Results from the B factories Steve Playfer, University of Edinburgh · 2008. 10. 22. · CP...

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


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


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


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

Results from the B factories Steve Playfer, University of Edinburgh · 2008. 10. 22. · CP...

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Transcript of Results from the B factories Steve Playfer, University of Edinburgh · 2008. 10. 22. · CP...