Transcript Recent results on CP violation in B decays Marcello A. Giorgi Università di Pisa and INFN Pisa presented at XXXII International Conference on High Energy.

Recent results on CP violation
in B decays
Marcello A. Giorgi
Università 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
286 fb-1 = 0.530 ab-1!!
+
Delivered
Recorded
Continuum
300
250
200
22fb-1/month
17fb-1/month
L peak  9.2  1033 cm 2 s 1
150
L peak  14  1033 cm 2 s 1
100
50
0
10/11/04
6/2/03
1/21/02
Marcello A. Giorgi
9/11/00
5/3/99
ICHEP04August 20, 2004
2
BABAR Detector
EMC
6580 CsI(Tl) crystals
e+ (3.1GeV)
1.5T solenoid
DIRC (PID)
144 quartz bars
11000 PMs
Drift Chamber
40 layers
e- (9GeV)
Silicon Vertex Tracker
5 layers, double sided strips
Instrumented Flux Return
iron / RPCs (muon / neutral hadrons)
ICHEP04August 20, 2004
Marcello A. Giorgi
3
CKM and unitarity conditions
W
 Vud
V   Vcd

V
 td
qi  u, c, t
Vij
q j  d , s, b

(  , 

VudVub
VcdVcb  2 
VtdVtb
VcdVcb
(b  u  )
(0, 0
ICHEP04August 20, 2004
 3 
Vcs
Vts
Vub 
Vcb 

Vtb 
B0  B 0
mixing
 1 
 B and (b  c  )
Marcello A. Giorgi
Vus
(1, 0 
4
3 ways for CP violation
f
q/p
1. CP violation in mixing

B 0 B0
q

p
*
12
B
First mechanism
observed historically
in kaon decays
B0 B 0
mc2
q
 1  4 2 sin   5  104
p
mt
A
0
f
SM predicts:
12*
(M  i )
2 1

( M 12  i 12 )
2
2. Direct CP violation
in the decay
q/p
2
f
A

B
0
2
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 with a
relative CP violating phase 2 and
a CP conserving phase d :
CP violation and A  A.
ICHEP04August 20, 2004
Marcello A. Giorgi
5
First observation of Direct CPV in B decays
B0  K  
BABAR
Signal (227M BB pairs): 1606  51
hep-ex/0408057,
submitted to PRL
0
 
B

K

BABAR 0
B  K  
ACP  0.133  0.030  0.009
4.2s
Belle
Confirmation at ICHEP04
Signal (274M BB pairs): 2140  53
ACP  0.101  0.025  0.005
3.9s
Average
ACP  0.114  0.020
B  K  0
ACP  0.06  0.06  0.01 BABAR
3.6s
ACP  0.04  0.05  0.02 Belle
Average
ACP  0.049  0.040
ICHEP04August 20, 2004
Marcello A. Giorgi
J. Wu, Y.Chao, CP-6
6
3 ways for CP violation
3.Time dependent
Define CP Asymmetry as:
Decay+mixing
B0
Net oscillation
B0
fCP
No oscillation
B0
Decay+mixing
0
 ( B phys
(t )  f CP 

0
 ( B phys (t )  f CP 
ICHEP04August 20, 2004
B0

( t   fCP
(B
0
phys
( t   fCP   
(B
0
phys
( t   fCP

AfCP  C fCP cos(mt )  S fCP sin(mt )
Amplitude
ratio
fCP
No oscillation
Net oscillation
AfCP ( t  
(
0
  ( Bphys
( t   fCP 
 B
0
phys
λ fCP
q AfCP
 
p AfCP
e
2i 
CP parameter
C fCP 
S fCP 
1 |  fCP | 2
1 |  fCP |
2
2Im  fCP
1 |  fCP |
2
For single
amplitude
0
  Im  fCP
C fCP  0 implies Direct CP Violation
Marcello A. Giorgi
7
Measuring time-dependent CP asymmetries
Tagging performance: Q = 30.5%
z

  (4 S )  0.55
e
-
 ( 4S 
K
B
tag
Tag vertex
reconstruction
e
B
rec
t 
z 1
 c
z
t is a signed quantity
s t ~ 1 ps  170  m
 B ~ 1.6 ps  250  m
Start the Clock
ICHEP04August 20, 2004
Flavor
Tagging
Marcello A. Giorgi
  J /


K S0


Exclusive B Meson and vertex
reconstruction
8
sin2 results from charmonium modes
(cc ) KS0 (CP odd) modes
Belle
BABAR
2003
bkg
Update for ICHEP04
Belle CONF-0436
BABAR PUB-04/038
sin 2   0.722  0.040  0.023 (cc ) K S0 + sin 2   0.728  0.056  0.023
  A / A  0.950  0.031  0.013 (cc ) K L0   A / A  1.007  0.041  0.033
Limit on 205 fb 1 on peak or 227 M BB pairs
direct CPV 7730 CP events (tagged signal)
ICHEP04August 20, 2004
140 fb 1 on peak or 152M BB pairs
4347 CP events (tagged signal)
Marcello A. Giorgi
M.Bruinsma, T. Higuchi, CP-3
9
sin2β, cos2β and CKM constraints
BABAR
cos2β < 0
cos2β > 0
cos2 < 0 ruled out at 87%
CL by s- and p-wave
interference in angular
analysis of B J/K*0 (KS0)
M.Bruinsma, CP-3
sin 2 WA  0.726  0.037( stat sys )
ICHEP04August 20, 2004
Marcello A. Giorgi
CKM fit to indirect
constraints overlaid with
sin2βWA measurement
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
A  VubVcs*   3  2   2 ei
Vus*
Vub
Vcb
*
cs
V
A  VcbVus*   3
GLW Gronau-London-Wyler, 1991
0

Use B  DCP
K
decays

ADS
Atwood-Dunietz-Soni, 2001
Use B   D(*)0  K    K  decays
D0 Dalitz plot
ICHEP04August 20, 2004
Color
suppressed
Size of CP asymmetry depends on
(*)0

|
A
(
B

D
K) |
(*)
rB 
~ 0.1  0.3

(*)0

| A( B  D K ) |
Use B   D(*)0  K S0    K  decays
Marcello A. Giorgi
11
B  D(*)0[K]K decays: ADS method
favored

B D K
0
suppressed
D K 

0
suppressed
0

B D K



[ K   ] D K 
favored
0
D  K  
rB  0.23 (90% CL)
Update for
ICHEP04
RADS
BF ([ K   ]K  )  BF ([ K   ]K  )
2

~
r
B
BF ([ K   ]K  )  BF ([ K   ]K  )
BABAR
From limit on
D 0  K    K 
rB*  0.21 (90% CL)
From limit on
D*0  K    K 
R ADS
Belle
rB  0.28 (90% CL)
ICHEP04August 20, 2004
rB
Marcello A. Giorgi
BABAR CONF-04/013
G.Cavoto, A.Bozek, CP-4
rB*
12
Parameters:
 , rD , rD* , d D , d D*
17  13  11
  77o 
( 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
M2(KS-) [GeV2]
Visible asymmetry in Dalitz plots
B  D0 K 
M2(KS+) [GeV2]
B  D*0 K 
B  D0 K 
M2(KS+) [GeV2]
M2(KS-) [GeV2]
Belle
140 fb1
M2(KS-) [GeV2]
New: Winter 04
M2(KS-) [GeV2]
First look at B  D(*)0[KS]K sample by Belle
M2(KS+) [GeV2]
B  D*0 K 
M2(KS+) [GeV2]
hep-ex/0406067
Marcello A. Giorgi
A.Bozek, CP-4
13
BABAR analysis of B  D(*)0[KS]K
 [deg]
68% 90%
New for ICHEP04
D0 K 
D*0 K 
BABAR
D0 K 
rB
rB
 [deg]
rB  0.17 (90% CL)
rB*  0.23 (90% CL)
rB*
[No sensitivity to rB < 0.1]
d B  (130  45  8  10( model ) )o
d B*  (311  52  23  10( model ) )o
  (88  41  19  10( model ) )o
D*0 K 
BABAR CONF-04/043
ICHEP04August 20, 2004
rB*
Marcello A. Giorgi
Poor constraints on  as yet
G.Cavoto, CP-4
14
sin2 from B  , , 
but: “penguin”
is sizeable!
Interference of suppressed
b  u “tree” decay with mixing
B0 mixing
B0 decay: penguin
B0 decay: tree
d
b

d

b
q / p  Vtb*Vtd VtbVtd
A  Vub* Vud  3
q A
λ 
 ei 2  ei 2  ei 2
p A
A  Vtd*Vtb  3
 i id
T

Pe
e
i 2
λ  e
T  Pei eid
Coefficients of time-dependent CP Asymmetry
With no penguins
ICHEP04August 20, 2004
S  sin 2
C  0
With large penguins
and |P/T| ~ 0.3
Marcello A. Giorgi
2
S  1  C
sin 2 eff
C  sin d
15
Results for sin2eff from B   decays
BABAR: Updated for ICHEP04
BABAR
B    (227M pairs)
0


S  0.30  0.17  0.03
C  0.09  0.15  0.04
Belle: PRL 93 (2004) 021601
S  1.00  0.21  0.07
C  0.58  0.15  0.07
152M pairs
BABAR CONF-04/047, 04/035
Comparison
B    0 (227M pairs)
Caution
averaging!
A  0  0.01  0.10  0.02
BF  0  (5.8  0.6  0.4) 106
ICHEP04August 20, 2004
Marcello A. Giorgi
M.Cristinziani, CP-5
16
Updated for ICHEP04
Result for B  00
Fit  qq bkgd + B0    0  signal
Improved understanding of 0 efficiency:
 data /  MC  0.99  0.03 vs 0.88  0.08
N ( 0 0 )
BABAR
BB pairs
Run 1-3
122M
44±13
Run 4
105M
17±11
Run 1-4
227M
61±17
Consistent at 1.3s level
ICHEP04August 20, 2004
BABAR CONF-04/035
BF 0 0  (1.17  0.32  0.10) 10 6 4.9s
First
C 0 0  0.12  0.56  0.06 measurements
 -  eff  35o at 90% CL
BF 0 0  (2.32 0.41 0.22) 106 6.0s
0.48 0.18
First

0.16
C 0 0  0.43  0.51
0.17 measurements
Marcello A. Giorgi
M.Cristinziani, CP-4; Y.Chao, CP-6
17
Results for sin2eff from B   decays
Extraction of  similar to , but with advantage of smaller Penguin pollution:
| A00 | | A00 |
,
much smaller:    eff smaller
| A0 | | A |
Potentially     could be mixed CP,
but is observed to be almost pure CP  1
BABAR
Moriond QCD04
B 0      (122M BB pairs)
Signal: 314  34 events
flong  1.00  0.02
Slong  0.19  0.33  0.11
Clong  0.23  0.24  0.14
hep-ex / 0404029 to
B BPRL (89M BB pairs)
Slong  0.42  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)
BABAR
BF ( B    )  (22.5 5.7  5.8) 106
5.4

B0   0  0

0
Updated for ICHEP04
BABAR CONF-04/037
Updated result from Run 1-4 (227M BB pairs)
BF ( B 0   0  0 )  1.1106 (90% CL)
A
A
2 2d
A00 2
peng
o
A00
  96  10( stat )  4( sys )  11( peng ) 
A0  A0
Geometric limit on 2dpeng: Grossman-Quinn bound
ICHEP04August 20, 2004
Marcello A. Giorgi
Compare with 35o for 
C.Dallapiccola, CP-6
19
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 S 
using interference between
amplitudes
• Amplitude A3 dominated by
, , 00 and radial
excitations
• Form time-dependent decay
rate coefficients of
cos(mdt) and sin(mdt)
on this basis

ICHEP04August 20, 2004
Marcello A. Giorgi
S
20
Results from Dalitz analysis of B0  ()0
Evidence for
direct CP: 2.9s
Belle [152M]
BABAR [213M]
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 3.6s

ACP

A
BABAR
BABAR

A
  (102  11  15)o
[Based on factorization &
SU(3); Gronau & Zupan]
 [degrees]
ICHEP04August 20, 2004
hep-ex/0408003
Marcello A. Giorgi
27  6)o
  (113 
17
BABAR CONF-04/038
M.Cristinziani, CP-5; A.Somov, CP-621
Summary of constraints on 
BABAR & Belle
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
sin2βWA 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 bsss or bsdd gives the
same e2i as in tree process bccs. However loops can also be sensitive to New Physics!
b
W
u,c , t
B0
g
d
B
0
s  , ,( KK )
CP
s
s 0
K
d S
W
b
b
u,c , t
g
d
ICHEP04August 20, 2004
s K0
d S
d
d
0
B0
d
s
s
 , ,( KK )CP
s
0
K
d S
New phases from SUSY?
b
s
d
d
d
d
B0
Marcello A. Giorgi
K S0
0
25
BABAR results for B0  K0
2004 = 227M BB pairs (2003 = 120M pairs)
2003 result
CP  S K 0  0.47  0.34 0.08
0.06
C K 0  0.10  0.33  0.10
BABAR
K S0
Update for ICHEP04
B 0   K S0
114  12 events
S K 0  0.29  0.31
S
K
B 0   K L0
0
L
98  18 events
S K 0  1.05  0.51
L

CP  S K 0  0.50  0.25 0.07
0.04
C K 0  0.00  0.23  0.05
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
B 0  ( K  K  )CP K S0 (208M pairs)
BABAR
• Independent sample with (KK) mass
outside  region
• CP content can be determined experimentally
with an angular moment analysis through the
helicity angle distribution
Signal: 481  29 events
f even  0.89  0.08  0.04
S KKK 0  0.42  0.17  0.04
S
 ( 2 f even  1  S KKK 0  0.55  0.22  0.04  0.11
S
CKKK 0  0.10  0.14  0.06
S
ICHEP04August 20, 2004
Marcello A. Giorgi
A.Hoecker, CP-4
27
More BABAR results from b  sss penguins
CONF 04/040
CONF 04/019
Updates for
ICHEP04
208M BB pairs
     , 
   ,   0
K S0     , 0 0
0
BABAR
BABAR


ICHEP04August 20, 2004
B 0   K S0 Signal: 819  38
B 0  f 0 K S0
CP  SK 0  0.27  0.14  0.03
S
CK 0  0.21  0.10  0.03
CP  S f K 0  0.95 0.32  0.10
0.23
0 S
C f K 0  0.24  0.31  0.15
 sin 2  [cc ]@3.0s
S
Marcello A. Giorgi
0
Signal: 152  19
S
A.Hoecker, CP-4
28
Still another penguin mode: B0  0KS
Beam
y
constraint
B0
e  ( 4S  B 0
x


K

e  0
0
S
BABAR technique from 2003
Updated for ICHEP04
BABAR
BABAR CONF-04/030
227M BB pairs
Btag
Signal: 192 w/vertex, 108 w/o
CP  S 0 K 0  0.35 0.30  0.04
0.33
S
C 0 K 0  0.06  0.18  0.06
[sPlots: Pivk,
Le Diberder,
physics/0402083]
S
Belle
274M 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
BABAR
S
ICHEP04August 20, 2004
Marcello A. Giorgi
A.Hoecker, CP-4; C.F. Chen, CP-3
29
Results on sin2 from s-penguin modes
All new!
All new!
2.7s from s-penguin to sin2 (cc)
ICHEP04August 20, 2004
Marcello A. Giorgi
2.4s from s-penguin to sin2 (cc)
30
Projections for Penguin Modes
0.40
f0KS
KS0
jKS
’KS
KKKS
0.30
0.25
0.20
Luminosity
expectations:
2004=240 fb-1
2009=1.5 ab-1
K*
0.15
Similar projections
for Belle as well
0.10
5s discovery region if non-SM physics is 20% effect
Jan-09
Jul-08
Jan-08
Jul-07
Jan-07
Jul-06
Jan-06
Jul-05
Jan-04
Jul-03
Jan-03
2009
Jan-05
2004
0.00
Jul-09
0.05
Jul-04
Error on sine amplitude
0.35
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 bccs (new sin2 value
from charmonium 0.726 ± 037)
• Good agreement between BaBar and Belle results on bsss penguin, but both
experiments still show discrepancies (2.7 and 2.4s) 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 (1  2i )2
i
s (S f ) 
CP
1
N  QT
Tagging performance
QT=30.5% (6 categories) from
full Neural Network including
these & other physics processes
to identify b quark state
perfect resolution
B0 ( B 0 ) tag
smeared resolution
B0 ( B 0 ) tag
t resolution dominated
by tag side:
s(t)  1 ps  170 m
B  1.6 ps  250 m
CP asymmetry
ICHEP04August 20, 2004
Marcello A. Giorgi
35
cos2 from B0 → J/K*0(KS0)
• J/K*0 (KS0) 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 id ||, A0 =| A0 | e id 0)
and CP odd (A =| A | e id )
• Many terms in time-dependent decay rate, but two are proportional to cos2β
cos 2   2.72  0.50  0.027
0.79
BBAABBAR
AR
(with sin(2β) 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
cos 2   0.68 excluded
cos 2    1  sin 2 
at 86% CL
d (d S  d 0 )
0
dmK
Assuming:
2
ICHEP04August 20, 2004
Marcello A. Giorgi
○ solution 1: unphysical solution
● solution 2: physical solution
○ LASS data
36
Dalitz analysis of B  D(*)0[KS]K

For B : | A | | f (m , m )  rbe
m
2

2
2

2

i (d  )
m
D0
2

2

2
f (m , m ) |
2

m2  M ( K S0  ) 2
m2  M ( K S0  ) 2
D0
Schematic
view of the
interference
 rb ei ( d )
A 
2
m2
2
m2
For B  : | A |2 | f (m2 , m2 )  rb ei (d  ) f (m2 , m2 ) |2
Two-fold ambiguity remains in extraction of  (     )
ICHEP04August 20, 2004
Marcello A. Giorgi
37