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B0 → η′(→ ηπ+π−)K0S Time Dependent ��CP sensitivity
study for BelleII
Stefano [email protected]
INFN Padova
B2GM,Tsukuba, 21 June 2016
S.Lacaprara (INFN Padova) B0 → η
′K
0S B2GM 21/06/2016 1 / 19
Introduction and motivations
A sensitivity study for Time-Dependent CP violation analysis in theB0 → η′K0channel, a charmless b → sqq decay
CP asymmetry from time-dependentdecay rate into CP eigenstates;
B0 → η′K0is a penguin dominated mode
Precision not competitive with that from golden channel B0 → J/ψφ
Sη′K
0 = sin 2φeff1 tightly related to sin 2φ1 measured in b → css decay
identical if only penguin diagram were present: not so;I QCD factorization: ∆Sη′K 0 ∈ [−0.03, 0.03][Williamson and Zupan(2006)]
I SU(3)F approach: ∆Sη′K 0 ∈ [−0.05, 0.09][Gronau et al.(2006)]
I new physics can enter in the loop,shifting ∆Sη′K 0 more than SM expectation
B0
η′
K0
b
d
s
s
s
g
W
u, c, t
S.Lacaprara (INFN Padova) B0 → η
′K
0S B2GM 21/06/2016 2 / 19
Current results
Channel have been analyzed in B-factory[BABAR(2009), Belle(2007), Belle(2014)];
analysis based on quasi-two body approach;
sin 2φeff1 = +0.68± 0.07± 0.03 [Belle(2014)] = +0.57± 0.08± 0.02 [BABAR(2009)]
uncertainties are mostly statistical (∼ 3500 events for all final states);I syst: ±0.025 from ∆t resolution, ±0.014 from vertexing, ±0.013 from η′K0
S
fraction;
η′ K0 S
CP
HF
AG
Moriond 2
014
0.5 0.6 0.7 0.8
BaBar
PRD 79 (2009) 052003
0.57 ± 0.08 ± 0.02
Belle
JHEP 1410 (2014) 165
0.68 ± 0.07 ± 0.03
Average
HFAG correlated average
0.63 ± 0.06
H F A GH F A GMoriond 2014
PRELIMINARY
projected for 50 ab−1 σstat = 0.008, σsyst = 0.008[Urquijo(2015)]
no competition from LHCb
S.Lacaprara (INFN Padova) B0 → η
′K
0S B2GM 21/06/2016 3 / 19
Decay channels
many decay channels available B0 → η′K0
decay channel
η′ → ρ0(→ π+π−)γ BR=29% not yet
η′ → ηπ+π− 43% today
↘ η → γγ 40% ηγγ↘ η → π+π−π0 23% η3π
K 0S → π+π− 69% today
K 0S → π0π0 31% just started
K0L not yet
B0 → η′(→ηγγ /η3ππ+π−
)K0S(→π+
π−
) BR=19%
Complex final state, neutrals, large combinatorics;
final states considered so far in red
more to be studied (ρ0,K 0S → π0π0,K0
L)
S.Lacaprara (INFN Padova) B0 → η
′K
0S B2GM 21/06/2016 4 / 19
Selection
candidate selection: main cuts
Reconstruct decay chain with mass constrains for π0, η, η′, K0S,
I vertex only (w/o mass) for B0 (more later)
� π0, ηγγ :
I 0.06 < Eγ < 6 GeV, E9/E25 > 0.75
I M(π0) ∈ [100, 150] MeV
I M(ηγγ) ∈ [0.52, 0.57] GeV;
� η′ → ηγγπ+π−:
I d0(π±) < 0.08mm;z0(π±) < 0.1mm;
I N hitsPXD (π±) > 1, PID
I M(η′) ∈ [0.93, 0.98] GeV;
� η′ → η3ππ+π−:
I M(η′) ∈ [0.93, 0.98] GeV;
� K0 → π+π−:
I M(K0S → π+π−) ∈ [0.48, 0.52] GeV;
� B0 → η′(→ ηγγπ+ π−)K0
S+−
I Mbc > 5.25 GeV;
I |∆E | < 0.1 GeV;
� B0 → η′(→ η3ππ+π−)K0
S+−
I |∆E | < 0.15 GeV;
if Ncands > 1, select that with best reduced χ2 for η, η′,K0S inv. masses
S.Lacaprara (INFN Padova) B0 → η
′K
0S B2GM 21/06/2016 5 / 19
Signal distribution B0 → η′(→ η3ππ+π−)K0
S
+−
Best candidates, after selections
bcM5.25 5.255 5.26 5.265 5.27 5.275 5.28 5.285 5.291
10
210
310
410
Mbc
Best cands
" MC match
" SXF
Mbc
E∆0.2− 0.15− 0.1− 0.05− 0 0.05 0.1 0.15 0.21
10
210
310
410
ηM0.4 0.45 0.5 0.55 0.6 0.65 0.71
10
210
310
410
510
'ηM0.85 0.9 0.95 1 1.05 1.1 1.151
10
210
310
410
510
0πM0.08 0.1 0.12 0.14 0.16 0.18 0.21
10
210
310
410
/KπLL∆20− 10− 0 10 20 30 40 501
10
210
310
)-π+π(S
0) K-π+π π3
η'( η→0B
S.Lacaprara (INFN Padova) B0 → η
′K
0S B2GM 21/06/2016 6 / 19
Efficiency and combinatorics
channel ε % SxF % cands/ev
B0 → η′(→ ηγγπ+ π−)K0
S (→ π+π−) 29.4 1.1 1.06
B0 → η′(→ η3ππ+π−)K0
S(→ π+π−) 12.1 3.1 1.45
B0 → η′(→ ηγγπ+ π−)K0
S (→ π0π0) 13.5 2.2 ∼ 5
B0 → η′(→ η3ππ+π−)K0
S(→ π0π0) 6.0 3.8 ∼ 30
Efficiency drop due to π0 reco, likely to improve;
presence of π0 increase also combinatorics and signal cross feed
SxF : signal event but with wrong particle association;
B0 → η′(→ η3ππ+π−)K0
S(→ π0π0) not used in Belle and BaBaranalysis.
S.Lacaprara (INFN Padova) B0 → η
′K
0S B2GM 21/06/2016 7 / 19
Vtx reco and ∆t resolution: ηγγchannel
1 Fit the B0 vertex from charged tracks; (π± from η′ → ηπ±)2 add also constraint from reconstructed K 0
S direction; (K0S → π+π−)
3 add also constraint from B0 boost direction, transverse plane only.
(ps)truet∆t-∆10− 8− 6− 4− 2− 0 2 4 6 8 10
0
5000
10000
15000
20000
25000
/ ndf 2χ 867 / 191
Prob 0
norm 8.0e+01± 6.3e+04
CBias 0.0025±0.0307 −
Cσ 0.005± 0.629
T
Bias 0.00485±0.00735 − Tσ 0.01± 1.63
OBias 0.015± 0.132
Oσ 0.03± 4.46
Cf 0.005± 0.344
Tf 0.003± 0.443
Fit
Core
Tail
Outlier
t: 1.89 ps∆Bias: 0.01 ps
)-π+π(S
0) K-π+π γγ
η'( η→0B
Standard
(ps)truet∆t-∆10− 8− 6− 4− 2− 0 2 4 6 8 10
0
100
200
300
400
500
600
700
/ ndf 2χ 253 / 191
Prob 0.00177
norm 1.24e+01± 1.54e+03
CBias 0.013±0.047 −
Cσ 0.033± 0.587
T
Bias 0.0313±0.0524 −
T
σ 0.12± 1.47
OBias 0.080± 0.107
Oσ 0.15± 3.81
Cf 0.041± 0.393
Tf 0.028± 0.393
Fit
Core
Tail
Outlier
t: 1.62 ps∆Bias: -0.02 ps
)-π+π(S
0) K-π+π γγ
η'( η→0B
WithK0S
(ps)truet∆t-∆10− 8− 6− 4− 2− 0 2 4 6 8 10
0
5000
10000
15000
20000
25000
30000
35000
40000
/ ndf 2χ 1.02e+03 / 191
Prob 0
norm 7.8e+01± 6.1e+04
CBias 0.0013±0.0399 −
Cσ 0.002± 0.488
T
Bias 0.0036±0.0704 − Tσ 0.01± 1.14
OBias 0.018± 0.429
Oσ 0.02± 2.97
Cf 0.005± 0.565
Tf 0.004± 0.362
Fit
Core
Tail
Outlier
t: 0.91 ps∆Bias: -0.02 ps
)-π+π(S
0) K-π+π γγ
η'( η→0B
WithB0 dir.
&K0S
With beamspot (x , y) & K0S:
No efficiency lossimportant improvement in ∆tresolution1.89→ 1.62→ 0.91 ps
S.Lacaprara (INFN Padova) B0 → η
′K
0S B2GM 21/06/2016 8 / 19
Vtx reconstruction for B0 → η′(→ η3ππ+π−)K0
S+−
Standard reconstruction uses four charged tracks:π± from η′ → ηπ± and η → π±π0
(ps)truet∆t-∆10− 8− 6− 4− 2− 0 2 4 6 8 10
0
2000
4000
6000
8000
10000
12000
14000
16000
/ ndf 2χ 499 / 191
Prob 29− 2.06e
norm 5.65e+01± 3.19e+04
CBias 0.0027±0.0223 −
Cσ 0.005± 0.535
T
Bias 0.0052±0.0277 −
T
σ 0.01± 1.29
OBias 0.019± 0.266
Oσ 0.03± 3.15
Cf 0.007± 0.401
Tf 0.01± 0.46
Fit
Core
Tail
Outlier
t: 1.25 ps∆Bias: 0.02 ps
)-π+π(S
0) K-π+π π3
η'( η→0B
Standard
(ps)truet∆t-∆10− 8− 6− 4− 2− 0 2 4 6 8 10
0
2000
4000
6000
8000
10000
12000
14000
16000
18000
20000
/ ndf 2χ 629 / 191
Prob 0
norm 5.49e+01± 3.02e+04
CBias 0.002±0.036 −
Cσ 0.003± 0.445
T
Bias 0.0050±0.0562 −
T
σ 0.01± 1.07
OBias 0.021± 0.317
Oσ 0.02± 2.88
Cf 0.007± 0.565
Tf 0.006± 0.342
Fit
Core
Tail
Outlier
t: 0.88 ps∆Bias: -0.01 ps
)-π+π(S
0) K-π+π π3
η'( η→0B
WithB0 dir.
&K0S
With B0 dir. & K0S:
No efficiency loss1.25→ 0.88 psIn both cases, ∆t resolution better than in Belle, in spite of lower boost
S.Lacaprara (INFN Padova) B0 → η
′K
0S B2GM 21/06/2016 9 / 19
Backgrounds
Combinatorial: from continuum background e+e− → uu, dd , ss, ccI evaluated from Mbc side bands on real dataI now from MC production: NB: still w/o machine background!I use Continuum Suppression variable
F multivariate variables sensitive to event topologyF central (signal) vs jet-like (continuum)F past issues w/ variables “fixed”
Peaking: any other B decays possibly with real η′ and/or K0S
I evaluated from MC of generic B0B0, B+B−
F actual B0 → η′K0 removed.
Current results based on BGx0 production, namely w/o machinebackgroundI impact of machine background under studyI signal w/ machine background already produced
Next table numbers before Continuum Suppression cut
S.Lacaprara (INFN Padova) B0 → η
′K
0S B2GM 21/06/2016 10 / 19
Background reduction (before CS cut)
Sample uu dd ss cc contiuum B0B0 B+B−
Input ev (M) 1284 321 306 1063 2974 2160 2070
B0 → η′(→ ηγγπ+ π−)K0
S
+−
εsel (·10−6) 2.69 3.06 2.40 3.62 3.0 0.11 0.038
ev for 300 fb−1 1247 369 275 1445 3335 13 6
B0 → η′(→ η3ππ+π−)K0
S
+−
εsel (·10−6) 0.34 0.54 0.17 1.50 0.76 0.14 0.02
ev for 300 fb−1 166 65 20 597 847 24 3
Background reduction better for η3π than for ηγγηγγ mostly uu and ccη3π mostly cc
peaking background is smallI analyzed whole 5 ab−1 dataset from MC5
preliminary study on w/ machine background shows similar rates
S.Lacaprara (INFN Padova) B0 → η
′K
0S B2GM 21/06/2016 11 / 19
Background distributionsBest candidates, after selections
5.25 5.255 5.26 5.265 5.27 5.275 5.28 5.285 5.29
20
40
60
80
100
120
bcM
mixedcharged
uuddss
cc
0.2− 0.15− 0.1− 0.05− 0 0.05 0.1 0.15 0.2
20
40
60
80
100
120
140
160
180
200
E∆0.4 0.45 0.5 0.55 0.6 0.65 0.7
50
100
150
200
250
300
350
400
ηM
0.85 0.9 0.95 1 1.05 1.1 1.15
200
400
600
800
1000
1200
1400
1600
'ηM0.45 0.46 0.47 0.48 0.49 0.5 0.51 0.52 0.53 0.54 0.55
100
200
300
400
500
600
S0KM
20− 10− 0 10 20 30 40 50
1
10
210
/KπLL∆
)-π+π(S
0) K-π+π) γγ(η'( η→0B
S.Lacaprara (INFN Padova) B0 → η
′K
0S B2GM 21/06/2016 12 / 19
Continuum suppression
0.5− 0.4− 0.3− 0.2− 0.1− 0 0.1 0.2 0.3 0.4 0.5
50
100
150
200
250
300
350
BDTBDT
mixedchargeduuddsscc
Signal
)-π+π(S
0) K-π+π) γγ(η'( η→0B
Signal efficiency
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
Ba
ck
gro
un
d r
eje
cti
on
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
MVA Method:
BDT
Background rejection versus Signal efficiency
Working point
Tight: BDT > 0.124, εsignal = 50%, (1− εbackground ) = 97.5%,
Loose: BDT > −0.055, εsignal = 95%, (1− εbackground ) = 58%,
no cut: include the BDT in the likelihood
S.Lacaprara (INFN Padova) B0 → η
′K
0S B2GM 21/06/2016 13 / 19
Likelihood fit
Multi dim. extended maximum likelihood fit to extract S and C.
Pdf is of the form:P i
j = Tj
(∆t i , σi
∆t , ηiCP
)︸ ︷︷ ︸
time-dep part
∏k Qk,j (x
ik )︸ ︷︷ ︸
time integrated
time-dependent part, taking into account mistag rate (ηf = ±1 is CP state):
f (∆t) =e−|∆t|/τ
4τ
{1∓∆w ± (1− 2w)
×[− ηf Sf sin(∆m∆t)− Cf cos(∆m∆t)
]}
variables (xk ) used, in addition to ∆t
Mbc
∆E
Cont. Suppr.
Parameters:
effective tagging efficiency:Q = ε(1− 2w)2 = 0.33I w = 0.21, ∆w = 0.02
∆t resolution as shown previously(convoluted)
τ , ∆m from PDGS.Lacaprara (INFN Padova) B
0 → η′K
0S B2GM 21/06/2016 14 / 19
PDF fit results examples
t (ps)∆25− 20− 15− 10− 5− 0 5 10 15 20 25
Eve
nts
/ ( 1
ps
)
0
20
40
60
80
100
120
310×t"∆A RooPlot of "
/ ndf = 448.9472χ 0.00096± = -2.598130 CPC
0.0025± = -0.05562 CPS
t"∆A RooPlot of "
(GeV)bcM5.25 5.255 5.26 5.265 5.27 5.275 5.28 5.285 5.29
Eve
nts
/ ( 0
.001
GeV
)
0
10000
20000
30000
40000
50000
60000
70000
80000
90000
"bcA RooPlot of "M / ndf = 17.4532χ
0.016± = 0.800 Cf 0.000026 GeV± = 5.279880
Cµ
0.000088 GeV± = 5.277700 T
µ 0.000010 GeV± = 0.002437 Cσ 0.000022 GeV± = 0.002899 Tσ
"bcA RooPlot of "M
E (GeV)∆0.1− 0.08− 0.06− 0.04− 0.02− 0 0.02 0.04 0.06 0.08 0.1
Eve
nts
/ ( 0
.005
GeV
)
0
10000
20000
30000
40000
50000
E"∆A RooPlot of " / ndf = 9.0902χ
0.0046± = 0.7305 Cf 0.000042 GeV± = -0.0044460
Cµ
0.00016 GeV± = -0.009065 T
µ 0.000066 GeV± = 0.019073 Cσ
0.00029 GeV± = 0.04174 Tσ
E"∆A RooPlot of "
bdt0.5− 0.4− 0.3− 0.2− 0.1− 0 0.1 0.2 0.3 0.4 0.5
Eve
nts
/ ( 0
.025
)
0
10000
20000
30000
40000
50000
60000
A RooPlot of "bdt" / ndf = 1148.3152χ
0.00040± = 0.16288 µ 0.00026± = 0.12623 Lσ 0.00024± = 0.06823 Rσ
A RooPlot of "bdt"
Signal
t (ps)∆25− 20− 15− 10− 5− 0 5 10 15 20 25
Eve
nts
/ ( 1
ps
)
0
20
40
60
80
100
120
310×t"∆A RooPlot of "
/ ndf = 448.9472χ 0.00096± = -2.598130 CPC
0.0025± = -0.05562 CPS
t"∆A RooPlot of "
(GeV)bcM5.25 5.255 5.26 5.265 5.27 5.275 5.28 5.285 5.29
Eve
nts
/ ( 0
.001
GeV
)
0
200
400
600
800
1000
1200
1400
1600
1800
2000
"bcA RooPlot of "M / ndf = 9.8172χ
0.019± = 0.625 Cf 0.000083 GeV± = 5.280310
Cµ
0.00025 GeV± = 5.27408 T
µ 0.000051 GeV± = 0.003010 Cσ
0.00011 GeV± = 0.00495 Tσ
2.1± = -90.00 ξ 0.099±n = 1.036
0.0058± = 0.9238 Pf
"bcA RooPlot of "M
E (GeV)∆0.1− 0.08− 0.06− 0.04− 0.02− 0 0.02 0.04 0.06 0.08 0.1
Eve
nts
/ ( 0
.005
GeV
)
0
100
200
300
400
500
600
700
E"∆A RooPlot of " / ndf = 1.0252χ
0.0020 GeV± = -0.03822 de
µ
0.0024 GeV± = 0.1000 deσ
E"∆A RooPlot of "
bdt0.5− 0.4− 0.3− 0.2− 0.1− 0 0.1 0.2 0.3 0.4 0.5
Eve
nts
/ ( 0
.025
)
0
200
400
600
800
1000
1200
1400
1600
1800
2000
2200
A RooPlot of "bdt" / ndf = 22.3482χ
0.0021± = 0.1373 µ 0.0013± = 0.1188 Lσ 0.0013± = 0.0768 Rσ
A RooPlot of "bdt"
SxF
t (ps)∆25− 20− 15− 10− 5− 0 5 10 15 20 25
Eve
nts
/ ( 1
ps
)
0
10
20
30
40
50
60
t"∆A RooPlot of " / ndf = 1.0342χ
0.14± = 0.06 CPC
0.24± = -0.271 CPS
t"∆A RooPlot of "
(GeV)bcM5.25 5.255 5.26 5.265 5.27 5.275 5.28 5.285 5.29
Eve
nts
/ ( 0
.001
GeV
)
0
2
4
6
8
10
12
14
16
18
20
22
24
"bcA RooPlot of "M / ndf = 0.7522χ
0.00040 GeV± = 5.27838 µ 0.00035 GeV± = 0.00353 σ
69± = -90.0 ξ
0.37±n = 1.15 0.068± = 0.604 Pf
"bcA RooPlot of "M
E (GeV)∆0.1− 0.08− 0.06− 0.04− 0.02− 0 0.02 0.04 0.06 0.08 0.1
Eve
nts
/ ( 0
.005
GeV
)
0
2
4
6
8
10
12
14
16
E"∆A RooPlot of " / ndf = 0.8682χ
0.014± = 0.500 Cf 0.0053 GeV± = -0.07049
Cµ
0.0060 GeV± = 0.0269 T
µ
0.00086 GeV± = 0.03000 Cσ 0.0057 GeV± = 0.0454 Tσ
E"∆A RooPlot of "
bdt0.5− 0.4− 0.3− 0.2− 0.1− 0 0.1 0.2 0.3 0.4 0.5
Eve
nts
/ ( 0
.025
)
0
5
10
15
20
25
30
A RooPlot of "bdt" / ndf = 0.6522χ
0.020± = 0.110 µ 0.013± = 0.114 Lσ 0.012± = 0.096 Rσ
A RooPlot of "bdt"
Peaki
ngbkg
nd
t (ps)∆25− 20− 15− 10− 5− 0 5 10 15 20 25
Eve
nts
/ ( 1
ps
)
0
200
400
600
800
1000
1200
1400
1600
1800
2000
t"∆A RooPlot of " / ndf = 0.9332χ
0.016 ps± = 0.029 CBias
0.087 ps± = 0.082 TBias
0.036± = 0.800 Cf
0.0018± = 0.0045 Of
0.037 ps± = 0.273 CScale
0.13 ps± = 1.45 TScale
t"∆A RooPlot of "
(GeV)bcM5.25 5.255 5.26 5.265 5.27 5.275 5.28 5.285 5.29
Eve
nts
/ ( 0
.001
GeV
)
0
20
40
60
80
100
120
140
"bcA RooPlot of "M / ndf = 0.8272χ
4.8± = -29.87 ξ 0.000099 GeV± = 5.286950 endE
"bcA RooPlot of "M
E (GeV)∆0.1− 0.08− 0.06− 0.04− 0.02− 0 0.02 0.04 0.06 0.08 0.1
Eve
nts
/ ( 0
.005
GeV
)
0
20
40
60
80
100
120
140
E"∆A RooPlot of " / ndf = 1.1732χ
0.30± = -1.378 1
p
5.6± = -1.84 2
p
E"∆A RooPlot of "
bdt0.5− 0.4− 0.3− 0.2− 0.1− 0 0.1 0.2 0.3 0.4 0.5
Eve
nts
/ ( 0
.025
)0
50
100
150
200
250
300
350
400
450
A RooPlot of "bdt" / ndf = 0.7332χ
0.0033± = -0.10286 µ 0.0020± = 0.0493 Lσ 0.0023± = 0.1110 Rσ
A RooPlot of "bdt"
Contin
uum
∆T Mbc ∆E CS variable
S.Lacaprara (INFN Padova) B0 → η
′K
0S B2GM 21/06/2016 15 / 19
Toy MC
Testing fit machinery with Toy MC;
Yield estimated for L = 300 fb−1: N(BB) ∼ 330 · 106
I width of distribution related to the expected statistical uncertainty;I check also for bias;I input CP asymmetry parameter: S=0.7 C=0.0I testing two different CS scenarios:
F TightF LooseF No cut
I Partially embedded toysF Signal and SXF from MC;F Continuum and Peaking background from pdf;
S.Lacaprara (INFN Padova) B0 → η
′K
0S B2GM 21/06/2016 16 / 19
Toy results B0 → η′(→ ηγγπ+ π−)K0
S+−
L = 300 fb−1: Nsig = 390, Nsxf = 15, Ncont = 3300, Npeak = 30
0.2− 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.60
10
20
30
40
50
60
70
Toy results - dtSig_S Entries 1000
Mean 0.0079± 0.703
Std Dev 0.00559± 0.25
Toy results - dtSig_S
0.2− 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.60
10
20
30
40
50
60
70
80
Toy results - dtSig_S Entries 1000
Mean 0.00572± 0.703
Std Dev 0.00405± 0.181
Toy results - dtSig_S
0.2− 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.60
10
20
30
40
50
60
70
80
Toy results - dtSig_S Entries 1000
Mean 0.00563± 0.696
Std Dev 0.00398± 0.178
Toy results - dtSig_S
TightLoose
No Cut
σS = 0.26 = 0.181 = 0.178
Par Bias RMS
S (0.7) 0.696± 0.005 0.178C (0.0) 0.005± 0.004 0.13nSig 390.7± 0.8 24.7Prelim
inaryresults
Belle (772 · 106 BB): Nsig = 648, σS = 0.15, σC = 0.10
BaBar (467 · 106 BB): Nsig = 472, σS = 0.17, σC = 0.11
S.Lacaprara (INFN Padova) B0 → η
′K
0S B2GM 21/06/2016 17 / 19
Toy results B0 → η′(→ η3ππ+π−)K0
S+−
Loose
L = 300 fb−1: Nsig = 106, Nsxf = 25, Ncont = 360, Npeak = 27
0.2− 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.60
10
20
30
40
50
Toy results - dtSig_S Entries 995
Mean 0.0105± 0.708
Std Dev 0.00742± 0.33
Toy results - dtSig_S
Preliminary results:Par Bias RMS
S (0.7) 0.708± 0.010 0.330C (0.0) −0.013± 0.008 0.246nSig 110.2± 0.6 18.5
Less events due to lower BRand reduced efficiency
Belle1 (772 · 106 BB): Nsig = 104, σS = 0.21, σC = 0.18
BaBar (467 · 106 BB): Nsig = 105, σS = 0.26, σC = 0.20
1including also η′ → ρ0γS.Lacaprara (INFN Padova) B
0 → η′K
0S B2GM 21/06/2016 18 / 19
Summary
Almost a complete analysis chain for sensitivity study for ��CP inB0 → η ′K0
S channel;
Presente at last B2TIP workshop;
preliminary results are encouraging;I comparison with Belle and BaBar results looks fine;
many thing to do:I include machine background (in progress)I complete K0
S → π+π− channels;I study K0
S → π0π0 final states;
I add η′ → ρ0γK0S
+−/K0
S
00channel;
I systematics uncertainties evaluation;I documentationI . . .
manpower: a new postDoc student from Padova, Alessandro Morda, isjoining me for this work at ∼ 50%
S.Lacaprara (INFN Padova) B0 → η
′K
0S B2GM 21/06/2016 19 / 19
Additional stuff
Additional or backup slides
S.Lacaprara (INFN Padova) B0 → η
′K
0S B2GM 21/06/2016 1 / 17
Selection
good candidate selection B0 → η′(→ ηγγπ+ π−)K0
S+−
:
Reconstruct decay chain with mass constrains for η, η′, K0S,
I vertex only (w/o mass) for B0
� η → γγ :
I gamma:all: 0.06 < Eγ < 6 GeV,−150 < clustime < 0, E9/E25 > 0.75
I M(ηγγ) ∈ [0.52, 0.57] GeV;
� η′ → ηγγπ+π−:
I pi:all
I ∆logL(π,K) > −10; new
I d0(π±) < 0.08mm;
I z0(π±) < 0.1mm;
I N hitsPXD (π±) > 1
I M(η′) ∈ [0.93, 0.98] GeV;
� K0 → π+π−:
I K S0:mdst
I M(K0S → π+π−) ∈ [0.48, 0.52] GeV;
� B0 → η′(→ ηγγπ+ π−)K0
S+−
I Mbc > 5.25 GeV;
I |∆E | < 0.1 GeV;
I P-valuevtx (B0, η′,K 0
S ) > 1 · 10−5
if Ncands > 1, select candidate with highest P-valuevtx (B0, η′, η,K 0
S )
S.Lacaprara (INFN Padova) B0 → η
′K
0S B2GM 21/06/2016 2 / 17
Selection breakdonw
1.000
0.570
0.463 0.458
0.4140.392 0.378 0.378 0.376 0.370 0.361
0.3360.305 0.294
0.011
InputSkim Reco bc
M E∆ ηM
'ηM
K_SM
/K)πLogL(
∆0
d0
z N Hits vtxP TRUE
SXF0
0.2
0.4
0.6
0.8
1
Events statistics
Selections MC true /SXF
)-π+π(S
0) K-π+π γγ
η'( η→0BEvents statistics
Combinatorics
Cands mult.: 1.88Good cands mult.: 1.06
Efficiency %skim 57.0preselection 46.1good cands 30.5MC true 29.4SXF 1.1
S.Lacaprara (INFN Padova) B0 → η
′K
0S B2GM 21/06/2016 3 / 17
Signal distribution B0 → η′(→ ηγγπ+ π−)K0
S+−
bcM5.25 5.255 5.26 5.265 5.27 5.275 5.28 5.285 5.290
10000
20000
30000
40000
50000
60000
70000
Mbc
All cands
MC match
Good cands
" MC match
Mbc
E∆0.2− 0.15− 0.1− 0.05− 0 0.05 0.1 0.15 0.20
10000
20000
30000
40000
50000
60000
ηM0.4 0.45 0.5 0.55 0.6 0.65 0.70
10000
20000
30000
40000
50000
60000
70000
80000
90000
'ηM0.85 0.9 0.95 1 1.05 1.1 1.150
50
100
150
200
250
310×
S0
KM
0.45 0.46 0.47 0.48 0.49 0.5 0.51 0.52 0.53 0.54 0.551
10
210
310
410
510
/KπLL∆20− 10− 0 10 20 30 40 501
10
210
310
410
)-π+π(S
0) K-π+π γγη'( η→0B
S.Lacaprara (INFN Padova) B0 → η
′K
0S B2GM 21/06/2016 4 / 17
Signal distribution B0 → η′(→ ηγγπ+ π−)K0
S
+−
Best candidates, after selections
bcM5.25 5.255 5.26 5.265 5.27 5.275 5.28 5.285 5.290
5000
10000
15000
20000
25000
30000
35000
Mbc
Best cands
" MC match
" SXF
Mbc
E∆0.2− 0.15− 0.1− 0.05− 0 0.05 0.1 0.15 0.20
5000
10000
15000
20000
25000
30000
35000
40000
ηM0.4 0.45 0.5 0.55 0.6 0.65 0.70
10000
20000
30000
40000
50000
'ηM0.85 0.9 0.95 1 1.05 1.1 1.150
20
40
60
80
100
120
140
160
180
200
310×
S0KM
0.45 0.46 0.47 0.48 0.49 0.5 0.51 0.52 0.53 0.54 0.551
10
210
310
410
510
/KπLL∆20− 10− 0 10 20 30 40 501
10
210
310
410
)-π+π(S
0) K-π+π γγη'( η→0B
S.Lacaprara (INFN Padova) B0 → η
′K
0S B2GM 21/06/2016 5 / 17
Selection
good candidate selection B0 → η′(→ η3ππ+π−)K0
S+−
:
Reconstruct decay chain with mass constrains for η, η′, K0S,
I vertex only (w/o mass) for B0
� π0:
I gamma:all: 0.06 < Eγ < 6 GeV,−150 < clustime < 0, E9/E25 > 0.75
I M(π0) ∈ [100, 150] MeV
� η → π+π−π0:
I pi:all
I ∆logL(π,K) > −10; new
I M(η3π) ∈ [0.52, 0.57] GeV;
I d0(π±) < 0.08mm;
I z0(π±) < 0.1mm;
I N hitsPXD (π±) > 1
� η′ → η3ππ+π−:
I M(η′) ∈ [0.93, 0.98] GeV;
� K0 → π+π−:
I K S0:mdst
I M(K0S → π+π−) ∈ [0.48, 0.52] GeV;
� B0 → η′(→ η3ππ+π−)K0
S+−
I Mbc > 5.25 GeV;
I |∆E | < 0.15 GeV;
I P-valuevtx (B0, η′,K 0
S ) > 1 · 10−5
if Ncands > 1, select candidate with highest P-valuevtx (B0, η′, η,K 0
S )
S.Lacaprara (INFN Padova) B0 → η
′K
0S B2GM 21/06/2016 6 / 17
Selection breakdonw
1.000
0.572
0.464
0.398
0.265
0.1870.170 0.164 0.164 0.163 0.162 0.161 0.158 0.151
0.121
0.030
InputSkim Reco bc
M E∆ ηM
'ηM
0πM
K_SM
/K)πLogL(
∆0
d0
z N Hits vtxP TRUE
SXF0
0.2
0.4
0.6
0.8
1
Events statistics
Selections MC true /SXF
)-π+π(S
0) K-π+π π3
η'( η→0BEvents statistics
Combinatorics
Cands mult.: 21.5Good cands mult.: 1.45
Efficiency %skim 57.2preselection 46.2good cands 15.1MC true 12.1SXF 3.0
Reco eff is as good as ηγγ channel.
50% eff drop due to poor resolution on Mbc , ∆E , Mη all coming from π0 reconstruction
in η → π+π−π0 decay
S.Lacaprara (INFN Padova) B0 → η
′K
0S B2GM 21/06/2016 7 / 17
Signal distribution B0 → η′(→ η3ππ+π−)K0
S+−
bcM5.25 5.255 5.26 5.265 5.27 5.275 5.28 5.285 5.291
10
210
310
410
510
Mbc
All cands
MC match
Good cands
" MC match
Mbc
E∆0.2− 0.15− 0.1− 0.05− 0 0.05 0.1 0.15 0.21
10
210
310
410
510
ηM0.4 0.45 0.5 0.55 0.6 0.65 0.71
10
210
310
410
510
610
'ηM0.85 0.9 0.95 1 1.05 1.1 1.151
10
210
310
410
510
610
0πM0.08 0.1 0.12 0.14 0.16 0.18 0.21
10
210
310
410
510
610
/KπLL∆20− 10− 0 10 20 30 40 501
10
210
310
410
510
)-π+π(S
0) K-π+π π3
η'( η→0B
S.Lacaprara (INFN Padova) B0 → η
′K
0S B2GM 21/06/2016 8 / 17
Vtx reco: signal and tag sideB0 → η′(→ ηγγπ
+ π−)K0S
+−
z (signal) (cm)∆0.05− 0.04− 0.03− 0.02− 0.01− 0 0.01 0.02 0.03 0.04 0.050
100
200
300
400
500
600
700
800
900
/ ndf 2χ 93.4 / 91
Prob 0.41
norm 0.1± 15.6
C
Bias 0.000097± 0.000393
C
σ 0.00015± 0.00371
T
Bias 0.000216± 0.000459
T
σ 0.00054± 0.00924
O
Bias 0.00056± 0.00166
O
σ 0.0013± 0.0269
Cf 0.03± 0.33
Tf 0.022± 0.368
Fit
Core
Tail
Outlier
mµz: 127.55 ∆mµ: 8.00 zBias
z (tag) (cm)∆0.05− 0.04− 0.03− 0.02− 0.01− 0 0.01 0.02 0.03 0.04 0.050
200
400
600
800
1000
1200
1400
1600
1800
2000
/ ndf 2χ 121 / 91
Prob 0.0208
norm 0.1± 16.1
C
Bias 0.000043± 0.000524
C
σ 0.00007± 0.00235
T
Bias 0.00011± 0.00104
T
σ 0.00026± 0.00605
O
Bias 0.00052±0.00199 −
O
σ 0.0006± 0.0185
Cf 0.025± 0.497
Tf 0.021± 0.383
Fit
Core
Tail
Outlier
mµz: 56.96 ∆mµ: 4.23 zBias
)-π+π(S
0) K-π+π γγ
η'( η→0B
Standard
z (signal) (cm)∆0.05− 0.04− 0.03− 0.02− 0.01− 0 0.01 0.02 0.03 0.04 0.050
200
400
600
800
1000
1200
/ ndf 2χ 110 / 91
Prob 0.0839
norm 0.1± 15.2
C
Bias 0.000111± 0.000355
C
σ 0.000± 0.006
T
Bias 0.0001± 0.0002
T
σ 0.00011± 0.00228
O
Bias 0.00035± 0.00101
O
σ 0.0004± 0.0212
Cf 0.017± 0.472
Tf 0.013± 0.207
Fit
Core
Tail
Outlier
mµz: 101.07 ∆mµ: 5.35 zBias
z (tag) (cm)∆0.05− 0.04− 0.03− 0.02− 0.01− 0 0.01 0.02 0.03 0.04 0.050
200
400
600
800
1000
1200
1400
1600
1800
/ ndf 2χ 117 / 91
Prob 0.0348
norm 0.1± 15.5
CBias 0.00004± 0.00052
C
σ 0.00007± 0.00233
T
Bias 0.00011± 0.00104
Tσ 0.00025± 0.00604
OBias 0.00054±0.00211 −
O
σ 0.0006± 0.0186
Cf 0.02± 0.49
Tf 0.02± 0.39
Fit
Core
Tail
Outlier
mµz: 57.22 ∆mµ: 4.09 zBias
)-π+π(S
0) K-π+π γγ
η'( η→0B
WithK0S
z (signal) (cm)∆0.05− 0.04− 0.03− 0.02− 0.01− 0 0.01 0.02 0.03 0.04 0.050
10000
20000
30000
40000
50000
60000
70000
80000
/ ndf 2χ 940 / 91
Prob 0
norm 0.8± 609
C
Bias 0.000017± 0.000435
C
σ 0.00004± 0.00534
T
Bias 0.000006± 0.000233
T
σ 0.0000± 0.0024
O
Bias 0.000± 0.005
O
σ 0.0001± 0.0156
Cf 0.005± 0.357
Tf 0.005± 0.583
Fit
Core
Tail
Outlier
mµz: 42.44 ∆mµ: 5.93 zBias
z (tag) (cm)∆0.05− 0.04− 0.03− 0.02− 0.01− 0 0.01 0.02 0.03 0.04 0.050
10000
20000
30000
40000
50000
60000
70000
/ ndf 2χ 1.02e+03 / 91
Prob 0
norm 0.8± 608
C
Bias 0.000007± 0.000498
C
σ 0.00001± 0.00245
T
Bias 0.00002± 0.00103
T
σ 0.00005± 0.00625
O
Bias 0.00008±0.00122 −
O
σ 0.0001± 0.0179
Cf 0.004± 0.527
Tf 0.003± 0.356
Fit
Core
Tail
Outlier
mµz: 56.17 ∆mµ: 4.88 zBias
)-π+π(S
0) K-π+π γγ
η'( η→0B
WithBS &
K0S
S.Lacaprara (INFN Padova) B0 → η
′K
0S B2GM 21/06/2016 9 / 17
Vtx reco: signal and tag sideB0 → η′(→ η3ππ
+π−)K0S
+−
z (signal) (cm)∆0.05− 0.04− 0.03− 0.02− 0.01− 0 0.01 0.02 0.03 0.04 0.050
5000
10000
15000
20000
25000
/ ndf 2χ 774 / 91
Prob 0
norm 0.6± 318
C
Bias 0.000025± 0.000762
C
σ 0.000± 0.006
T
Bias 0.000016± 0.000333
T
σ 0.00002± 0.00242
O
Bias 0.00008± 0.00432
O
σ 0.0001± 0.0174
Cf 0.004± 0.465
Tf 0.003± 0.296
Fit
Core
Tail
Outlier
mµz: 76.55 ∆mµ: 14.81 zBias
z (tag) (cm)∆0.05− 0.04− 0.03− 0.02− 0.01− 0 0.01 0.02 0.03 0.04 0.050
5000
10000
15000
20000
25000
30000
35000
/ ndf 2χ 674 / 91
Prob 0
norm 0.6± 319
C
Bias 0.000010± 0.000499
C
σ 0.00002± 0.00245
T
Bias 0.000027± 0.000983
T
σ 0.00007± 0.00616
O
Bias 0.00011±0.00148 −
O
σ 0.0001± 0.0179
Cf 0.006± 0.511
Tf 0.005± 0.369
Fit
Core
Tail
Outlier
mµz: 56.71 ∆mµ: 4.41 zBias
)-π+π(S
0) K-π+π π3
η'( η→0B
Stan
dard
z (signal) (cm)∆0.05− 0.04− 0.03− 0.02− 0.01− 0 0.01 0.02 0.03 0.04 0.050
5000
10000
15000
20000
25000
30000
35000
40000
45000
/ ndf 2χ 1.34e+04 / 91
Prob 0
norm 0.5± 301
C
Bias 0.00004± 0.00112
C
σ 0.00006± 0.00435
T
Bias 0.000007± 0.000199
T
σ 0.00001± 0.00205
O
Bias 0.000± 0.005
O
σ 0.0001± 0.0142
Cf 0.008± 0.285
Tf 0.009± 0.624
Fit
Core
Tail
Outlier
mµz: 38.10 ∆mµ: 8.98 zBias
z (tag) (cm)∆0.05− 0.04− 0.03− 0.02− 0.01− 0 0.01 0.02 0.03 0.04 0.050
5000
10000
15000
20000
25000
30000
35000
/ ndf 2χ 634 / 91
Prob 0
norm 0.5± 301
C
Bias 0.000028± 0.000995
C
σ 0.00007± 0.00619
T
Bias 0.000010± 0.000496
T
σ 0.00002± 0.00246
O
Bias 0.00012±0.00148 −
O
σ 0.0002± 0.0179
Cf 0.005± 0.366
Tf 0.006± 0.515
Fit
Core
Tail
Outlier
mµz: 56.70 ∆mµ: 4.43 zBias
)-π+π(S
0) K-π+π π3
η'( η→0B
With
BS
&K
0S
S.Lacaprara (INFN Padova) B0 → η
′K
0S B2GM 21/06/2016 10 / 17
Background distributionAll candidates
5.25 5.255 5.26 5.265 5.27 5.275 5.28 5.285 5.29
1000
2000
3000
4000
5000
6000
bcM
mixedcharged
uuddss
cc
0.2− 0.15− 0.1− 0.05− 0 0.05 0.1 0.15 0.2
2000
4000
6000
8000
10000
12000
14000
E∆0.4 0.45 0.5 0.55 0.6 0.65 0.7
2000
4000
6000
8000
10000
12000
14000
16000
18000
ηM
0.85 0.9 0.95 1 1.05 1.1 1.15
5000
10000
15000
20000
25000
30000
'ηM0.45 0.46 0.47 0.48 0.49 0.5 0.51 0.52 0.53 0.54 0.55
10000
20000
30000
40000
50000
60000
70000
80000
90000
S0KM
20− 10− 0 10 20 30 40 50
1
10
210
310
410
/KπLL∆
)-π+π(S
0) K-π+π) γγ(η'( η→0B
S.Lacaprara (INFN Padova) B0 → η
′K
0S B2GM 21/06/2016 11 / 17
Background distributionAll candidates
5.25 5.255 5.26 5.265 5.27 5.275 5.28 5.285 5.29
10000
20000
30000
40000
50000
bcM
mixedcharged
uuddsscc
0.2− 0.15− 0.1− 0.05− 0 0.05 0.1 0.15 0.2
20
40
60
80
100
120
140
310×
E∆0.4 0.45 0.5 0.55 0.6 0.65 0.7
50
100
150
200
250
300
350
400
450
310×
ηM
0.85 0.9 0.95 1 1.05 1.1 1.15
100
200
300
400
500
600
310×
'ηM0.08 0.1 0.12 0.14 0.16 0.18 0.2
100
200
300
400
500
310×
0πM0.45 0.46 0.47 0.48 0.49 0.5 0.51 0.52 0.53 0.54 0.55
200
400
600
800
1000
1200
1400
1600
1800
2000
2200
2400
310×
S0K
M
)-π+π(S
0) K-π+π) 0π-π+π(η'( η→0B
S.Lacaprara (INFN Padova) B0 → η
′K
0S B2GM 21/06/2016 12 / 17
Continuum Suppression correlation matrix
100−
80−
60−
40−
20−
0
20
40
60
80
100
B0_ThrustB
B0_ThrustO
B0_CosTBTO
B0_CosTBz
B0_R2B0_cc1
B0_cc2B0_cc3
B0_cc4B0_cc5
B0_cc6B0_cc7
B0_cc8B0_cc9
B0_mm2B0_et
B0_hso00
B0_hso02
B0_hso04
B0_hso10
B0_hso12
B0_hso14
B0_hso20
B0_hso22
B0_hso24
B0_hoo0B0_hoo1
B0_hoo2B0_hoo3
B0_hoo4
B0_ThrustBB0_ThrustO
B0_CosTBTOB0_CosTBz
B0_R2B0_cc1B0_cc2B0_cc3B0_cc4B0_cc5B0_cc6B0_cc7B0_cc8B0_cc9
B0_mm2B0_et
B0_hso00B0_hso02B0_hso04B0_hso10B0_hso12B0_hso14B0_hso20B0_hso22B0_hso24B0_hoo0B0_hoo1B0_hoo2B0_hoo3B0_hoo4
Correlation Matrix (signal)
100 2 2 1 3 3119 7 2 2 1 2 1 1 2 1 2 1 2100 17 3 65 12 16 14 9 1102025 5 8 3 32 4 5 27 5 12 9 4 4 1 54 2 20 2 17100 8 61 8 24 30 25 15 183746 8 14 7 52 6 16 63 17 12 29 12 11 1 15 2 4 1 3 8100 4 2 1 9 910 8 3 5 8 742 1 3 71213 6 9 311 5 1 3 65 61 4100 9 20 24 16 216344854 101422 61 13 52 20 1 26 1417 33 1 16 31 8 2 910059 9 3 5 2 6 7 6 11 18 1 5 3 6 1 4 219 12 24 1 2059100 7 1 1 2 4 5 414 18 2 14 11 21 36 37 16 18 11 20 1 18 8 7 16 30 9 24 9 7100 3 3 5 7 822 31 4 22 6 31 44 15 24 20 6 30 25 9 2 14 25 9 16 1 3100 1 1 4101118 34 8 22 7 31 3219 18 6 2 30 1 21 2 1 2 9 1510 2 1 1100 2101219 32 13 1625 28 1730 16 3 30 2 17 2 1 1 816 2 3 1 100 4 5 617 26 16 127 22 24 12 5 5 25 7 2 2
1018 334 4 5 4 2 4100 14 22 142011 211311 11 9 6 23 1 3 22037 548 5 71010 5 100 712 16 1636 12 1724 8 911 6 20 1 42546 854 4 81112 6 710014 15 1643 29 1627 19 1010 5 21 6 1 1 5 8 7 10 314221819171412141005524 55321388411379 164 235
2 8 144214 5 18 31 34 32 26 22 16 1555100 31 4 1 83 47 9 51 11 1 86 1 41 1 8 1 3 7 122 2 2 4 8 13 16 14 16 1624 31100 5 5 6 2 2 2 2 1 29 5 7 5 1 32 52 3 61 6 14 22 22 16 1203643 4 5100 7 2 16 2 2 5 3 2 20 3 2 4 6 7 7 11 6 7252711 12 29 1 5 7100 1 2 3 1 1 1 1 5 1 5 161213 6 21 31 31 28 22 21 17 1655 83 6 2 1100 52 17 58 15 1 87 1 42 11 2 27 6313 52 11 36 44 32 17 13242732 47 2 16 2 52100 42 36 43 19 46 42 1 15
5 17 6 20 18 37 1519302411 8 1913 9 2 2 3 17 42100 16 29 20 15 15 1 13 12 12 9 1 1 16 24 18 16 12 11 9 1088 51 2 2 1 58 36 16100 41 11 75 61 34 9 29 26 5 18 20 6 5 9111041 11 2 5 15 43 29 41100 44 23 45 33 4 12 3 14 3 11 6 2 3 5 6 6 513 1 1 3 1 19 20 11 44100 3 16 22 4 111117 6 20 30 30 30 25 23 20 2179 86 29 87 46 15 75 23 3100 53 2 18 1 1 1 1 1 2 1 1 1 5 2 1 1 100 28 2
1 54 15 5 33 4 18 25 21 17 7 1 4 664 41 7 20 1 42 42 15 61 45 16 53 100 1 54 2 2 1 2 2 2 3 1 2 1 5 1 1 1 2 28 1100 1 20 4 1 16 2 8 9 1 2 2 135 8 3 5 11 15 13 34 33 22 18 2 54 1100
Linear correlation coefficients in %
100−
80−
60−
40−
20−
0
20
40
60
80
100
B0_ThrustB
B0_ThrustO
B0_CosTBTO
B0_CosTBz
B0_R2B0_cc1
B0_cc2B0_cc3
B0_cc4B0_cc5
B0_cc6B0_cc7
B0_cc8B0_cc9
B0_mm2B0_et
B0_hso00
B0_hso02
B0_hso04
B0_hso10
B0_hso12
B0_hso14
B0_hso20
B0_hso22
B0_hso24
B0_hoo0B0_hoo1
B0_hoo2B0_hoo3
B0_hoo4
B0_ThrustBB0_ThrustO
B0_CosTBTOB0_CosTBz
B0_R2B0_cc1B0_cc2B0_cc3B0_cc4B0_cc5B0_cc6B0_cc7B0_cc8B0_cc9
B0_mm2B0_et
B0_hso00B0_hso02B0_hso04B0_hso10B0_hso12B0_hso14B0_hso20B0_hso22B0_hso24B0_hoo0B0_hoo1B0_hoo2B0_hoo3B0_hoo4
Correlation Matrix (background)
100 2 3 8 10 381816 5 5 2 4 8 2 3 1 5 4 2 4 2 4 4 2 4 3 2 2100 41 88 9 26 22 13 325344649 4 5 8 45 25 10 53 30 8 21 14 5 51 3 32 3 41100 6 49 6 18 20 8 115263443 1 3 1 33 20 4 41 18 19 9 1 5 19 5 12 8 6100 9 10 4171713 5 8 863 2 1 42919 612 4 523 3 7 6 3 10 88 49 9100 19 21 13 32139454951 112121 41 3414 44 39 9 21 1720 2 36 2 33 38 9 6 10 19100571313 3 5 3 1 6 6 14 19 3 6 21 2 3 2 1 5 6 4 918 26 18 4 2157100 6 1 2 3 6 6 619 22 6 22 22 25 36 33 18 20 18 25 1 33 2 2516 22 2017 1313 6100 8 4 3 4 9 422 37 7 12 5 36 46 17 23 11 5 34 1 31 2 9 5 13 817 313 1 8100 511 1 2 515 36 8 1113 34 2221 18 3 6 31 21 2
3 11321 2 4 5100 1 1 1 20 30 13 419 30 726 18 3 5 32 2 10 5 52515 539 3 3 311 1100 2 11 418 17 19 713 151220 15 6 8 23 3 5 13
3426 845 5 6 4 1 1 2100 5 714 19 121917 161412 13 7 3 20 9 5 8 24634 49 6 9 2 1 11 5100 8 6 13 1423 8 1318 613 9 16 116 211
4943 51 3 6 4 5 4 7 810011 13 1718 1 927 3 8 8 6 16 515 1 8 4 4 1 8 11 1192215201814 611100473419 548341587583479 572 546 8 5 36321 6 22 37 36 30 17 19 13 1347100 29 17 1 80 53 10 48 7 81 44 4 9 2 8 1 221 6 6 7 8 13 19 12 14 1734 29100 55 23 812 5 13 2 3510 14 8 2 3 45 33 1 41 14 22 12 11 4 719231819 17 55100 64 4 4 8 8 7 2013 35 7 20 1 25 20 4 34 19 22 513191317 8 1 5 1 23 64100 7 2 3 3 310 18 4 21 5 10 42914 3 25 36 34 30 15 16 13 948 80 8 4 7100 69 21 55 14 5 83 3 50 1 15 4 53 4119 44 6 36 46 22 71214182734 5312 4 2 69100 57 38 33 21 55 4 63 2 34 2 30 18 6 39 21 33 1721262012 315 10 5 21 57100 13 30 28 17 37 2 36 4 8 12 9 2 18 23 18 18 15 13 6 887 48 13 8 55 38 13100 60 33 77 70 45 2 21 19 4 21 3 20 11 3 3 6 713 858 7 2 8 3 14 33 30 60100 62 31 2 69 3 58 4 14 9 5 17 2 18 5 6 5 8 3 9 634 7 3 5 21 28 33 62100 15 4 42 49 4 5 12320 1 25 34 31 32 23 20 16 1679 81 35 20 3 83 55 17 77 31 15100 2 65 3 27 2 5 3 2 5 1 1 2 3 1 5 5 101310 3 4 2 4 2100 38 3 4 51 19 7 36 6 33 31 21 10 5 9161572 44 14 35 18 50 63 37 70 69 42 65 100 5 69 3 3 5 6 2 4 2 2 2 5 2 1 5 4 8 7 4 1 2 2 3 3 38 5100 1 2 32 12 3 33 9 25 9 513 811 846 9 2 20 21 15 34 36 45 58 49 27 3 69 1100
Linear correlation coefficients in %
S.Lacaprara (INFN Padova) B0 → η
′K
0S B2GM 21/06/2016 13 / 17
Toy results B0 → η′(→ ηγγπ+ π−)K0
S+−
Tight CS
Tight: εsig ,sxf ,peaking = 50%, εcontinuum = 2.5%
Nsig = 195, Nsxf = 8, Ncont = 83, Npeak = 15
0.2− 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.60
10
20
30
40
50
60
70
Toy results - dtSig_S Entries 1000
Mean 0.0079± 0.703
Std Dev 0.00559± 0.25
Toy results - dtSig_S
0.6− 0.4− 0.2− 0 0.2 0.4 0.60
10
20
30
40
50
60
70
80
Toy results - dtSig_C Entries 1000
Mean 0.00539± 0.0103
Std Dev 0.00381± 0.17
Toy results - dtSig_C
0 50 100 150 200 250 300 350 4000
20
40
60
80
100
120
140
Toy results - nSig Entries 1000
Mean 0.403± 195
Std Dev 0.285± 12.7
Toy results - nSig
Par Bias RMS
S (0.7) 0.703± 0.008 0.25C (0.0) 0.010± 0.005 0.17nSig 195.4± 0.4 12.7
S.Lacaprara (INFN Padova) B0 → η
′K
0S B2GM 21/06/2016 14 / 17
Toy results B0 → η′(→ ηγγπ+ π−)K0
S+−
Loose CS
Loose: εsig ,sxf ,peaking = 95%, εcontinuum = 42%
Nsig = 390, Nsxf = 14, Ncont = 1400, Npeak = 28
0.2− 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.60
10
20
30
40
50
60
70
80
Toy results - dtSig_S Entries 1000
Mean 0.00572± 0.703
Std Dev 0.00405± 0.181
Toy results - dtSig_S
0.6− 0.4− 0.2− 0 0.2 0.4 0.60
10
20
30
40
50
60
70
80
90
Toy results - dtSig_C Entries 1000
Mean 0.00441± 0.00198
Std Dev 0.00312± 0.139
Toy results - dtSig_C
0 100 200 300 400 500 600 700 8000
20
40
60
80
100
120
Toy results - nSig Entries 1000
Mean 0.804± 390
Std Dev 0.568± 25.4
Toy results - nSig
Par Bias RMS
S (0.7) 0.703± 0.005 0.18C (0.0) 0.002± 0.004 0.14nSig 389.8± 0.8 25.4
S.Lacaprara (INFN Padova) B0 → η
′K
0S B2GM 21/06/2016 15 / 17
Comparison with Belle/BaBar
This analysis? Belle[Belle(2014)] BaBar[BABAR(2009)]
mode (340 M B B) (772 M B B) (467 M B B)
η′ → π±η Nsig σS σC Nsig σS σC Nsig σC σS
ηγγK0S
+−390 0.19 0.11 648 0.15 0.098 472 0.17 0.11
ηγγK0S
00Just started 104 0.21† 0.18† 105 0.34 0.30
η3πK0S
+−106 0.33 0.25 174 0.26 0.18 171 0.26 0.20
η3πK0S
00Will try Not used
η′ → ρ0γK0S
+−Not yet 1411 0.098 0.069 1005 0.12 0.09
η′ → ρ0γK0S
00Not yet 162 0.21† 0.18† 206 0.33 0.26
?Very preliminary estimate based on toy MC, L = 300 fb−1
Warning: no machine background yet†Results combining η′ → π±ηγγ and η′ → ρ0γ
S.Lacaprara (INFN Padova) B0 → η
′K
0S B2GM 21/06/2016 16 / 17
Bibliography I
[Williamson and Zupan(2006)] Alexander R. Williamson and Jure Zupan. Two body b decays with isosinglet final states in softcollinear effective theory. Phys. Rev. D, 74:014003, Jul 2006. doi: 10.1103/PhysRevD.74.014003. URLhttp://link.aps.org/doi/10.1103/PhysRevD.74.014003.
[Gronau et al.(2006)] Michael Gronau et al. Updated bounds on cp asymmetries in B0 → η
′KS and B
0 → π0
KS . Phys.Rev. D, 74:093003, Nov 2006. doi: 10.1103/PhysRevD.74.093003. URLhttp://link.aps.org/doi/10.1103/PhysRevD.74.093003.
[Belle(2014)] Belle. Measurement of time-dependent cp violation in b0 → η′k0 decays. Journal of High Energy Physics, 2014
(10):165, 2014. doi: 10.1007/JHEP10(2014)165. URL http://dx.doi.org/10.1007/JHEP10%282014%29165.
[Urquijo(2015)] Phillip Urquijo. Comparison between belle ii and lhcb physics projections. Technical ReportBELLE2-NOTE-PH-2015-004, Apr 2015.
[CLEO(1998)] CLEO. Observation of high momentum η′
production in B decays. PRL, 81:1786, 1998. doi:10.1103/PhysRevLett.81.1786. URL http://link.aps.org/doi/10.1103/PhysRevLett.81.1786.
[BABAR(2009)] BABAR. Measurement of time dependent cp asymmetry parameters in B0
meson decays to ωK0S , η′
K0
, and
π0
K0S . PRD, 79:052003, 2009. doi: 10.1103/PhysRevD.79.052003. URL
http://link.aps.org/doi/10.1103/PhysRevD.79.052003.
[Belle(2007)] Belle. Observation of time-dependent cp violation in B0 → η
′K
0decays and improved measurements of cp
asymmetries in B0 → ϕK
0, K
0S K
0S K
0S and B
0 → j/ψK0
decays. PRL, 98:031802, 2007. doi:10.1103/PhysRevLett.98.031802. URL http://link.aps.org/doi/10.1103/PhysRevLett.98.031802.
S.Lacaprara (INFN Padova) B0 → η
′K
0S B2GM 21/06/2016 17 / 17