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Recent results on CP violation in B decays
Marcello A. Giorgi UniversitÞ di Pisa and INFN Pisa
presented at XXXII International Conference on High Energy Physics Beijing, China August 16-22, 2004


Current luminosities and data samples
Total 244 +
300 250 200

286 fb-1 = 0.530 ab-1!!
Delivered Recorded Continuum

17fb-1/month
L
peak

= 9.2 â 10 cm s
33

-2 -1

150 100 50 0

22fb-1/month
L
peak

= 14 â 1033 cm -2 s

-1

10/11/04

9/11/00

1/21/02

5/3/99

6/2/03

ICHEP04August 20, 2004

Marcello A. Giorgi

2


BABAR Detector
EMC 6580 CsI(Tl) crystals 1.5T solenoid DIRC (PID) 144 quartz bars 11000 PMs

e+ (3.1GeV)

e- (9GeV)

Drift Chamber 40 layers

Instrumented Flux Return iron / RPCs (muon / neutral hadrons)

Silicon Vertex Tracker 5 layers, double sided strips

ICHEP04August 20, 2004

Marcello A. Giorgi

3


CKM and unitarity conditions
qi = u, c, t
W
+

Vij

q j = d , s, b

( , )

V ud V = V cd V td
VtdVtb VcdVcb

V

us

V cs V ts

Vub V cb V tb

VudV VcdV

ub cb

[2 ]

(b u )
(0, 0)
[3

B0 - B 0 mixing
[1

]

]

B and b c ) (
Marcello A. Giorgi

(1, 0)

ICHEP04August 20, 2004

4


3 ways for CP violation
1. CP violation in mixing
q = p
* 12 (M - i ) 2 1 ( M 12 - i 12 ) 2 * 12

q/p

f
0



q/p

f
0

B0 B

B0 B
SM predicts:

First mechanism observed historically in kaon decays
-4

mc2 q - 1 4 2 sin 5 â 10 p mt
f
2

2. Direct CP violation in the decay

A



A B
0

2

B

0

f

Occurs when A / A 1 where A is the amplitude for B decays into a final state f and A is the amplitude of B decays into the CP conjugate state f.

Two amplitudes A1 and A2 relative CP violating phase a CP conserving phase CP violation and A
ICHEP04August 20, 2004

with a 2 and : A .

Marcello A. Giorgi

5


First observation of Direct CPV in B decays
B 0 K +
BABAR BABAR
-

hep-ex/0408057, submitted to PRL

Signal (227M BB pairs): 1606 ± 51

ACP =-0.133 ± 0.030 ± 0.009
Belle Belle

4.2

B 0 K + BABAR 0 BABAR B K -

- +

Confirmation at ICHEP04

Signal (274M BB pairs): 2140 ± 53

ACP =-0.101 ± 0.025 ± 0.005
Average

3.9

ACP =-0.114 ± 0.020
0

B + K +

ACP =+0.06 ± 0.06 ± 0.01 BABAR 3.6 ACP =+0.04 ± 0.05 ± 0.02 Belle
Average

ACP =+0.049 ± 0.040
Marcello A. Giorgi

ICHEP04August 20, 2004

J. Wu, Y.Chao, CP-6

6


3 ways for CP violation
3.Time dependent
Define CP Asymmetry as:

Decay+mixing B0
No oscillation Net oscillation

fCP

A

f

CP

(t )

=

B (B
f

(

0 phys 0 phys

(t ) (t )

f f

CP

CP

)

)

- (B + B

(

0 phys

(t ) (t )

f f

CP

)

0 phys

CP

)

B0
fCP

A

f

CP

= -C

CP

cos(mt ) + S

f

CP

sin(mt )
| |
f

B0

Decay+mixing
No oscillation Net oscillation

B0



f

CP

qA = pA

Amplitude ratio
f f
CP CP

C
S

f

CP

=
=

1- | 1+ |
1+ |

2 2

For single amplitude

f f

CP

=0
= - Im

CP

(B (B

0 phys 0 phys

(t ) f (t ) f

CP

) )

CP parameter

e

-2 i

-2Im
f
CP

CP

f

CP

|

2

f

CP

CP

C

f

CP

0 implies Direct CP Violation
7

ICHEP04August 20, 2004

Marcello A. Giorgi


Measuring time-dependent CP asymmetries
Tagging performance: Q = 30.5%

z

(4 S )

= 0.55

µ

-

Flavor Flavor Tagging Tagging

e

-

( 4S

)

B
e
+

K

-

tag

Tag vertex Tag vertex reconstrruction reconst uction

B
t z

rec

µ

-

J /



1 c

z

K

0 S

µ

+

t is a signed quantity


Start the Clock
Marcello A. Giorgi

-



+

t ~ 1 ps 170 µ m B ~ 1.6 ps 250 µ m
ICHEP04August 20, 2004

Exclusive B Meson and vertex Exclusive B Meson and vertex reconstrruction reconst uction
8


sin2 results from charmonium modes
0 (cc ) K S (CP odd) modes

BABAR BABAR

Belle Belle
2003 2003

bkg

Update for ICHEP04

BABAR PUB-04/038

Belle CONF-0436

Limit on 205 fb -1 on peak or 227 M BB pairs direct CPV 7730 CP events (tagged signal)
ICHEP04August 20, 2004

0 sin 2 =+0.722 ± 0.040 ± 0.023 (cc ) K S + sin 2 = +0.728 ± 0.056 ± 0.023 0 = A / A = 0.950 ± 0.031 ± 0.013 (cc ) K L = A / A = 1.007 ± 0.041 ± 0.033

140 fb -1 on peak or 152M BB pairs 4347 CP events (tagged signal)
M.Bruinsma, T. Higuchi, CP-3

Marcello A. Giorgi

9


sin2, cos2 and CKM constraints
BABAR BABAR
cos2 < 0 cos2 > 0

cos2 < 0 ruled out at 87% CL by s- and p-wave interference in angular analysis of BJ/K*0 (KS0)
M.Bruinsma, CP-3

[

sin 2

]WA

= +0.726 ± 0.037

( stat + sys )

CKM fit to indirect constraints overlaid with sin2WA measurement

ICHEP04August 20, 2004

Marcello A. Giorgi

10


Methods for extraction of
is phase between b u ( Vub ) and b c ( Vcb ) amplitudes
Basic Idea Use interference between B - D 0 K - and B - D 0 K - decays where the D 0 ( D 0 ) decay to a common final state f
* Vus * A VubVcs 3

2 +2 e

i

Vub Vcb A VcbVu*s
3

V
GLW Gronau-London-Wyler, 1991 0 Use B - DCP ± K - decays

* cs

Color suppressed

Atwood-Dunietz-Soni, 2001 Use B - D (*) 0 K + - K - decays 0 D0 Dalitz plot Use B - D (*) 0 K S + - K - decays ADS
ICHEP04August 20, 2004 Marcello A. Giorgi

Size of CP asymmetry depends on (*) 0 | A( B - D K - ) | ~0.1 - 0.3 rB(*) (*) 0 - - | A( B D K ) |

11


B- D
B D K
0

(*)0[K+ -
0

]K- decays: ADS method
+ -

favored
-

-

D K
-

suppressed favored

R

ADS

BF ([ K + - ]K - ) + BF ([ K - + ]K + ) = ~ rB2 BF ([ K - + ]K - ) + BF ([ K + - ]K + )

suppressed

B D K
Update for ICHEP04

-

0

D K +
From limit on D 0 K + - K -

0

[ K + - ] D K
-

-

rB < 0.23 (90% CL)

BABAR BABAR

* rB < 0.21 (90% CL)

From limit on D*0 K + - K -

R

ADS

Belle Belle
rB < 0.28 (90% CL)
ICHEP04August 20, 2004

rB
Marcello A. Giorgi

BABAR CONF-04/013

* rB

G.Cavoto, A.Bozek, CP-4

12


First look at B- D
New: Winter 04

(*)0[K
M2(KS-) [GeV2]

S

+-]K- sample by Belle
M2(KS-) [GeV2]

Belle Belle 140 fb-1 140 fb-1

B D0 K

+

B D0 K

-

Visible asymmetry in Dalitz plots

M2(KS-) [GeV2]

Parameters: , rD , rD* , D ,

D

*

M2(KS+) [GeV2]

M2(KS+) [GeV2]
M2(KS-) [GeV2]

= 77o +17 ± 13 ± 11( model ) -19 26 < < 126o [95% CL]
rB = 0.26 +0.10 ± 0.03 ± 0.04 -0.14 * rB = 0.20 +0.19 ± 0.02 ± 0.04 -0.17
ICHEP04August 20, 2004

B D*0 K

+

B D*0 K

-

M2(KS+) [GeV2]

M2(KS+) [GeV2]
hep-ex/0406067

Marcello A. Giorgi

A.Bozek, CP-4

13


BABAR analysis of B- D
68% 90% [deg]
New for ICHEP04

(*)0[K
D0 K
-

S

+-]K

-
D*0 K
-

BABAR BABAR

D0 K
[deg]

-

rB

rB < 0.17 (90% CL) * rB < 0.23 (90% CL)

rB

* rB

[No sensitivity to rB < 0.1]

D*0 K
BABAR CONF-04/043 ICHEP04August 20, 2004

-

B = (130 ± 45 ± 8 ± 10( model ) )o * B = (311 ± 52 ± 23 ± 10( model ) )o = (88 ± 41 ± 19 ± 10( model ) )o
* rB

Poor constraints on as yet
G.Cavoto, CP-4
14

Marcello A. Giorgi


sin2 from B , ,
Interference of suppressed b u "tree" decay with mixing but: "penguin" is sizeable!

B0 mixing
b d d b

B0 decay: tree

B0 decay: penguin


* A VubVud 3


* A VtdVtb 3

* q / p VtbVtd VtbVtd

q A = = e-i 2 e-i 2 = ei p A
S = sin 2 C = 0

2

= ei

2

T + Pe+i ei T + Pe-i ei

Coefficients of time-dependent CP Asymmetry
With no penguins With large penguins and |P/T| ~ 0.3
2 S = 1 - C sin 2 C sin eff

ICHEP04August 20, 2004

Marcello A. Giorgi

15


Results for sin2eff from B decays
BABAR: Updated for ICHEP04

B (227M pairs)
0

+

-

BABAR BABAR

S =-030 ± 0.17 ± 0.03 . C =-0.09 ± 0.15 ± 0.04
Belle: PRL 93 (2004) 021601

S =-1.00 ± 0.21 ± 0.07 C =-058 ± 0.15 ± 0.07 . 152M pairs

BABAR CONF-04/047, 04/035

Comparison

B ± ± 0 (227M pairs) A ± 0 = -0.01 ± 0.10 ± 0.02 BF ± 0 = (5.8 ± 0.6 ± 0.4) â 10
Marcello A. Giorgi
-6

Caution averaging!
ICHEP04August 20, 2004

M.Cristinziani, CP-5

16


Updated for ICHEP04

Result for B 0

0

Fit = qq bkgd + B 0 ± 0 + signal

BABAR CONF-04/035

Improved understanding of 0 efficiency: data / MC = 0.99 ± 0.03 vs 0.88 ± 0.08
BABAR

BB pairs
122M 105M

N ( 0 0 )
44±13 17±11

BF 0 0 = (1.17 ± 0.32 ± 0.10) â 10-6 4.9 First C 0 0 =-0.12 ± 0.56 ± 0.06 measurements

Run 1-3 Run 4

-
BF C

00

eff

35o at 90% CL

Run 1-4 227M 61±17 Consistent at 1.3 level
ICHEP04August 20, 2004



00

= (2.32 +0.41 +0.22) â 10-6 6.0 -0.48 -0.18 +0.16 First . =-043 ± 0.51 -0.17 measurements
M.Cristinziani, CP-4; Y.Chao, CP-6
17

Marcello A. Giorgi


Results for sin2eff from B decays
Extraction of similar to , but with advantage of smaller Penguin pollution:
| A00 | | A00 | , + - much smaller: - eff smaller +0 |A | |A | Potentially + - could be mixed CP, but is observed to be almost pure CP = +1
Moriond QCD04

BABAR BABAR

B 0 + - (122M BB pairs)
Signal: 314 ± 34 events flong = 1.00 ± 0.02 Slong =-0.19 ± 0.33 ± 0.11 Clong =-023 ± 0.24 ± 0.14 . hep -ex / 0404029 tBB o PRL (89M BB pairs) Slong =-042 ± 0.42 ± 0.14 . Clong =-0.17 ± 0.27 ± 0.14
ICHEP04August 20, 2004 Marcello A. Giorgi

C.Dallapiccola, CP-6

18


Isospin Corrections for
B0 +
+

0

PRL 91 (2003) 171802

First result from Run 1-2 (89M BB pairs)

BF ( B ) = (22.5 +5.7 ± 5.8) â 10 -5.4
+ 0

-6

BABAR BABAR

B0 0

0

Updated for ICHEP04
BABAR CONF-04/037

Updated result from Run 1-4 (227M BB pairs)

BF ( B 0 0 0 ) < 1.1â 10-6 (90% CL) A+- A+- 2 2 A00 2 peng A00 = 96 ± 10 A+0 = A+0
Geometric limit on 2
ICHEP04August 20, 2004
peng: Grossman-Quinn bound

( stat )

±4

( sys )

± 11(

peng )



o

Compare with 35o for
C.Dallapiccola, CP-6
19

Marcello A. Giorgi


Basis for Dalitz plot analysis of B0 ()0
Quasi-two-body approach to Snyder-Quinn method Phys.Rev. D 48, 2139 (1993) · Extract and strong phases using interference between amplitudes · Amplitude A3 dominated by +-, -+,00 and radial excitations · Form time-dependent decay rate coefficients of cos(mdt) and sin(mdt) on this basis

S

-



0

+-



0

-+
ICHEP04August 20, 2004 Marcello A. Giorgi

S
20

+


Results from Dalitz analysis of B0 ()
Evidence for direct CP: 2.9
+- A

0

Belle [152M]
ACP

BABAR [213M]

BABAR BABAR BABAR BABAR

-+ A

-0.16 +0.09 -0.088 ± 0.049 ± 0.013 -0.10 S -0.28 ± 0.23 +0.10 -0.10 ± 0.14 ± 0.04 -0.08 C 0.25 ± 0.17 +0.02 0.34 ± 0.11 ± 0.05 -0.06 A+- -0.02 ± 0.16 +0.05 -0.21 ± 0.11 ± 0.04 -0.02 A-+ -0.53 ± 0.29 +0.09 -0.47 ± 0.15 ± 0.06 -0.04 combined 3.6

= (102 ± 11 ± 15)

o

[Based on factorization & SU(3); Gronau & Zupan]

+ = (113 -27 ± 6) 17
BABAR CONF-04/038

o

[degrees]
ICHEP04August 20, 2004

hep-ex/0408003

Marcello A. Giorgi

M.Cristinziani, CP-5; A.Somov, CP-6 21


Summary of constraints on
BABAR & Belle BABAR & Belle combined combined

Mirror solutions disfavored

From combined , , results: o +12 = 100 -11
CKM indirect constraint fit: = 98 ± 16o

ICHEP04August 20, 2004

Marcello A. Giorgi

22


CKM constraints and sin2 and measurements

CKM fit to indirect constraints overlaid with sin2WA and measurements

ICHEP04August 20, 2004

Marcello A. Giorgi

23


Beyond the Standard Model?
Do and yield the same sin2 ?


sin2 and.....

and....

In SM interference between B mixing, K mixing and Penguin bsss or bsdd gives the same e-2 as in tree process bccs. However loops can also be sensitive to New Physics!

W
b

+

u,c , t g

b b

~ g
(d ~ + RR)23 bR ~ g sR

s s

B

0

s s s d s d

, , ( KK )
K
0 S

B CP

0

B

0

s s

,' , ( KK )
0 Ks S

CP

d

d d
~ g

s s dK d
s s

W b

+

New phases from SUSY?
b b
0

u,c , t g

B

0

K

0 S

B

B

0

(d ~ + RR)23 bR ~ g sR

s d

K0' S

d

d d



0

d d

d s d d



Ks

0

ICHEP04August 20, 2004

Marcello A. Giorgi

25


BABAR results for B0 K0
2004 = 227MBB pairs (2003 = 120M pairs) pairs (2003 = 120M pairs)
2003 result

BABAR BABAR
K
0 S

-CP S C
K
0

= +047 ± 0.34 +0.08 . K -0.06 =+010 ± 0.33 ± 0.10 .
0

Update for ICHEP04

B0 K
K
0 L

0 S 0 L

114 ± 12 events S K 0 =+0.29 ± 0.31
S

B0 K
-

98 ± 18 events S K 0 =-1.05 ± 0.51
L

-CP S C
K
0

= +050 ± 0.25 +0.07 . K -0.04 =+000 ± 0.23 ± 0.05 .
0

BABAR-CONF 04/033 ICHEP04August 20, 2004

Marcello A. Giorgi

A.Hoecker, CP-4

26


More BABAR results from b sss penguins
Update for ICHEP04
BABAR CONF-04/025
0 B 0 ( K + K - )CP K S (208M pairs)

· Independent sample with (K+K-) mass outside region · CP content can be determined experimentally with an angular moment analysis through the helicity angle distribution

BABAR BABAR

Signal: 481 ± 29 events f even = 0.89 ± 0.08 ± 0.04
S
KKK
0 S

=-0.42 ± 0.17 ± 0.04
KKK KKK
0 S 0 S

-(2 f

even

- 1) S C

= +0.55 ± 0.22 ± 0.04 ± 0.11 =+0.10 ± 0.14 ± 0.06

ICHEP04August 20, 2004

Marcello A. Giorgi

A.Hoecker, CP-4

27


More BABAR results from b sss penguins
CONF 04/040 CONF 04/019

BABAR BABAR

BABAR BABAR

Updates for ICHEP04

B 0 K
-

208M BB pairs
, , + - 0 0 K S + - , 0
0 + 0

Signal: 819 ± 38 sin 2 [cc ] @ 3.0

0 S

B0 f0 K
-CP S C
f0 K
0 S

0 S

Signal: 152 ± 19

-CP S K 0 = +0.27 ± 0.14 ± 0.03 S C K 0 =-021 ± 0.10 ± 0.03 .
S

= +095 +0.32 ± 0.10 . 0 f0 K S -0.23 =-024 ± 0.31 ± 0.15 .
28

ICHEP04August 20, 2004

Marcello A. Giorgi

A.Hoecker, CP-4


Still another penguin mode: B0 0KS
Beam y constraint

x

B
e
-

0
0

(4S

)B

K e+
0 S

+ - 0

BABAR technique from 2003
Updated for ICHEP04

Btag

BABAR BABAR

BABAR CONF-04/030

227 M BB pairs

[sPlots: Pivk, Le Diberder, physics/0402083]

Signal: 192 w/vertex, 108 w/o -CP S 0 K 0 = +035 +0.30 ± 0.04 . -0.33 S C 0 K 0 =+006 ± 0.18 ± 0.06 .
S

Belle Belle BABAR BABAR
ICHEP04August 20, 2004 Marcello A. Giorgi

274 M BB pairs

Signal: 77 w/vertex, 173 w/o -CP S 0 K 0 = +0.30 ± 0.59 ± 0.11 S C 0 K 0 =-0.12 ± 0.20 ± 0.07
S

A.Hoecker, CP-4; C.F. Chen, CP-3 29


Results on sin2 from s-penguin modes
All new! All new!

2.7 from s-penguin to sin2 (cc)
ICHEP04August 20, 2004

2.4 from s-penguin to sin2 (cc)

Marcello A. Giorgi

30


Projections for Penguin Modes
0.40 0.35 Error on sine amplitude 0.30 0.25 0.20 0.15 0.10 0.05 0.00 Jul-03 Jan-03 Jan-04

f0KS KS0 KS 'KS KKKS

Luminosity expectations:
K* 2004=240 fb-1 2009=1.5 ab-1 Similar projections for Belle as well

5 discovery region if non-SM physics is 20% effect 2004
Jul-04 Jul-05 Jul-06 Jul-07 Jul-08 Jan-05 Jan-06 Jan-07 Jan-08 Jan-09

2009
Jul-09

Projections are statistical errors only; but systematic errors at few percent level
ICHEP04August 20, 2004 Marcello A. Giorgi 31


Conclusions and outlook
· Success of B Factory experiments BaBar and Belle of bccs (new sin2 value from charmonium 0.726 ± 037) · Good agreement between BaBar and Belle results on bsss penguin, but both experiments still show discrepancies (2.7 and 2.4) with charmonium!! · Observation by BaBar of direct CP violation in charmless B decays confirmed by Belle (average value ACP = -0.114 ± 0.020 )
+8 · Quantitative measurements of (2) are emerging (new value = 106 -11)
o

· Constraints on (3) are still poor with present statistics (low values for rB).

· A statistical increase on these modes in the next few years could well provide initial evidence for new physics in the unitarity triangle beyond the SM. · Modes dominated by penguin amplitudes as B0 K0 seem to be promising benchmarks for New Physics at a mass scale < 1 TeV. However unravelling the full flavour impact of this new physics will require a very high luminosity B Factory ­ a Super-B Factory ­ (luminosity higher by a factor 50-100 than in the present machines).
ICHEP04August 20, 2004 Marcello A. Giorgi 32


Backup Slides


Results on sin2 from ccs, dcc modes

ICHEP04August 20, 2004

Marcello A. Giorgi

34


B flavor tagging and t measurement
QT =


i

i (1 - 2 i )

2

(S

f

CP

)

1 N â QT

Tagging performance QT=30.5% (6 categories) from full Neural Network including these & other physics processes to identify b quark state perfect resolution
B 0 ( B 0 ) tag

smeared resolution
B 0 ( B 0 ) tag

tt resolution dominated resolution dominated by tag side: by tag side: (t) 1 ps 170 µm (t) 1 ps 170 µm B 1.6 ps



250 µm

CP asymmetry
ICHEP04August 20, 2004 Marcello A. Giorgi 35


cos2 from B0 J/K*0(KS0)
· J/K*0 (KS0) final state can be F = +1 or F = -1, depending on L = 0, 1, 2 · Full angular analysis allows for the separation of CP even (A|| =| A|| | e i ||, A0 =| A0 | e and CP odd (A =| A | e i) · Many terms in time-dependent decay rate, but two are proportional to cos2
i 0

)

cos 2 =±2.72 ± +0.50 ± 0.027 -0.79
(with sin(2) fixed to 0.731) Sign ambiguity is related to the sign of strong phase difference
· Use interference of s-wave and p-wave contributions to K final state to resolve sign ambiguity for strong phases Assuming: cos 2 =± 1 - sin 2 2
ICHEP04August 20, 2004

BABAR BABAR BABAR

d ( S - 0 ) <0 dm K
solution 1: unphysical solution solution 2: physical solution LASS data
36

cos 2 = -0.68 excluded at 86% CL

Marcello A. Giorgi


Dalitz analysis of B- D
For B : | A- | =| f (m , m ) + rb e
2 2 - 2 +

(*)0[K
2 +

S

+-]K
2

-
2 2

-

i ( - )

f (m , m ) |

2 -

2 0 m- = M ( K S - ) 2 0 m+ = M ( K S + )

m A- =
2

2 -

D

0

m
+ re b

2 -

D

0

2
Schematic view of the interference

i ( + )

2 m+
2 2 For B - : | A- |2 =| f ( m- , m+ ) + rb e

2 m+ i ( + )
2 2 f (m+ , m- ) |2

Two-fold ambiguity remains in extraction of ( + )

ICHEP04August 20, 2004

Marcello A. Giorgi

37