1.children()[1];
meson2 = baryon1.children()[0];
}
else
continue;
}
else if(baryon1.abspid()==3222) {
if(baryon1.children()[0].pid()== sign*2212 &&
baryon1.children()[1].pid()==111) {
baryon2 = baryon1.children()[0];
meson2 = baryon1.children()[1];
}
else if(baryon1.children()[1].pid()== sign*2212 &&
baryon1.children()[0].pid()==111) {
baryon2 = baryon1.children()[1];
meson2 = baryon1.children()[0];
}
else
continue;
}
// first boost to the Xic rest frame
LorentzTransform boost1 = LorentzTransform::mkFrameTransformFromBeta(Xic.momentum().betaVec());
FourMomentum pbaryon1 = boost1.transform(baryon1.momentum());
FourMomentum pbaryon2 = boost1.transform(baryon2.momentum());
// to lambda rest frame
LorentzTransform boost2 = LorentzTransform::mkFrameTransformFromBeta(pbaryon1.betaVec());
Vector3 axis = pbaryon1.p3().unit();
FourMomentum pp = boost2.transform(pbaryon2);
// calculate angle
double cTheta = pp.p3().unit().dot(axis);
if(baryon1.abspid()==3122) {
_h_Lambda->fill(cTheta);
}
else if(baryon1.abspid()==3212) {
_h_Sigma0->fill(cTheta);
}
else if(baryon1.abspid()==3222) {
_h_Sigmap->fill(cTheta);
}
}
}
pair<double,double> calcAlpha(Histo1DPtr hist) {
if(hist->numEntries()==0.) return make_pair(0.,0.);
double sum1(0.),sum2(0.);
for (auto bin : hist->bins() ) {
double Oi = bin.area();
if(Oi==0.) continue;
double ai = 0.5*(bin.xMax()-bin.xMin());
double bi = 0.5*ai*(bin.xMax()+bin.xMin());
double Ei = bin.areaErr();
sum1 += sqr(bi/Ei);
sum2 += bi/sqr(Ei)*(Oi-ai);
}
return make_pair(sum2/sum1,sqrt(1./sum1));
}
/// Normalise histograms etc., after the run
void finalize() {
// Lambda Kbar*0
normalize(_h_Lambda);
Scatter2DPtr _h_alpha;
book(_h_alpha,4,1,1);
pair<double,double> alpha = calcAlpha(_h_Lambda);
_h_alpha->addPoint(0.5, alpha.first, make_pair(0.5,0.5), make_pair(alpha.second,alpha.second) );
// Sigma0 Kbar*0
normalize(_h_Sigma0);
book(_h_alpha,4,1,2);
alpha = calcAlpha(_h_Sigma0);
_h_alpha->addPoint(0.5, alpha.first, make_pair(0.5,0.5), make_pair(alpha.second,alpha.second) );
// Sigma+ K*-
normalize(_h_Sigmap);
book(_h_alpha,4,1,3);
alpha = calcAlpha(_h_Sigmap);
_h_alpha->addPoint(0.5, alpha.first, make_pair(0.5,0.5), make_pair(alpha.second,alpha.second) );
}
///@}
/// @name Histograms
///@{
Histo1DPtr _h_Lambda,_h_Sigma0,_h_Sigmap;
///@}
};
RIVET_DECLARE_PLUGIN(BELLE_2021_I1859517);
}
|