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
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221 | // -*- C++ -*-
#include "Rivet/Analysis.hh"
#include "Rivet/Projections/UnstableParticles.hh"
#include "Rivet/Projections/DecayedParticles.hh"
namespace Rivet {
/// @brief B -> D* omega pi
class BELLE_2015_I1369998 : public Analysis {
public:
/// Constructor
RIVET_DEFAULT_ANALYSIS_CTOR(BELLE_2015_I1369998);
/// @name Analysis methods
/// @{
/// Book histograms and initialise projections before the run
void init() {
UnstableParticles ufs = UnstableParticles(Cuts::abspid==511);
declare(ufs, "UFS");
DecayedParticles B0(ufs);
B0.addStable( 413);
B0.addStable(-413);
B0.addStable( 223);
declare(B0, "B0");
for(unsigned int ix=0;ix<4;++ix)
for(unsigned int iy=0;iy<6;++iy)
book(_h[ix][iy],1+ix,1,1+iy);
}
void findChildren(const Particle & p, Particles & pim, Particles & pip,
Particles & pi0, unsigned int &ncount) {
for( const Particle &child : p.children()) {
if(child.pid()==PID::PIPLUS) {
pip.push_back(child);
ncount+=1;
}
else if(child.pid()==PID::PIMINUS) {
pim.push_back(child);
ncount+=1;
}
else if(child.pid()==PID::PI0) {
pi0.push_back(child);
ncount+=1;
}
else if(child.children().empty()) {
ncount+=1;
}
else
findChildren(child,pim,pip,pi0,ncount);
}
}
/// Perform the per-event analysis
void analyze(const Event& event) {
static const map<PdgId,unsigned int> & mode = { { 413,1},{ 223,1}, {-211,1}};
static const map<PdgId,unsigned int> & modeCC = { {-413,1},{ 223,1}, { 211,1}};
DecayedParticles B0 = apply<DecayedParticles>(event, "B0");
// loop over particles
for(unsigned int ix=0;ix<B0.decaying().size();++ix) {
int sign = 1;
if(B0.decaying()[ix].pid()<0 && B0.modeMatches(ix,3,mode))
sign = 1;
else if(B0.decaying()[ix].pid()>0 && B0.modeMatches(ix,3,modeCC))
sign = -1;
else
continue;
const Particle & Dstar = B0.decayProducts()[ix].at( sign*413)[0];
const Particle & omega = B0.decayProducts()[ix].at( 223)[0];
const Particle & pim1 = B0.decayProducts()[ix].at(-sign*211)[0];
// mass hists, no cuts
double mOmegaPi2 = (omega.momentum()+pim1.momentum()).mass2();
_h[0][0]->fill(mOmegaPi2);
double mDstarpi2 = (Dstar.momentum()+pim1.momentum()).mass2();
_h[1][0]->fill(mDstarpi2);
// check the no of decay products
if(Dstar.children().size()!=2 || omega.children().size()!=3)
continue;
// find the children of the D* meson
Particle D0,pip1;
if(Dstar.children()[0].pid()==sign*211 &&
Dstar.children()[1].pid()==sign*421) {
pip1 = Dstar.children()[0];
D0 = Dstar.children()[1];
}
else if(Dstar.children()[1].pid()==sign*211 &&
Dstar.children()[0].pid()==sign*421) {
pip1 = Dstar.children()[1];
D0 = Dstar.children()[0];
}
else
continue;
// children of the omega
unsigned int ncount=0;
Particles pip,pim,pi0;
findChildren(omega,pim,pip,pi0,ncount);
if( ncount!=3 || !(pim.size()==1 && pip.size()==1 && pi0.size()==1)) continue;
// first bottom to the B frame
LorentzTransform boostB = LorentzTransform::mkFrameTransformFromBeta(B0.decaying()[ix].momentum().betaVec());
FourMomentum pOmega = boostB.transform(omega.momentum());
FourMomentum pDstar = boostB.transform(Dstar.momentum());
FourMomentum pD = boostB.transform(D0 .momentum());
FourMomentum ppim1 = boostB.transform(pim1 .momentum());
FourMomentum ppim2 = boostB.transform(pim[0].momentum());
FourMomentum ppip1 = boostB.transform(pip1 .momentum());
FourMomentum ppip2 = boostB.transform(pip[0].momentum());
// ---------------------- First set of angles --------------------------------------
// first the angles for D* (pi omega)
LorentzTransform boostD = LorentzTransform::mkFrameTransformFromBeta(pDstar.betaVec());
Vector3 axisD = boostD.transform(pD ).p3().unit();
Vector3 axispip1 = boostD.transform(ppip1).p3().unit();
Vector3 axisDstar = (pOmega+ppim1).p3().unit();
double cBeta1 = axisDstar.dot(axisD);
_h[0][3]->fill(cBeta1);
LorentzTransform boostWpi = LorentzTransform::mkFrameTransformFromBeta((pOmega+ppim1).betaVec());
FourMomentum pOmega2 = boostWpi.transform(pOmega);
Vector3 axisW = pOmega2.p3().unit();
Vector3 axisWpi = (pOmega+ppim1).p3().unit();
double cXi1 = axisWpi.dot(axisW);
_h[0][1]->fill(cXi1);
// now angle between the two planes
Vector3 transW = axisW-cXi1*axisWpi;
Vector3 transD = axisD-cBeta1*axisDstar;
double psi1 = atan2(transW.cross(transD).dot(axisDstar), transW.dot(transD));
_h[0][5]->fill(psi1);
// normal to omega decay plane
LorentzTransform boostW = LorentzTransform::mkFrameTransformFromBeta(pOmega2.betaVec());
FourMomentum ppim3 = boostW.transform(boostWpi.transform(ppim2));
FourMomentum ppip3 = boostW.transform(boostWpi.transform(ppip2));
Vector3 nW = ppim3.p3().cross(ppip3.p3()).unit();
// boost B decay products to omega rest frame
FourMomentum pOmegaPi = boostW.transform(boostWpi.transform(pOmega+ppim1));
FourMomentum pDstar2 = boostW.transform(boostWpi.transform(pDstar));
Vector3 axisWpi2 = pOmegaPi.p3().unit();
double cTheta1 = axisWpi2.dot(nW);
transW = nW-cTheta1*axisWpi2;
transD = pDstar2.p3().unit()-pDstar2.p3().unit().dot(axisWpi2)*axisWpi2;
double phi1 = atan2(transW.cross(transD).dot(axisWpi2), transW.dot(transD));
_h[0][2]->fill(cTheta1);
_h[0][4]->fill(phi1);
// ---------------------- Second set of angles --------------------------------------
// boost to D* pi frame
LorentzTransform boostDpi = LorentzTransform::mkFrameTransformFromBeta((pDstar+ppim1).betaVec());
pDstar2 = boostDpi.transform(pDstar);
pOmega2 = boostDpi.transform(pOmega);
axisW = pOmega2.p3().unit();
axisDstar = pDstar2.p3().unit();
double cXi2 = axisW.dot(axisDstar);
_h[1][1]->fill(cXi2);
// boost to D* rest frame
LorentzTransform boostDstar = LorentzTransform::mkFrameTransformFromBeta(pDstar2.betaVec());
axisW = boostDstar.transform(pOmega2).p3().unit();
Vector3 axisDSpi= boostDstar.transform(boostDpi.transform(pDstar+ppim1)).p3().unit();
axisD= boostDstar.transform(boostDpi.transform(pD)).p3().unit();
double cBeta2 = axisD.dot(axisDSpi);
_h[1][3]->fill(cBeta2);
transW = axisW-axisW.dot(axisDSpi)*axisDSpi;
transD = axisD-cBeta2*axisDSpi;
double psi2 = atan2(transW.cross(transD).dot(axisDSpi), transW.dot(transD));
_h[1][5]->fill(psi2);
// boost to omega frame
boostW = LorentzTransform::mkFrameTransformFromBeta(pOmega.betaVec());
ppim3 = boostW.transform(ppim2);
ppip3 = boostW.transform(ppip2);
nW = ppim3.p3().cross(ppip3.p3()).unit();
axisDSpi = boostW.transform(pDstar+ppim1).p3().unit();
axisDstar = boostW.transform(pDstar).p3().unit();
double cTheta2 = axisDSpi.dot(nW);
_h[1][2]->fill(cTheta2);
transW = nW-cTheta2*axisDSpi;
transD = axisDstar.unit()-axisDstar.dot(axisDSpi)*axisDSpi;
double phi2 = atan2(transW.cross(transD).dot(axisDSpi), transW.dot(transD));
_h[1][4]->fill(psi2);
// restricted plots
if(abs(cTheta1)>.5) {
_h[2][0]->fill(mOmegaPi2);
}
else {
_h[2][1]->fill(mOmegaPi2);
_h[2][3]->fill(cBeta1);
_h[2][5]->fill(psi1);
_h[3][1]->fill(mDstarpi2);
_h[3][3]->fill(cTheta2);
_h[3][5]->fill(phi2);
}
if(cXi2>-.4) {
_h[2][2]->fill(cBeta1);
_h[2][4]->fill(psi1);
_h[3][0]->fill(mDstarpi2);
_h[3][2]->fill(cTheta2);
_h[3][4]->fill(phi2);
}
}
}
/// Normalise histograms etc., after the run
void finalize() {
for(unsigned int ix=0;ix<4;++ix)
for(unsigned int iy=0;iy<6;++iy)
normalize(_h[ix][iy],1.,false);
}
/// @}
/// @name Histograms
/// @{
Histo1DPtr _h[4][6];
/// @}
};
RIVET_DECLARE_PLUGIN(BELLE_2015_I1369998);
}
|