Post on 16-Mar-2021
Results from the B factories
Steve Playfer, University of Edinburgh
Annual Theory Meeting Durham, December 19th 2005
• Rough guide to B-factories for theorists
• How the CKM unitarity triangle was measured
• The search for hints of new physics in B decays
• What happens next?
Apologies for omitting spectroscopy, τ decays, charm physics ...
BaBar/Belle have published >300 papers in last 4 years
1
KEK-B and PEP-II
8 GeV e− on 3.5 GeV e+
Peak Luminosity 1.6 × 1034
9 GeV e− on 3.1 GeV e+
Peak Luminosity 1.0 × 1034
2
The BaBar Detector
The Belle detector looks very similar!
3
Integrated Luminosities - December 2005
Belle 514fb−1
]-1
Inte
gra
ted
Lu
min
osi
ty [
fb
0
50
100
150
200
250
300
Delivered LuminosityRecorded Luminosity
Off Peak
BaBarRun 1-5
PEP II Delivered Luminosity: 316.59/fb
BaBar Recorded Luminosity: 303.97/fb
Off Peak Luminosity: 26.80/fb
BaBarRun 1-5
PEP II Delivered Luminosity: 316.59/fb
BaBar Recorded Luminosity: 303.97/fb
Off Peak Luminosity: 26.80/fb
12/08/2005 04:16
2000
2001
2002
2003
2004
2005
BaBar 317fb−1
Both experiments expect to accumulate 1ab−1 by 2008
4
CKM Sector - before and after
HFAG 2005
Many more measurements
from B decays:
Angles of triangle
α, β and γ are
measured as well
PDG 2000
Sides of triangle only:
ε from K0 system
Vtd from B0 mixing
Vub from b→ u`ν
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
-0.4 -0.2 0 0.2 0.4 0.6 0.8 1
excluded at CL > 0.95
α
∆md
εK
γ ∆ms & ∆md
|Vub/Vcb|
excluded at CL > 0.95
sin 2β
sol. w/ cos 2β < 0(excl. at CL > 0.95)
α
βγ
ρ
η
excl
uded
are
a ha
s C
L > 0.95 C K M
f i t t e rEPS 2005
5
Unitarity Triangle is overconstrained!
Constraints
on angles
α, sin 2β, γ ⇒
Constraints
on sides
|Vub
Vcb
|,∆md
⇐ ∆ms, εK
6
Why do we need asymmetric B-factories?
⇒ Coherent production of B0B0 and B+B− pairs at the Υ(4S)
⇒ Asymmetric energy boosts B mesons along beam axis
Makes time-dependent CP asymmetry measurements possible!
7
CP violation in B decays
• CP violation from mixing alone is small: | qp| 6= 1
equivalent to ε in K0 system
• Direct CP violation requires two different weak and strong
phases: | AA| 6= 1
equivalent to ε′ in K0 system
• Time dependent CP violation can occur via interference
between mixing and decay: Im(λ) = Im( qp
AA
) 6= 0
This is large in the B0 system!
8
Mixing of Neutral B mesons
Time-dependent
oscillations of
an initial Bd beam
Lifetime τd = 1.528 ± 0.009ps
|ψB0(t)|2 = g+(t)|B0 > − qpg−(t)|B0 >
|ψB0(t)|2 = g+(t)B0 > −pqg−(t)|B0 >
∆md = 0.506 ± 0.005/ps
g± = 12 (e−ωHt ± e−ωLt)
ωH,L = MH,L − i2ΓH,L
9
CP violation in mixing:
Decay rate difference:
CPT and CP violation:
|q/p| = 1.029 ± 0.013 ± 0.011
sgn(Re[λ])∆Γ/Γ = −0.008 ± 0.037 ± 0.018
(Re[λ]/|λ|) Re[z] = 0.014 ± 0.035 ± 0.034
Im[z] = 0.038 ± 0.029 ± 0.025
BaBar,
PRD 70,
012007 (2004)
10
Time Dependent CP violation
ACP (f) =Γ(B0 → f) − Γ(B0 → f)
Γ(B0 → f) + Γ(B0 → f)= S(f) sin∆mt−C(f) cos ∆mt
S =2Im[λ]
1 + |λ|2C =
1 − |λ|2
1 + |λ|2λ =
q
p
A
A
Unmixed
Mixed
arbi
trar
y sc
ale
a)
Unmixed
Mixed
b)
∆t (ps)
0
20
40
60
-5 0 5
0
20
40
60
-5 0 5
B0 tags
B− 0 tags
arbi
trar
y sc
ale
a)
B0 tags
B− 0 tags
b)
∆t (ps)
0
20
40
60
-5 0 5
0
20
40
60
-5 0 5
(a) perfect
(b) realistic
time resolution
For a single decay amplitude |λ| = 1, S =Im[λ], C=0
11
Belle: hep-ex/0507037
B0 → J/ψK0
0
100
200
300 q=+1q=−1
Ent
ries
/ 0.5
ps
-0.5
0
0.5
-7.5 -5 -2.5 0 2.5 5 7.5
-ξf∆t(ps)
Asy
mm
etry
sin 2β = 0.652 ± 0.039 ± 0.020
C = 0.010 ± 0.026 ± 0.036
BaBar PRL 94, 161803 (2005)
(Top: J/ψKS Bottom: J/ψKL)
-5 0 5
Evt
s. /
0.4
ps
200
-5 0 5
Evt
s. /
0.4
ps
200 tags0B
tags0 B
a)
-5 0 5
Raw
asy
m.
-0.5
0
0.5
-5 0 5
Raw
asy
m.
-0.5
0
0.5 b)
-5 0 5
Evt
s. /
0.4
ps
100
-5 0 5
Evt
s. /
0.4
ps
100 tags0B
tags0 B
c)
-5 0 5
Raw
asy
m.
-0.5
0
0.5
-5 0 5
Raw
asy
m.
-0.5
0
0.5 d)
sin 2β = 0.722 ± 0.040 ± 0.023
C = 0.051 ± 0.033 ± 0.014
12
0.0 50.0 100.0
PDG2004BABARBelle
CLEO
New Avg.
HFAG
JULY 15th 2005
Branching Ratio x 106
Charmless B Branching Fractions
CDF
η′K+η′K0
K+π+π−K0π+π−
a−1 π+K+π−π0
K∗0(1430)0π+
ηK+π−K+K−K+
ρ+ρ−ρ+ρ0
K+K−K0
ηK∗+ρ∓π±
K0π+K+π−
ηK∗0ηπ+π−
π+π−π+K∗+π−
ωρ+K+π0
ρ+π0
K+KSKS
K0π0
K∗0(1430)+π−
K∗+ρ0
K∗0ρ+K∗0π+
K+ρ−
φK∗0
φK∗+
ρ0π+φK+
K+f0(980)φK0
ηρ+
K∗0(1430)0π0
K∗+π0
ωπ+
ωK0
ωK+KSKSKS
π+π0K0ρ0
K+π+π−(NR)ηπ+
π+π− K+ρ0
K0f0(980)η′π+
φφK+ηK+
ρ0π0π0π0
K+K0
K0K0
0.0 10.0 20.0
13
Described by sum
of b→ u tree
bW- u
d}π
d u} π +
d
and b→ s(d) penguin
b
W-
dg
t
uu}}d
d+
π-
π
Beneke & Neubert
Nucl.Phys.B675:333-415,2003
Sensitivity to electroweak penguins: Buras et.al. hep-ph/0512059
0.0 12.5 25.0
HFAG
JULY 15th 2005
Branching Ratio x 106
B(B → Kπ, ππ, KK )
PDG2004
BABA R
Belle
CLEO
New Avg.
CDF
K0π+
K+π−
K+π0
K0π0
π+π0
π+π−
π0π0
K+K0
K+K−
K0K0
14
Direct CP violation in B → KπBelle PRL 93, 191802(2004)
ACP = −0.101 ± 0.025 ± 0.005
BaBar PRL 93, 131801 (2004)
)2
(GeV/cESm5.2 5.22 5.24 5.26 5.28 5.3
2
200
400 a)
)2
(GeV/cESm5.2 5.22 5.24 5.26 5.28 5.3
Asy
mm
etry
-0.1
0
0.1
)2
(GeV/cESm5.2 5.22 5.24 5.26 5.28 5.3
Eve
nts
/ 2.5
MeV
/cA
sym
met
ry
-0.1
0
0.1 b)
ACP = −0.133 ± 0.030 ± 0.009
15
+1.0
0.0
-1.0
CP Asymmetry in Charmless B Decays
HFAG
JULY 15th 2005
PDG2004
BABARBelle
CLEO
New Avg.
CDF
K+K
SK
K+K
−
K+
π+π−
π+
K+π−
π0
K+π
+π−
ρ+ρ
0
ρ+π
0
ρ0 π
+
K+ρ−
K∗+ρ
0
K∗0 ρ
+
K∗+π−
ωπ
+
ωK
+
φK
∗+
φK
+
φK
∗0
ηK∗0
ηρ+
ηπ+
ηK∗+
ηK+
η′ π
+
η′ K
+
π0 π
0
π+π
0
K+π
0
K0 π
+
K+π−
s``sγ
K∗ γ
Only ACP (B → K±π∓) is significant so far ...
16
α− αeff from isospin
analysis of B → ππ
Gronau & London (1990)
S(ππ) = sin(2αeff )
C(ππ) = −ACP ∝ sin δ
No penguins:
C = 0, α = αeff
Measurement BaBar Belle
BF (π+π−) × 10−6 5.5 ± 0.4 ± 0.3 4.4 ± 0.6 ± 0.3
BF (π+π0) × 10−6 5.8 ± 0.6 ± 0.4 5.0 ± 1.2 ± 0.5
BF (π0π0) × 10−6 1.2 ± 0.3 ± 0.1 2.3 ± 0.5 ± 0.3
S(π+π−) −0.30 ± 0.17 ± 0.03 −0.67 ± 0.16 ± 0.06
C(π+π−) −0.09 ± 0.15 ± 0.04 −0.56 ± 0.12 ± 0.06
C(π+π0) −0.01 ± 0.10 ± 0.02 +0.02 ± 0.08 ± 0.01
C(π0π0) +0.12 ± 0.56 ± 0.06 +0.44 ± 0.53 ± 0.17
17
α from isospin analysis of B → ρρ
There are some advantages to using ρρ:
• BF (ρ0ρ0) � BF (ρ+ρ−) so penguins are small
• B0 → ρ+ρ− is > 95% longitudinally polarized
Measurement BaBar Belle
BF (ρ+ρ−) × 10−6 23 ± 2 ± 2 29 ± 5 ± 4
BF (ρ+ρ0) × 10−6 23 ± 6 ± 6 32 ± 7 ± 6
BF (ρ0ρ0) × 10−6 < 1.1
S(ρ+ρ−) −0.33 ± 0.24 ± 0.11 +0.09 ± 0.42 ± 0.08
C(ρ+ρ−) −0.03 ± 0.18 ± 0.09 0.00 ± 0.30 ± 0.10
C(ρ+ρ0) −0.19 ± 0.23 ± 0.03 0.00 ± 0.22 ± 0.03
Eventually can measure S(ρ0ρ0) as well as C(ρ0ρ0)
18
Dalitz analysis of B → πρ
Do a time-dependent
analysis of the
π+π−π0 Dalitz plot
Snyder & Quinn (1993)
A3π = f+A+ + f−A
− + f0A0
where + − 0 is the ρ charge
Sensitivity is in
interference regions 0
5
10
15
20
25
30
0 5 10 15 20 25 30
s+ (GeV2/c4)
s –
(G
eV2 /c
4 )
0
1
2
3
4
5
22 23 24 25 26 27
Interference
√s0 = 1.5 GeV/c 2
√s+
= 1.
5 G
eV/c
2
√s– = 1.5 GeV/c2
|A3π(∆t)|2 ∝ |A3π|2 + |A3π|
2
±(|A3π|2 − |A3π|
2) cos(∆md∆t) ±2Im[A3πA3π] sin(∆md∆t)
19
Summary of α measurements
Combination of all
three modes gives
the best constraint:
α = (99+12−9 )◦
Agrees with CKM fit
using other measurements
0
0.2
0.4
0.6
0.8
1
1.2
0 20 40 60 80 100 120 140 160 180
B → ππB → ρπB → ρρ
CombinedCKM fit
α (deg)
1 –
CL
WACK Mf i t t e r
LP 2005
20
Measuring γ with B → D(∗)K(∗)
All methods use interference between tree diagrams b→ u(sc) and
b→ c(su). The ratio of the diagrams rB depends on the method.
• GLW method: B− → DCPK− with DCP → fCP
Large rate but small interference because rB � 1
• ADS method: B− → D0K−, D0 → K+π− (DCS)
and B− → D0K−, D0 → K+π− (Cabibbo-favoured)
Interference is large but DCS rate is small
• Dalitz method: B− → D0K−, D0 → Ksπ+π−
Interference term comes from D0 Dalitz plot analysis
Errors are very sensitive to value of rB:
BaBar rB = 0.12± 0.08± 0.05 Belle rB = 0.21± 0.08± 0.05
21
D0 → KSπ+π− Dalitz Method
Sensitivity across Dalitz plot
BaBar PRL 95, 121802 (2005)
γ = (67 ± 28 ± 13 ± 11)◦
Belle PRD 70, 072003 (2004)
γ = (64 ± 19 ± 13 ± 11)◦
) 4/c2 (GeV2-m
1 2 3
)
4/c2
(G
eV2 +
m
1
2
3 a)
) 4/c2 (GeV2+m
1 2 3)
4
/c2 (
GeV
2 -m
1
2
3 b)
(a) B− decays (b) B+ decays
22
Measurements of b → c`ν Decays
• Inclusive b→ c`ν using one reconstructed B decay as a tag,
and looking for lepton from other B
- Measure BF (B → `) = 10.95 ± 0.15%
- Moments of lepton energy and hadronic mass spectra
• Exclusive B → D(∗)`ν
- Measure BFs as a function of recoil
- Determine shape of Isgur-Wise function
- Measure form factors
- Vcb from zero-recoil point
23
Heavy Quark parameters from b → c`ν
Remarkable progress in determining quark masses,
non-perturbative QCD parameters and Vcb using the
heavy quark Operator Product Expansion (HQE)
Fit hadronic and leptonic moments in inclusive b→ c`ν decays
|Vcb| = (41.4 ± 0.4(exp) ± 0.4(HQE) ± 0.6(theo)) × 10−3
mb = 4.61 ± 0.05(exp) ± 0.04(HQE) ± 0.02(αs)GeV
mc = 1.18 ± 0.07(exp) ± 0.06(HQE) ± 0.02(αs)GeV
µπ2 = 0.45 ± 0.04(exp) ± 0.04(HQE) ± 0.02(αs)GeV2
µg2 = 0.27 ± 0.06(exp) ± 0.03(HQE) ± 0.01(αs)GeV2
BaBar: PRL 93, 011803 (2004)
24
Determinations of Vcb from B → D(∗)`ν
B0 → D+`−ν
Belle: PLB 526, 258 (2002)
0
0.02
0.04
0.06
0.08
0.1
1 1.1 1.2 1.3 1.4 1.5 1.6y
| Vcb
| F
D(y
)
(41.9 ± 4.5 ± 5.3 ± 3.0) × 10−3
B0 → D∗+`−ν
BaBar: PRD-RC 71, 051502 (2005)
20
25
30
35
1 1.1 1.2 1.3 1.4 1.5
Form
Fac
tor
× |V
cb| ×
103
w
F( )|Vcb|
A1( )|Vcb|
w
w
(38.7 ± 0.3 ± 1.7 ± 1.4) × 10−3
25
Measurements of b → u`ν Decays
• Inclusive b→ u`ν using one reconstructed B decay as a tag and
subtracting the b→ c`ν background:
- Measure lepton energy endpoint spectrum
- Measure q2 from lepton and missing energy (neutrino)
- Measure hadronic mass Mx
• Exclusive B → π`ν and B → ρ`ν using one reconstructed B
decay as a tag:
- Measure BFs as a function of q2
- Use isospin symmetry to relate B+ → π+ and B0 → π0
- Use isospin symmetry to relate B → ρ+, ρ0, ω
26
Inclusive Vub results
BaBar: hep-ex/0509040
Lepton Endpoint analysis ⇒
(b→ c`ν subtracted)
|Vub| = 4.44 × 10−3
±0.25(exp.)
±0.38(shape)
±0.22(theory)
)4/c2 (GeV2q0 5 10 15 20 25
En
trie
s
0
50
100
150
200
250
)4/c2 (GeV2q0 5 10 15 20 25
En
trie
s
0
50
100
150
200
250) < 1.7
2(GeV/cX0.0 < M
)4/c2 (GeV2q0 5 10 15 20 25
En
trie
s
0
100
200
300
400
500
600
700
800
)4/c2 (GeV2q0 5 10 15 20 25
En
trie
s
0
100
200
300
400
500
600
700
800) < 5.0
2(GeV/cX1.7 < M
Data
(in)ν ul→ b (out)ν ul→ b +otherν cl→ b
BABARpreliminary
0
0.05
0.1
2 2.1 2.2 2.3 2.4 2.5 2.6 2.7
Electron Momentum (GeV/c)
∆B(1
0-3)
/ (50
MeV
/c)
BaBar: hep-ex/0507017
⇐Mx/q2 analysis
|Vub| = 4.65 × 10−3
±0.24(stat.)
±0.24(syst.)
±0.42(shape)
±0.23(theory)
27
Inclusive Vub result from Belle: PRL 95, 241801 (2005)
P+ (GeV)
Eve
nts
/ bin
data
b→u MCb→c MC
(a)
0
500
1000
1500
2000
2500
3000
0 1 2 3 4 5
P+ (GeV)
Eve
nts
/ 110
MeV ←signal
region (b)
-20
0
20
40
60
80
100
120
0 0.5 1 1.5 2
P+ = EX − |pX |
|Vub| = 4.56 × 10−3
±0.21(stat.)
±0.32(syst.)
±0.47(shape)
±0.16(theory)
Mx (GeV/c2)
Eve
nts
/ 120
MeV
/c2
←signalregion (a)
-25
0
25
50
75
100
125
150
0 1 2 3 4 5
q2 (GeV2/c2)E
vent
s / 1
40 M
eV2 /c
2
→ signalregion (b)
0
10
20
30
40
50
60
-5 0 5 10 15 20
28
B → π`ν and Summary of Vub
Exclusive B → π`ν with
Lattice QCD form factor
|Vub| = (3.7 ± 0.2+0.9−0.5) × 10−3
Inclusive b→ u`ν with
shape parameters from
b→ c`ν and b→ sγ
|Vub| = (4.4 ± 0.2 ± 0.3) × 10−3
29
b → sγ as a probe of New Physics
Can replace the W and t quark in the “penguin” diagram with new
particles in the loop:
Additional contributions could change the rate of b→ sγ
BF (b→ sγ) = (3.6 ± 0.3) × 10−4 SM (Eγ > 1.6GeV )
BF (b→ sγ) = (3.5 ± 0.3) × 10−4 HFAG (Eγ > 1.6GeV )
This agreement gives important constraints on New Physics
Experimental error can be reduced to 5% with more data
Theory error can be reduced with NNLO calculations
30
Measurements of b → sγ
BaBar: PRD 72, 052004 (2005)
Sum of exclusive modes
Photon spectrum in B rest frame
(GeV)γE1.9 2 2.1 2.2 2.3 2.4 2.5 2.6
Bra
nch
ing
Fra
ctio
n /
100
MeV
-0.05
0
0.05
0.1
0.15
0.2-310×
DataKinetic schemeShape Function scheme
BA BAR
BF = (3.35 ± 0.19+0.56
−0.41 ± 0.06) × 10−4
BF is extrapolated down
to Eγ > 1.6 GeV
Belle: PRL 93,061803(2004)
fully inclusive
photons in Υ(4S) frame
E*γ [GeV]
Eve
nts
/100
MeV
-5000
0
5000
10000
15000
20000
25000
1.5 2 2.5 3 3.5 4
BF = (3.59 ± 0.32 ± 0.31 ± 0.09) × 10−4
Errors are statistical, systematic, theoretical respectively
31
Time-Dependent CP Violation in B → K∗γCouplings are left-handed (right-handed) for b→ sγ (b→ sγ)
S(Ksπ0γ) ∝ ms
mb
sin 2β = 0.042 ± 0.021 C(Ksπ0γ) < 0.01
Matsumori & Sanda hep-ph/0512175
-1-0.5
00.5
1
0.0 < r ≤ 0.5
-1-0.5
00.5
1
-7.5 -5 -2.5 0 2.5 5 7.5
0.5 < r ≤ 1.0
∆t (ps)
Raw
Asy
mm
etry
(b)
Belle:hep-ex/0507059
S(Ksπ0γ) = −0.58 ± 0.42 ± 0.11
C(Ksπ0γ) = −0.03 ± 0.34 ± 0.11
t (ps)∆-6 -4 -2 0 2 4 6
Wei
ghte
d ev
ents
0
10
20
t (ps)∆-6 -4 -2 0 2 4 6
Wei
ghte
d ev
ents
0
10
20 0B
t (ps)∆-6 -4 -2 0 2 4 6
Wei
ghte
d ev
ents
0
10
20
t (ps)∆-6 -4 -2 0 2 4 6
Wei
ghte
d ev
ents
0
10
20 0
B
t (ps)∆-6 -4 -2 0 2 4 6
Asy
mm
etry
-1
-0.5
0
0.5
1
t (ps)∆-6 -4 -2 0 2 4 6
Asy
mm
etry
-1
-0.5
0
0.5
1
BaBar:PRD-RC 72, 051103 (2005)
S(K∗γ) = −0.21 ± 0.40 ± 0.05
C(K∗γ) = −0.40 ± 0.23 ± 0.03
32
Current status of B → ργ
BaBar: PRL 94, 011801 (2005)
2σ excesses in B+(0) → ρ+(ω)γ
but nothing in B0 → ρ0γ
BF (B0→ ρ0γ) < 0.6 × 10−6
Belle: hep-ex/0506079
5σ excess in B0 → ρ0γ
0.8 < BF (B0→ ρ0γ) < 1.5 × 10−6
E (GeV)∆-0.4 -0.2 0 0.2 0.4
En
trie
s/(5
0 M
eV)
0
2
4
6
8
10
12
14
16
18
γ0ρ → 0
B
)2 (GeV/cbcM5.2 5.22 5.24 5.26 5.28 5.3
)2E
ntr
ies/
(4 M
eV/c
0
2
4
6
8
10
12
14 γ0ρ → 0
B
Belle and BaBar
differ by ≈ 3σ
Is isospin broken?
ρ+ : ρ0 : ω 6= 2 : 1 : 1
33
Measuring Vtd/Vts with b → dγ penguins
BF (B → ργ)
BF (B → K∗γ)=
∣
∣
∣
∣
Vtd
Vts
∣
∣
∣
∣
2 (1 −m2ρ/m
2B)3
(1 −m2K∗/m2
B)3ζ2[1 + ∆R]
ζ = 0.85 ± 0.10 allows for SU(3) breaking in the form factor
∆R = 0.1 ± 0.1 allows for weak annihilation (B+ → ρ+γ only!)
BaBar (95% CL)
|Vtd/Vts| < 0.21
Belle (95% CL)
|Vtd/Vts| > 0.14
Currently better
than Bs mixing!
ρ-1 -0.5 0 0.5 1
η
-0.2
0
0.2
0.4
0.6
0.8
1
1.2
)γω/ρ→BR(B
)γ*K→BR(B
ρ-1 -0.5 0 0.5 1
η
-0.2
0
0.2
0.4
0.6
0.8
1
1.2
Is an inclusive measurement of b→ dγ also possible?
34
The rare decays b → s`+`−
q q
b st
W
γ , Z
l +
l −
q q
b st
W +W − ν
l − l +
b sq∼
χ∼ −
h0
µ +
µ −
Wilson coefficients C7, C9 and C10 (sensitive to New Physics) from:
• Inclusive and exclusive (K,K∗) Branching Fractions as a
function of q2 of the leptons
• Forward-Backward lepton asymmetry as a function of q2
(note that this is zero for K`+`−)
• The ratio of se+e−/sµ+µ−
• Direct CP asymmetries
• Eventually b→ d`+`− (using B → π`+`−)
35
Exclusive B → K(∗)`+`−BaBar: hep-ex/0507005 Belle: PRL 91, 261601 (2003)
0
10
20
30
5.2 5.225 5.25 5.275 5.3
(a) K+ e+e-
Eve
nts
/ 2.0
MeV
/c2
0
10
20
30
5.2 5.225 5.25 5.275 5.3
(b) K* e+e-
0
10
20
30
5.2 5.225 5.25 5.275 5.3
(c) K+ µ+µ-
0
10
20
30
5.2 5.225 5.25 5.275 5.3
(d) K* µ+µ-
0
20
40
60
5.2 5.225 5.25 5.275
(e) K+ l+l-
0
20
40
60
5.2 5.225 5.25 5.275 5.3
(f) K* l+l-
Mbc (GeV/c2)
Direct CP asymmetries:
ACP (K``) = 0.08 ± 0.22 ± 0.11
ACP (K∗``) = −0.03 ± 0.23 ± 0.12
36
Measurements of inclusive b → s`+`−
0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 20
0.2
0.4
0.6
0.8
1.0
1.2
10-7
10-6
q2 (GeV/c)2Mxs (GeV/c2)
(b)(a)
dB
/dM
xs(1
0-4
(GeV
/c2)-
1)
dB
/dq
2((
GeV
/c)-
2)
5 10 15 2520
BaBar: PRL 93, 081802 (2004)
BF (b→ s`+`−) = (5.6 ± 1.5 ± 1.3) × 10−6
Belle: hep-ex/0408119
BF (b→ s`+`−) = (4.1 ± 0.8 ± 0.8) × 10−6
BF is in
agreement with
Standard Model
37
Forward-Backward Asymmetry
in B → K∗`+`−
SuperB factory with 50/ab ⇒
or a few years of LHCb data
-1
-0.5
0
0.5
1
0 2 4 6 8 10 12 14 16 18 20q2 GeV2/c2
AF
B (
bkg-
sub)
K* l+ l-negative A7
Belle: hep-ex/0508009
fit favours SM
C7, C10 < 0 and C9 > 0
38
Purely leptonic B decays
B → `ν proceeds via a weak annihilation diagram:
Standard Model prediction:
BF (B+ → τ+ντ ) = 1.2 × 10−4
(
fB
200MeV
)2 (
Vub
0.004
)2
can be modified by an H+ at large tanβ
The decays B+ → µ+νµ and B+ → e+νe are helicity suppressed
τν : µν : eν = 1 : 4 × 10−3 : 1 × 10−7
39
BaBar search for B → τν: hep-ex/0507069
A tag B− is reconstructed as:
⇒ semileptonic B− → D∗0`−ν
⇒ hadronic final states
Plot of extra energy in event
Semileptonic tags
τ → e decays
Combined result from
all tags and decays is
close to expected BF:
τ+ decays to:
e+, µ+, π+, ρ+, a+1
(81% of τ decays)
BF (B+ → τ+ντ ) = 1.3+1.0−0.9 × 10−4 (< 2.6 × 10−4 at 90% C.L.)
40
A hint of New Physics in Gluonic Penguins?
sin(2βeff)/sin(2φe1ff)
HF
AG
HE
P 2
005
HF
AG
HE
P 2
005
HF
AG
HE
P 2
005
HF
AG
HE
P 2
005
HF
AG
HE
P 2
005
HF
AG
HE
P 2
005
HF
AG
HE
P 2
005
HF
AG
HE
P 2
005
HF
AG
HE
P 2
005
b→ccs
φ K
0η′
K0
f 0 K
S
π0 KS
π0 π0 K
S
ω K
S
K+ K
- K0
KS K
S K
S
-3 -2 -1 0 1 2 3
World Average 0.69 ± 0.03BaBar 0.50 ± 0.25 +-
00
.
.00
74
Belle 0.44 ± 0.27 ± 0.05Average 0.47 ± 0.19BaBar 0.36 ± 0.13 ± 0.03Belle 0.62 ± 0.12 ± 0.04Average 0.50 ± 0.09BaBar 0.95 +-
00
.
.23
32 ± 0.10
Belle 0.47 ± 0.36 ± 0.08Average 0.75 ± 0.24BaBar 0.35 +-
00
.
.33
03 ± 0.04
Belle 0.22 ± 0.47 ± 0.08Average 0.31 ± 0.26BaBar -0.84 ± 0.71 ± 0.08Average -0.84 ± 0.71BaBar 0.50 +-
00
.
.33
48 ± 0.02
Belle 0.95 ± 0.53 +-00
.
.11
25
Average 0.63 ± 0.30BaBar 0.41 ± 0.18 ± 0.07 ± 0.11Belle 0.60 ± 0.18 ± 0.04 +-
00
.
.11
92
Average 0.51 ± 0.14 +-00
.
.10
18
BaBar 0.63 +-00
.
.23
82 ± 0.04
Belle 0.58 ± 0.36 ± 0.08Average 0.61 ± 0.23
H F A GH F A GHEP 2005
PRELIMINARY
sin 2β(b→ s) 6= sin 2β(b→ ccs)
“Naive” average sin 2βeff = 0.50 ± 0.06
Cf = -Af
HF
AG
HE
P 2
005
HF
AG
HE
P 2
005
HF
AG
HE
P 2
005
HF
AG
HE
P 2
005
HF
AG
HE
P 2
005
HF
AG
HE
P 2
005
HF
AG
HE
P 2
005
HF
AG
HE
P 2
005
φ K
0
η′ K
0f 0
KS
π0 KS
π0 π0 K
S
ω K
S
K+ K
- K0
KS K
S K
S-1.8 -1.6 -1.4 -1.2 -1 -0.8 -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8
BaBar 0.00 ± 0.23 ± 0.05Belle -0.14 ± 0.17 ± 0.07Average -0.09 ± 0.14BaBar -0.16 ± 0.09 ± 0.02Belle 0.04 ± 0.08 ± 0.06Average -0.07 ± 0.07BaBar -0.24 ± 0.31 ± 0.15Belle 0.23 ± 0.23 ± 0.13Average 0.06 ± 0.21BaBar 0.06 ± 0.18 ± 0.03Belle -0.11 ± 0.18 ± 0.08Average -0.02 ± 0.13BaBar 0.27 ± 0.52 ± 0.13Average 0.27 ± 0.54BaBar -0.56 +-
00
.
.22
97 ± 0.03
Belle -0.19 ± 0.39 ± 0.13Average -0.44 ± 0.23BaBar 0.23 ± 0.12 ± 0.07Belle 0.06 ± 0.11 ± 0.07Average 0.14 ± 0.10BaBar -0.10 ± 0.25 ± 0.05Belle -0.50 ± 0.23 ± 0.06Average -0.31 ± 0.17
H F A GH F A GHEP 2005
PRELIMINARY
... but no direct CP violation
Cf = −0.04 ± 0.04
41
Effect of SUSY b→ s couplings - Silvestrini hep-ph/0510077
Already includes constraints from b→ sγ and b→ s`+`−
42
Next to Minimal Flavour Violation
General class of new physics models - Agashe et al. hep-ph/0509117
• Flavour structure quasi-aligns with SM Yukawa couplings
• New couplings are dominantly to third generation quarks
Constraints on magnitude hd and phase φd of new b→ d coupling
43
b Physics programme at LHCb
For many B+ and B0 decays:
one year of data matches all the data from the B factories...
... but there are also plenty of Bs, Bc and Λb!
A personal list of interesting measurements:
• Accurate measurements of ∆ms and ∆Γs
• Constraints on φs from time-dependent CP violation in
Bs → J/ψφ
• Measurements of γ using Bs → DsK and Bs → K+K−
• Search for new physics in b→ s penguins using rare decays of
Bd and Bs to φ and η′
• Measurements of asymmetries in B → K∗`+`−
44
Bs mixing
CKM fit predicts:
∆ms = 18.3+6.5−1.5
Should eventually be
measured at Tevatron ⇒
and at LHCb ⇓ ]-1
[pssm∆0 5 10 15 20
Am
plitu
de
-4
-2
0
2
4 σ 1 ± data
σ 1.645
σ 1.645 ± data
(stat. only)σ 1.645 ± data
95% CL limit
sensitivity
-18.6 ps-113.0 ps
π(3)-s D→ 0
sX, B+l-s D→ 0
s B
CDF Run II Preliminary (Fall 2005) -1 355 pb≈L
predictedσ 1.645
...or new
Physics
at LHCb?
45
Super B Factories?
e+e− colliders at the Υ(4S) after BaBar/BELLE/LHCb
• SuperBELLE at KEK:
– Luminosity: 2 − 5 × 1035∫
= 20ab−1
– Timescale: 2011-2020 Cost: 450M$
– Proposal is under review in Japan
• SuperBaBar:
– Luminosity: 5 − 7 × 1035∫
= 50ab−1
– Timescale: 2013-2020 Cost: ≈ 500M$
– Not supported by SLAC/US at present
• Linear Collider Super B:
– Luminosity: 1 − 2 × 1036∫
≈ 100ab−1
– Feasibility is being studied at Frascati
46