Measurements at B-factories
-1
with a luminosity of 2ab
Ryosuke Itoh
KEK (Belle Collaboration)
LHCb Upgrade Workshop
Edinburgh, Jan. 11-12, 2007
R.Itoh@LHCB upgrade WS
1
Outline
1. Introduction to B-factory experiments
2. Measurements with 2ab-1 data
- UT angles
- UT sides
- Rare decays
3. Impacts on Physics
4. Good-bye, B-factories. Hello, Super B-factory!
5. Summary
R.Itoh@LHCB upgrade WS
2
1. Introduction to B-factory experiments
PEP-II at SLAC
9GeV (e)  3.1GeV (e+)
peak luminosity:
13 countries,
57 institutes,
~400 collaborators
1.121034cm2s1
Belle
BaBar
KEKB at KEK
11 nations,
80 institutes,
623 persons
Shutdown in 2008
R.Itoh@LHCB upgrade WS
8GeV (e)  3.5GeV (e+)
peak luminosity:
1.711034cm2s1
world record
Running plan after 1ab-1 is still unclear
3
KEKB/Belle (as of Dec.06)
KEKB + PEP-II
Lpeak > 1.711034cm-2s-1
Ltot >700 fb-1 !!!
Belle+Babar > 1ab-1
by now!!!!
KEKB
for Belle
PEP-II
for BaBar
WG4 experiment summary
-1
Results with 2ab (Belle+BaBar)
will appear in HFAG2009!
R.Itoh@LHCB upgrade WS
4
2. Measurements with 2ab-1 data
1) sin2f1(sin2b)
Measurements today are with:
Belle : 0.49ab-1
BaBar: 0.35ab-1
sin2f1/b(bc) = 0.674±0.026
sin2f1/b(bs) = 0.58±0.13
R.Itoh@LHCB upgrade WS
5
Estimated error for 2ab-1
ー Total error
ー Statistical error
Y.Nakahama@CKM2006
ー Systematic
-1
Stat
Sys
L(ab
) Total
error
535MBB 5/ab
↑0.492/ab
50/ab 0.492
5
50
0.035
0.017
0.014
0.031
0.010
0.003
0.017
0.014
0.013
L /ab
Ldt(ab-1) dsin2f1(bc) dsin2f1(bs)
0.026 (3.9%)
0.13 (22%)
0.84
2
0.020 (2.9%)
0.09 (16%)
* Systematic error becomes dominant in sin2f1(bc).
* Vertexing error is the dominant systematics.
R.Itoh@LHCB upgrade WS
6
2) f2/a
3 modes are used:
a) B0p+p
- time-dependent CPV
+ isospin analysis
b) B0r+r
- time-dep. angular anal.
+ isospin analysis
c) B0rp
- time-dependent Dalitz
(+ isospin analysis)
f2/a = [93 +11
 9 ]
R.Itoh@LHCB upgrade WS
7
* A prediction of measurement errors with 2ab-1 data is difficult
- results are obtained by combining three different analyses,
- each of analysis depends on many measurement results.
(isospin analysis requires measurements of multiple Br's.)
* Still statistical error is expected to dominate with 2ab-1 data.
ex. errors in current p+p analysis
App  +0.55  0.08  0.05
Spp  0.61  0.10  0.04
App  +0.16  0.11  0.03
Spp  0.53  0.14  0.02
Belle
BaBar
error is scaled by the luminosity
Ldt(ab-1)
0.84
2
R.Itoh@LHCB upgrade WS
df2
s
o
10 (11%)
6o (7%)
8
Trabelsi@CKM2006
3) f3/g
BD(*)K(*)
Methods:
1) GLW
2) ADS
3) GGSZ (Dalitz)
f3/g = [77±31]
Dominant meas.
by GGSZ method
BaBar
R.Itoh@LHCB upgrade WS
Belle
9
* The sensitivity strongly depends on the value of rB
* BaBar measurement does not give finite rB values for now.
Optimistic assumption for 2ab-1 prediction:
Take Belle measurement and scale the error by luminosity.
Ldt(ab )
0.35
-1
2
df3
17o (11%)
12o (7%)
Systematic and model errors are assumed to be unchanged.
R.Itoh@LHCB upgrade WS
10
4) Vub
* Current best measurement is given by the inclusive measurement.
* Exclusive measurement : Bpln
- large uncertainty from LQCD calculations of FF
Inclusive
Bpln
Inclusive (DGE):
(4.46±0.20±0.20)10-3 : Stat. err. is already comparable with theo. err.
R.Itoh@LHCB upgrade WS
11
LLR method (BaBar)
Less model dependent
by using the measured photon energy spectrum in BXsg
Ldt(ab-1)
0.45
2
R.Itoh@LHCB upgrade WS
dVub
A.Limosani@BNM2006
6.3% (DGE)
4.9% (LLR)
12
5) B(r,w)g
SM
g
W
Vtd,Vts
b
NP
%

ss,d b
g
ss,d
% c%, t%
u,
u, c,t
* Sensitive to NP
* Alternative measurement of |Vtd/Vts|
Belle: 370 fb-1
Mbc(GeV/c2)
R.Itoh@LHCB upgrade WS
E(GeV)

BaBar: 316 fb-1
 → r+ g
13
Belle
Mode
B +  r +g
B0  r 0g
B0  wg
N signal
8.5
20.7
5.7
B  r /wg
36.9
BaBar
Significance BF(106 )
+0.09
1.6
0.55+0.42
0.36 0.08
+0.07
5.2
1.25 +0.37
0.33 0.06
+0.05
2.3
0.56+0.34
0.27 0.10
5.1
+ 0.10
1.32 +0.34
0.31 0.09
Mode
Nsignal
Significance
BF(106 )
B+  r + g
42.0 +14.0
12.7
3.8
1.10 +0.37
0.33  0.09
B0  r 0 g
38.7 +10.6
9.8
4.9
0.79 +0.22
0.20  0.06
B 0  wg
11.0 +6.7
5.6
2.2
0.40 +0.24
0.20  0.05
Combined BF
6.4
1.25 +0.25
0.24  0.09
Ldt(ab ) dBr((r,w)g)
16.3%
0.69
-1
2
10.3%
Note: theoretically controversial on the inclusion of w
(w is not a member of iso-triplet.)
R.Itoh@LHCB upgrade WS
14
6) Btn
SM
NP
mb tan b + mu cot b
mt tan b
b
u
H+/W+
t+
Br = BrSM x rH
* Another Vub measurement
* Seinsitive to NP(charged Higgs)
447 10 B pairs
hadronic tag
6
SM : B(tn) = (1.59  0.40)×10-4
17.2+5.3
4.7
(3.5)
Ldt(ab-1) dBr(tn)
36%
0.41
2
R.Itoh@LHCB upgrade WS
27%
15
Constraints on H+ mass
0.41ab-1
rH
2
tan b / mH
95.5%C.L. exclusion boundaries
5ab-1
fB(LQCD) = 5%
R.Itoh@LHCB upgrade WS
rH
2
16
7) AFB(BK*ll)
* Sensitive to NP thru. determination of Wilson Coeff (C7,C9 and C10)
Belle
BaBar
Ldt(ab-1)
0.36
2
AFB=0.56±0.13
R.Itoh@LHCB upgrade WS
dAFB
23%
10%
AFB>0.19@95%CL
17
Summary of measurement errors with 2ab-1 data
Today
2ab-1
sin2f1/b(bc)
0.026
0.020
sin2f1/b(bs)
0.13
0.09
11o
6o
19o
6.3%
12o
4.9%
0.8%
20.4%
36%
0.8%
10.3%
27%
23%
10%
f2
f3
Vub(inclusive)
md
B(B(r,w)g)
B(Btn)
AFB(K*l+l-)
R.Itoh@LHCB upgrade WS
18
A.Stocchi@Frascati SuperB WS
R.Itoh@LHCB upgrade WS
19
3. Impact on Physics
a) Constraints on Standard Model by CKM fit.
1. Experimental measurements
a) B-factory measurements
Vub, sin2f1(bc), f2, f3, md, Br(Btn), Br(r/wg)/Br(K*g)
b) Tevatron/LHC(b) measurements
ms - LHCb expectation for 2ab-1 fits (dms~0.06%)
- possibility to include other measurements (ex. f3), but not taken in the fits
c) Kaon sector measurements
eK - current best value is used in all fits (deK
~3.6%)
2. Theoretical inputs
Decay constants, etc.: mostly relies on LQCD calculations
 2006 calculations are used in all fits
* Central values : HFAG averages (2006 summer) except f3/g (Belle)
* Fit engine : CKMfitter “range fit treatment” for sys/theo errors
R.Itoh@LHCB upgrade WS
20
CKM fit
as of today
d(r,h) =
(15.8%,5.6%)
Prediction
with 2ab-1 data
d(r,h) =
(10.0%,4.4%)
R.Itoh@LHCB upgrade WS
21
b) Model-independent NP search
Comparison between
- tree level measurements : |Vub| and f3, and
Today
d(r,h) =(45%,28%)
2ab-1
d(r,h) =(31%,20%)
- measurements sensitive to NP :
sin2f1(bc) and md  NP in B0-B0 mixing
NP modeling: Expansion of mixing amplitude
M = rd2 MSMexp(-i2qd)
NP scale
R.Itoh@LHCB upgrade WS
NP phase
22
2ab-1
today
2ab-1
rd2
1-CL
1-CL
Today
2qd
(rad)
2
d
r =
+1.20
1.29
(today)
-0.62
+0.78
1.18
(2ab-1)
-0.46
R.Itoh@LHCB upgrade WS
+0.26
2qd = -0.08
-0.11
+0.08
-0.10
-0.08
(today)[~11o]
(2ab-1)[~5o]
23
4. Good-bye, B-factories. Hello, Super B-factory!
The upgrade of current KEKB accelerator to SuperKEKB is
being planned for the further studies of B and other flavor physics.
Interaction Region
SuperKEKB
Crab crossing
 =30mrad.
q
by*=3mm
New QCS
New Beam pipe
8GeV (e+, 4.1A)
3.5GeV (e-, 9.6A)
More RF power
Increase beam currents
•1.75 A (LER) / 1.36 A (HER)
→ 9.6 A (LER) / 4.1 A (HER)
Smaller by*
• 6 mm→3 mm
Increase y
• 0.059→>0.24(W-S)
R.Itoh@LHCB upgrade WS
Damping ring
Linac upgrade
L > 8x1035cm-2s-1
24
KEKB Upgrade Scenario
Lpeak > 1.71034cm-2s-1
Ltot >700 fb-1 !!!
world records !
Major upgrade of
KEKB & Belle detector
(>1yr shutdown)
Lpeak (cm-2s-1)
Lint
1.7x1034
700 fb-1
3x1034
~2 ab-1
8x1035
~50 ab-1
-1
~ 50ab in late 2010's
R.Itoh@LHCB upgrade WS
25
RI@CKM2006
SuperKEKB
(5 ab-1)
SuperKEKB
(50 ab-1)
d(r,h)
~ O(1) %
with very
conservative
assumptions
R.Itoh@LHCB upgrade WS
26
Physics Reach at SuperKEKB
50ab-1
CKM
w/ n
FCNC
CPV (bs)
5ab-1
+ rich t physics
R.Itoh@LHCB upgrade WS
Physics at Super B Factory (hep-ex/0406071)
27
5. Summary
* Measurements at B-factories with 2ab-1:
- are still expected to improve with the statistics,
- syst./theo. errors become dominant in some measurements
(Vub, sin2f1/b.....).
* Impact on Physics with 2ab-1:
- ~10% determination of rh apex in Unitarity Triangle.
- Sensitivity to NP by comparing (f3/g,Vub) and (sin2f1/b,md)
d(NP scale) > 50%  limited by uncertainties in theories,
d(NP phase) ~ 5o.
* B-factories will pass the baton of “B-physics frontier”
to LHCb soon, but half of it will be passed to Super B-factory!
* Further SM constraint and NP search in B decays:
- The lattice QCD calculation is another important player.
R.Itoh@LHCB upgrade WS
28
Backup Slides
R.Itoh@LHCB upgrade WS
29
Measurement Technique at B-factories
- B0and B0 mesons are produced from U(4S) decay at B-factories.
- To measure A(t), we need to know decay time difference (t)
of two B0 mesons with the flavor of one tagged.
l-
Asymmetric collision
-
e (8.0GeV)
U(S)
B0
+
e (3.5GeV)
J/
KS
B0
charge
flavor
R.Itoh@LHCB upgrade WS
lepton
kaon
etc.
 z~c  t
30
r+r: Smaller contribution
than that in Bp+p
(Br(Br0r0) ~ 0 )
Measurement of f2 using Bp+p,r+r
b
Bd0
d
Vtb
t Vtd
W
W
Vtd t Vtb
Vud
W
d
Bd0
b
·(
b
u
d
u
+
Vub*
Tree
d
d
b
t
d
u
Vub*
Penguin
g
Vud
d
u
d
)
−
tt//
−

indirect CPV
direct CPV
ee ∣∣ ∣∣
P
P t
t =
=
[1q⋅{S
[1q⋅{S  sin m  t }Acos
cosm
m
tt]]
44
BB
BB
feff
dd: :strong
phase
diff.
strong
phase
diff.
22
qq: :determind
== 1−A
S  =
=
1−A sin
sin2
2
determindfrom
from
2 
2 
22
1
1
 
Isospin Analysis
Analysis
Isospin
2
*
*
i 

3
i



2
∣
3
  ∣−1
V−2itbV1
V
V
∣
∣
1
P
/T

e
−2i

  ∣−1A =
td ∣P
ud/T ub
∣
∣

e
2
≡−C  
2
2
+ =e
⋅
=e
-=
A
=
≡−C

   ∣1

*
* i − 
i −
2
∣
3
3


1
V tb V1
V ub∣e
1∣P /T ∣∣e   ∣
d
td ∣V
Pud/T
22ℑ
ℑ


∣∣ ∣∣
R.Itoh@LHCB upgrade WS
31
Isospin Analysis
Penguin contribution to B0p+p
f2 measured from CP asymmetry in Bp+p is shifted by q.
S   = 1−A
2

sin 22
Need to measure q
1
2
A B 0  + - 
2q
Isospin Analysis (Gronau et al.)
1 % 0
A  B  +  - 
0
0 0
%
A

B


2
0
0
0
A B    
2i
%
A =e
A
3
%A  B -  - 0 = A B +  + 0 
R.Itoh@LHCB upgrade WS
32
Measurement of f2 using Brp
S.T'Jampens@BEAUTY06
Dominant mode ρ+p – is not a CP eigenstate
t 0
t
Aleksan et al, NP B361, 141 (1991)
r0p0
B
Amplitude interference in Dalitz plot
r+p–
r–p+
simultaneous fit of a and strong phases
Measure 26 (27) bilinear Form Factor coefficients
q/ p
~ e 2i b
mixing
Snyder-Quinn, PRD 48, 2139 (1993)
B
A +
+ 
+ r p
A
0
0
CP
0 0
A00
r
p
A00
A + r p +
A +
correlated 2 fit to determine physics quantities
(347m)
(449m)
no constraint at 2 level
[60, 95]º
at 68.3% C. L.
Dalitz analysis + isospin (pentagon) analysis
Lipkin et al., PRD 44, 1454 (1991)
R.Itoh@LHCB upgrade WS
33
History of B0→p+p− decay
(C = A)
2.3 diff.
btw. Belle
and BaBar
R.Itoh@LHCB upgrade WS
34
Measurements of f3 by Dalitz (GGSZ)
s +
K
u
b
B
Vcb
+
u
b
c
u
Vub
u 0
c D
s
D0
u
u
* Use 3 body final state identical for D0 and D0
D0(D0)  KS p+ p
K+
Dalitz Plot density: |M|2
B+:
r
B-:
r
r = amplitude ratio
d = strong phase diff.
f(m12, m22) : D0 decay model
CPV: Asymmetry in Daltz dist.: m+=m(Ksp+), m=m(Ksp)
If f is known, all of r, d, and f3 can be determined from the fit
to the Dalitz plot.
R.Itoh@LHCB upgrade WS
35
Belle:
- 386 M BB events
- Improved continuum suppression
K
*
D
B
B 
DK* 


DK
B

331±17 events
B-
R.Itoh@LHCB upgrade WS
B+
81±8 events
B-
54±8 events
B+
B-
B+
36
Nakao@CKM2006
R.Itoh@LHCB upgrade WS
37
Search for B → K(*) nn
Search for B → K nn
Belle B → K* nn
535 M BB; yield = 4.7 +31
2
1.7; BR(SM)= 1.3x10
R.Itoh@LHCB upgrade WS
38