Matter-Antimatter Asymmetries and
CKM Parameters in BABAR
Jeffrey D. Richman
University of California, Santa Barbara
Representing the BABAR collaboration
Meeting of the Particle Physics Program Prioritization Panel (P5)
Oct. 6, 2005
Version 3.0
Outline

Where are we in B physics?

A high-precision, benchmark measurement: sin2b from BJ/y K0

a: a work in progress

A path to g

|Vcb|, |Vub|, heavy-quark masses, and QCD parameters

Perspective and conclusions
• Zoltan Ligeti (theory):
•
•
discussion of theoretical issues &
uncertainties; new physics
Luca Silvestrini (theory): new physics sensitivity
Riccardo Faccini: BABAR measurements related to new physics and
rare decays, including sin2b from bs penguin modes
Exclusive B decays
CLEO (1983)
Long B lifetime
MAC, Mark II (1983)
B0B0 oscillations
ARGUS (1987)
BXu l n and Vub
ARGUS, CLEO (1990)
Observation of BK* g
CLEO II (1993): Loops!
BD* l n and Vcb
ARGUS, CLEO, LEP, Isgur,
Wise +…(>1989): HQET!
The Current Era in B Physics
Dramatic advances in our knowledge of the CP-violating
phase structure of quark interactions.

First achievement: clear and unmistakable evidence for large
(order unity) CP violation in the B meson system.

Amazing stream of surprising results and new methods. Many of
these would not have appeared in an extrapolation from the past.

Detector technology: can search for essentially any type of B
decay. Trigger on all events; Tracking/Vertexing + CsI + PID
Some notable or surprising measurements:
B  
B0     
B 0   K S0
0
0
0
B  J /y ( K  )s, p wave
0
0
S
0
B   ( D 0  K S0   ) K 
B 0  K *0g  K S0 0g
B    n  (limit)
B0  nn (limit)
cc  Ds (2317) X
e  e   g ISRY (4.26)
Probing the CKM quark mixing matrix
B0 ( B 0 )      ,  ,  + B  Xu n
a (2 )
B  n
*
ub
VudV
*
tb
VtdV
b
g (3 )
B   D0 / D0  K 
 D /D
0
0

CP
K

(GLW)
 K  K  
(ADS)
 ( K S0   ) K 
(Dalitz)
VcdV
*
cb
B 0 B 0 oscillation rate
Bs0 Bs0 oscillation rate
B0   0g
B0 ( B 0 )   cc  KS0
(1 )
B0 ( B 0 )   ss  KS0
B 0 ( B 0 )  (ccdd )
B  Xc n
B  D* n
• Angles of triangle: measure from CP asymmetries in B decay
• Sides of triangle: measure rates for buln, B0B0 mixing
• Other constraints in , plane from CP violation in K decay
CP asymmetry from interference between mixing and decay
AfCP (t ) 
  B 0 (t )  f CP     B 0 (t )  f CP 
  B 0 (t )  f CP     B 0 (t )  f CP 
AfCP (t )  S  sin( m  t ) - C  cos( m  t )
S

2  Im( )
1 
2
C
1 
2
1 
2
0
f CP H B
M  
q Af

 
0
M 12  12 f CP H B
p Af
*
12
*
12
i
2
i
2
1 decay amplitude, |q/p|=1:
  1  S  Im    , C  0
Af (t )  Im( )  sin( m  t )
CP
 /   1
 0.008  0.037  0.018
BABAR, PRD 70, 012007 (2004)
q
 1.0013  0.0034
p
HFAG
1 decay amp:
magnitude &
strong phase
divide out!
sin2b as a precision measurement
J /y , y (2 S ),  c1, c
B
0
K 0  K S0 , K L0
*0
0 0
K  K S
The ccs sin2b determination belongs to a special class of definitive
measurements in particle physics.
1. We can achieve high statistical precision before we are
limited by systematic uncertainties.
2. It is a data-driven measurement, with very little dependence
on Monte Carlo or theoretical assumptions.
3. Theoretical uncertainties <1%, so its interpretation is clear
(and powerful) [Ligeti, Silvestrini]
BABAR sin2b from charmonium (227 M BB)
(cc) KS (CP odd) modes
J/ψ KL (CP even) mode
asymmetry is opposite!
sin2b = 0.722  0.040 (stat)  0.023 (sys)
PRL 94, 161803 (2005),
(hep-ex/0408127)
|| = 0.950 +/- 0.031 (stat) +/- 0.013 (sys) hypothesis test
(after raw asymmetry shown above is corrected for the dilution)
Foundations of the sin2b measurement
e
e
B ( t )  (cc ) K
0
0
S
B 0 decay (tag)
0
S
1.6 ps  1/4 mm
t < 0
t resolution function
B ( t )  (cc ) K
0
t > 0
Mistag rates= w(tag)
Background
Mixing asymmetry
log scale
D  1  2w
t
Si detector alignment,
beam spot
t
MES (GeV)
Signal: 7,730 events (all modes)
Control: 72,878 events [D(*) ,,a1,J/yK*]
t=trec-ttag fits to BFlav control sample
Mixed
events
linear scale
t  trec  ttag (ps)
Unmixed
events
linear scale
Mixed
events
log scale
Unmixed
events
log scale
Mistag (w) measurement from BFlav oscillation data
 t /  B


e

fUnmixed ( t )  
1  1  2 w  cos  md  t     R( t )
Mixed


 4 B

m  0.502 ps-1
(fixed to PDG'04)
D=(1-2w)<1 due to mistags
T=2/m
B=1.6 ps
NoMix(t )  Mix(t )
Amix (t ) 
NoMix(t )  Mix(t )
Separately
determine D
for each tag
category.
Overall tagging
performance:
  (74.9  0.2)%
Q   (1  2 w)2
=(30.5  0.4)%
Systematic Errors for sin(2b)
s(sin2b)
s(sin2b) at
226 BB
1 ab-1 (est.)
Background shape & CP content of peaking
background
0.012
0.004 to 0.006
Mistag differences between BCP and Bflav samples
0.007
0.003
Composition and content of J/y KL background
0.011
0.005 to 0.009
t resolution and detector effects:
silicon detector alignment and t resolution model
0.011
0.004 to 0.008
Beam spot position
0.007
0.004 to 0.007
Fixed md, B, /, ||
0.005
0.002
Tag-side interference DCSD decays
0.003
0.003
MC statistics, bias
0.003
0.001
TOTAL
0.023
0.01 to 0.016
Category
Some systematics scale with 1/sqrt(N); other partially do.
sin2b uncertainties vs. integrated luminosity
Current
systematic
uncertainty
Range of
estimated
systematic
error: 1 ab-1
(109)
At 1 ab-1, we can improve sin2b by nearly a factor of 2.
a: A work in progress
Original idea for measuring a:
Works if B0+- amplitude is dominated by the bu tree process.
 
 
S   
q A  
    i 2 b  i 2g
i 2a
 
 CP e e
e
p A  
2  Im     
1    
2
=sin2a
If penguins were negligible,
we could extract a directly
from the time-dependent CP
asymmetry for B0+- with
no additional information.
C
B
0
b
d
1    
2
1    
2
W
Vub
0
u

d
u
d



The penguin problem in B0 (B0 ) 
• In 1998, CLEO performed a search for charmless two-body B
decays. Did not observe B0+- , but found large B0K+- rate
[CLEO, PRL 80, 3456 (1998)].
• We cannot ignore penguin amplitude in B0+-. (In fact, P-T
interference produces direct CP violation in B0K+- and may also
in B0+-).
b
B
Vub
u
u
0
d
d

d

Vtd ,...
b
d
d
u
d u

AfCP (t )  S  sin( m  t ) - C  cos( m  t )
S  1  C 2 sin 2 a  a  
C 0


We still measure S
and C, but S isn’t
sin2a!
I-spin solution to the penguin problem
[Gronau & London, PRL, 65, 3381 (1990)]
Use I-spin invariance of hadronic matrix elements to relate B
amplitudes. Assume that pions are identical particles.
A( B     0 ) 
A( B    ) 


0
1
2
1
2
A( B0     )  A( B0   0 0 )
triangle
relations
A( B    )  A( B    )
0


0
0
0
Penguins: I=1/2 only, so no contribution to B++0 .
b
B

u
d

u 
0
u
u

d
0

d
u d 
b
amplitudes cancel
u
0 
1
uu  dd 

2
Constraining a with I-spin relations
B++0 is pure tree (no gluonic penguin)triangles have common
side after rescaling one set by exp(2ig):
A( B     0 )  A( B     0 )  e2ig A( B     0 )
2a
1
A
2
1
A
2
A00
A0  A0
Grossman & Quinn,
PRD 58, 017504 (1998)
• If penguin amp=0,
triangles coincide.
4-fold discrete
A00 • ambiguity
(can flip
both triangles)
• take worst case as
“penguin error”
B( B0   0 0 )  B( B 0   0 0 )
sin a 
B( B     0 )  B( B     0 )
2
Measurements of B000, B0, and B++0
Mode
B/10-6 (BABAR)
B 0   0 0
1.17  0.32  0.10
B     0
B 0    
5.8  0.6  0.4
5.0  1.2  0.5
5.5  0.4  0.3
4.4  0.6  0.3
C 0 0
0.12  0.56  0.06
B 0   0 0
B/10-6 (Belle)
 0.2
2.30.4
0.5 0.3
00 amp.
isn’t small
compared to
the others.
a  35
(90% C.L.)
BABAR PRL 94,
181802 (2005)
BABAR
Red triangles: B+ and B0 decays
Purple triangles: B- and B0 decays
Difference: CP violating interference
between T and P amplitudes.
Huge program on B decays to charmless hadronic final states...
Bigger
than 
B( B 0   0  0 )
 1.1  106
BABAR, PRL 94, 131801 (2005)
(10-6)
The investigation of B
BABAR has made intensive effort to study the B modes:
• Measurement of B++0 , B0 00 limit [PRL 91, 171802 (2003).]
• 1st observation of B+- and polarization measurement
[PRD 69, 031102 (2004)]
• First time-dependent CP asymmetry measurement and
confirmation of polarization. [PRL 93, 231801 (2005)]
• Updated time-dependent CP asymmetry measurement with
Run 1-4 data. [hep-ex/0503049 PRL]
• Limit on B000 branching fraction [PRL 94, 131801 (2005)]
Mode
B0   0  0
B     0
B0     
a   14
B/10-6 (BABAR)
B/10-6 (Belle)
 1.1 (90% C.L.) [230 M BB ]
2365  6
[89 M BB ]
32  7 47
30  4  5
[89 BB ]
24.4  2.23.8
4.1 [275 M BB ]
(90% C.L.)
(compare with 35 for B     )
[85 M BB ]
BABAR, PRL 94,
131801 (2005)
Measurement of CP asymmetry for B
Is the  system in a CP eigenstate?
If not, get effective dilution of CP
asymmetry.





B
0

232 M
BB̅

0
B0 tags
Angular analysis 
almost pure CP=+1 !
BABAR
fL
B0 tags

  0, 1
0
BABAR, PRL 95, 041805 (2005)
BELLE (LP2005)
0.033 0.029
0.978  0.014 00..021
029 0.951 0.039 0.031
S
 0.33  0.24 00..08
14
C
 0.03  0.18  0.09 0.00  0.3000..0910
0.09  0.42  0.08
t (ps)
Would like to see S, C with 5x data!
a: combining the BABAR measurements
B 
PRL, 94, 181802 (2005)
B 
PRL 95, 041805 (2005)
α = 100º  13º
1s
[29º;61º] excluded @ 90% C.L.
79º< α <123º @ 90% C.L
a (deg)
1-C.L.
B 0 Dalitz
hep-ex/
0408089
a  11327
17 ( stat )  6 ( sys ) 

a  103

10 
 9
CKM fit
excluding a
measurements
a (deg)
a (deg)
Projections for a measurement in B+Current a measurement
from B
1s
90% C.L.
+1s
B(B00)
unchanged
-1s
Multiple unresolved
solutions within each
peak.
Projected a measurements
from B for 1 ab-1
The uncertainty on a depends
critically on B(B00).
Scenarios:
1. use current central value
2. +1s
3. - 1s
Critical issue for a measurement: B00
I-spin triangle for B
(current measurements)
Projected 1s uncertainties on a
Projected 2s uncertainties on a
Goals and issues for the a program
B
Resolve issues with S and C: Belle observes significant direct CP violation
in B; BABAR doesn’t.
BABAR and Belle values of B00 are higher than theoretical
expectations (and differ by x2) and are not precisely measured.
B
Complicated Dalitz-plot measurement; currently disfavors one of the
solution regions allowed from B. Will this hold up with more data?
B
Need to observe B00. Value is critical in constraining the I-spin
triangle and determinining penguin-induced uncertainty on a.
Is I-spin conserved? Does the triangle close?
Non-resonant background: studies indicate is small effect but more data
would allow more detailed investigation.
Improve measurements of S and C…also investigate Ba1+
A path to g
A( B   D 0 K  )  AB rB ei (d g )
A( B   D 0 K  )  AB
u
V 
*
us
b
u
Vcb  A
s
c
K

color suppressed
b Vub  e
 ig
2
u
D0
u
Vcs*  1
u
0
c D
su

K
How can we get interference? Need D0 f and D0 f. (Compare
with B0J/y K0.) Some observations:
1. Uses charged B decays; method is based on a direct CP asymmetry.
Issues: strong phase d, rB=|A(bu)/A(bc)| =0.1-0.2
2. Uses tree diagrams: no loops/mixing diagrams, no penguin/new
physics issues. Together with |Vub|, gives CKM test with trees only.
g (GLW method): B-DCPK-, DCPfCP
D0 (D0 ) fCP = CP eigenstate from singly-Cabibbo-suppressed decay.
[Gronau & London, PLB 253, 483 (1991), Gronau & Wyler, PLB 265, 172 (1991)].
D
c
u
0
W
Vcd

*
ud
V
d
u
d
u


Vud d


D
c
u
0
W
Vcd*
u
d
u




CP  1  +  , K  K 
CP  1 K S0 0 , K S0 , K S0, K S0 , K S0 
Amp  B  , CPD0  D   AB 1  D rB ei (d B g ) 
Large rate, but
interference is
small: rB << 1
g (ADS method): B-  [ D0K+ -; D0K+ -]KAtwood, Dunietz, & Soni, PRL 78, 3257 (1997),
PRD 63, 036005 (2001)
B  D0 K  ; D0  K  
u
K
s
B
c
b
u
u
DCSD
c
D
0
u
B  D0 K  ; D0  K  
B

Vub
e  ig
b
u
A  B  , D  K 
u
c
su
D0
K
D0
c
u
CFD
s
K
u
d
u

d

u
s
u
K
 A A
B

id D
i ( d B g )


r
e

r
e
D  D
B
Interference is large: rB, rD comparable, but overall rate is small!
g (Dalitz plot): B-  [ D0Ks  - ; D0 Ks  - ]K-,
m2  m 2 ( K S0  )2
Giri, Grossman, Soffer, & Zupan, PRD 68, 054018 (2003),
Bondar (Belle), PRD 70, 072003 (2004)


B
M  (m2 , m2 )  A( B   D 0 K  ) f (m2 , m2 )  rB eid B e ig f (m2 , m2 )
B
M  (m2 , m2 )  A( B   D 0 K  )  f (m2 , m2 )  rBeid B e  ig f (m2 , m2 ) 
m2
|M|2 =
D
m2
0
D
2
0
 rB ei (d B g )
m2
m2
Relatively large BFs; all charged tracks; only 2-fold g ambiguity.
Interference depends on Dalitz region: f  K S0  0 (CP), f  K *  (DCSD)
Fitting the D0KS+- Dalitz plot
BABAR hep-ex/0504039
CA
K*(892)
Use continuum data
D*+D0+ (91.5 fb-1)
Nevts = 82 K
Purity: 97%
m2  m 2 ( K S0  )
m2  m 2 ( K S0  )
(770)
DCS K*(892)
Issue: contribution of
broad, s-wave resonances
(1) Orig. method: 2 BWs
(2) New: K-matrix
Anisovich & Saratev
Eur. Phys. J A16, 229 (2003)
2/dof3824/3022=1.27
B+/D0K+/: KS +- Dalitz plot distributions
B+D0K+
B+D0K+
Differences between B+ and B signifies direct CP violation.
Good S/B, but needs more data.
BD0K
BD0K
Above, D0 is superposition of D0 and D0
g: BABAR and Belle results (Dalitz method)
BABAR (+stat+sys+model)
Belle (+stat+sys+model)
hep-ex/04110439, 0504013
hep-ex/0504039, 0507101
rB (D0K)
0.12  0.08  0.03  0.04
0.21  0.08  0.03  0.04
rB (D*0K)
0.17  0.10  0.03  0.03
0.120.16
0.11  0.02  0.04
rB (D0K*)
 0.50 (0.75) @ 1s (2s )
0.25  0.18  0.09  0.04  0.08
g
(67  28  13  11)
direct CP
significance
2.4s
non-K*
(68  15  13  11)
2.3s
s (g )
Importance of rB …
(degrees)
0.1
0.2
rB
The error on g is very sensitive
to the value of rB. Other methods
(ADS, GLW) help us to measure
rB .
rB measurements from ADS channels
Most measurements using interference with DCSD D0 decay
indicate rB<0.2.
Projected uncertainty on g for rB = 0.1
Projected sys
error due to
D0 Dalitz plot
We will be able to improve the error on g by at least a factor of 2.
Surprises in semileptonic B decays

Vcb , Vub
b
B
n
c, u
bc:
*
**
D, D , D ,...
bu:
 ,  , ,  , , a1,...
• Two complementary experimental and theoretical approaches
 Exclusive decays: measure (and predict) the rate for specific
exclusive modes, usually in restricted region of phase space.
 Inclusive decays: use as much of phase space as possible to
minimize theoretical input. Extract non-perturbative QCD
parameters from data. Goal: |Vij| (exclusive) = |Vij| (inclusive)!
|Vcb| and the atomic physics of B mesons
Extract |Vcb |, quark masses, and non-perturbative QCD parameters
from measured inclusive lepton-energy spectrum and hadron recoil
mass spectrum (masses, QCD params given below: “kinetic scheme”).
r  mc* / mb
Yields |Vcb | to about 2%. (lattice QCD goal: 3% for BD
ln)
GF2 mb5
2
 SL ( B  X cln ) 
V
(1  Aew ) Apert ( r,  )
cb
3
192
3


 D3   LS
2
2
kinetic

   G  m
expectation
b
  z0 ( r )  1 
2
value
2mb






BABAR, PRL 93, 011803 (2004)
chromomagnetic
expec value


  2(1  r )



Darwin term
spin-orbit
3
3
   LS
G2  D
 D3
mb
4
mb2


4
 d ( r ) 3  O (1/ mb ) 
mb



Benson, Bigi, Mannel & Uraltsev, hep-ph/0410080
Gambino & Uraltsev, Eur.Phys.J. C34, 181 (2004)
Vcb  (41.4  0.4 exp  0.4 HQE  0.6 th )  10 3
2  (0.45  0.04 exp  0.04 HQE  0.01a ) GeV 2
Bc n  (10.61  0.16exp  0.06 HQE )%
G2  (0.27  0.06exp  0.03HQE  0.02a ) GeV 2
s
s
mb  (4.61  0.05exp  0.04 HQE  0.02as ) GeV
 D3  (0.20  0.02 exp  0.02 HQE  0.00a ) GeV 3
mc  (1.18  0.07exp  0.06 HQE  0.02as ) GeV
3
 LS
 ( 0.09  0.04 exp  0.07 HQE  0.01a ) GeV 3
s
s
Why measuring |Vub | is hard
Vub
Vcb
( B  X u n )
0.1 
( B  X c n )
2%
Lepton spectrum endpoint analysis
BABAR
Large bc background; suppression cuts
introduce dependence on theory
predictions for kinematic distributions.
Fully reconstructed B recoil analysis

(hep-ex/0509040)
e-
continuum data (off res)
Xu
BABAR
bc subtraction
bu
D*
Breco
e+
n
l
Brecoil
|Vub |: inclusive measurements
• Key CKM constraint
Vub
  2 2  
Vcb
• Use mb and QCD
parameters extracted from
inclusive BXc l n and
BXs g spectra.
• Many methods with
uncertainties around 10%.
• Uncertainty from mb has
been reduced to 4.5%.
• With more data, the |Vub|
uncertainties could be
pushed down to 5%-6.5%.
Eℓ endpoint
Eℓ vs. q2
mX
mX vs. q2
Vub WAvg  (4.38  0.19  0.27)  10 3
expt mb, theory
Measuring |Vub| using B l n and lattice QCD
2
q 2  qmin

n
q
u
2
q 2  qmax

u

n
q
B0 l- n form-factor predictions
f+(q2) is relevant
form factor for
B l n l=e, 
Fermilab/MILC
HPQCD
restricted q2 range
q
At fixed q2, lepton
momentum spectrum is
exactly known in this
mode, since only one
form factor.
2
HPQCD: hep-lat/0408019
Fermilab/MILC: hep-lat/0409116
Experiment vs. Lattice: DK l n form factor
Measuring |Vub| using B l n
BABAR
PRD 72, 051102 (2005)
Projection to 1 ab-1 (data taken to be on
BK fit curve from present measurement).
In the high q2 region alone, we will measure the branching fraction
with an uncertainty of (6-7)% , or (3-3.5)% uncertainty on |Vub |. Lattice
theorists expect to reach 6%, so exclusive/inclusive will be similar.
Perspective/Conclusions
Four major measurement programs related to determining the values
of fundamental Standard Model CKM parameters.
Parameter
sin2b
1
a
2
g
3
|Vub |
Goals for 1 ab-1
Methods
Measure sin2b to +/- 0.025 or
bettter.
t-dependent CP asymmetry
measurements; t resolution and
mistags measured in data
Understand B, B, B
decays. Measure a to 8-16 degrees
(depends on B00).
t-dependent CP asymmetry
measurements + isospin analysis of
related modes; B appears to be the
most powerful.
Understand B+D K+ decays;
measure g to 9 degrees or better
(depends on rB).
Direct CP (t-independent) measurement;
determine strong phases & relative
amplitudes from data. D0 Dalitz-plot
analysis+(D0CP) +(D0DCSD); also
measure sin(2b+g.
Understand inclusive BXc l n,
inclusive BXu l n, and B l n;
measure |Vub| to 6.5% or better.
Inclusive: determine heavy-quark
parameters from kinematic distributions;
Exclusive: ln at high q2 + lattice QCD.
Perspective/Conclusions
Many measurements are now multidimensional: extract not only the
quantity of interest, but also critical information that is difficult
to get from theory. Examples:
• a and g measurements are data-driven: isospin triangle, rB, etc.
• b-quark mass and other QCD parameters are now well
determined from Vcb studies; this information is used as input for
the Vub measurement.
CKM measurements go hand-in-hand with other parts of the BABAR
physics program:
• Enormous program of hadronic rare B decay studies
• Search for departures from CKM pattern using bs decays
• Studies of electroweak penguin and leptonic decays
• Charm physics, including searches for mixing and CP violation.
These are great ideas and measurements: this is a great physics program!
Backup slides
CP Asymmetries: formulas and definitions
0
fCP
B ( bd )
no net oscillation
no net oscillation
B
0
net oscillation
fCP
B0 ( bd )
B
0
( Bphys (t )  fCP )
B
0
net oscillation
0
( B

f  (t )  exp(t ) cosh    t   2 Re(λ f )  sinh    t 
 2 
 2 


1  λf
2
1  λf
2
0
phys
B
0
(t )  fCP )
 cos( m  t ) 
2 Im(λ f )
1  λf
2


 sin( m  t ) 


For / <<1,


f  (t )  exp(t ) 1


1  λf
2
1  λf
2
cos( m  t )

2 Im(λ f )
1  λf
2


 sin( m  t ) 


Behavior of time-dependent CP asymmetries
Linear
scale
Log scale
Non-exponential
decay law for a
specific final
state!
Angles of the unitarity triangle
Consider two complex numbers z1 and z2.
z1  z1 ei1
z2  z2 e
i 2

 VtdVtb* 
a  arg  
* 
 VudVub 
 VcdVcb* 
b  arg  
* 
V
V
 td tb 
 VudVub* 
g  arg 
* 
 VcdVcb 
z2 / z2
 ei (2 1 )
z1 / z1
*
ub
 z2 
arg    2  1
 z1 
a
VtdVtb*
VudV
b
g
VcdV
*
cb
The CKM matrix and its mysterious pattern
(Wolfenstein parametrization)
1  12 

Vud Vus Vub  

V

1 2
V
V



1

cs
cb 
2

 cd
V
  A 3 (1    i )  A 2
V
V
ts
tb 
 td

 0.97 0.23 0.004 
 0.23 0.97 0.04 


 0.004 0.04

1


2
A 3 (   i ) 

2
4
A

O
(

)


1

(magnitudes only)
• The SM offers no explanation for this numerical pattern.
• But SM framework is highly predictive:
 Unitarity triangle: (Col 1)(Col 3)* =0 etc.
 Only 4 independent parameters: A, , , 
 One independent CP-violating phase parameter
Comments on B physics history (see slide 3)

Exclusive B decays: Reconstruction of bc modes requires charm meson
reconstruction. The product branching fractions for BD(*)X, D(*)K(n
modes are typically of the order 10-4 to 10-5, so large data samples are
needed. The 1st exclusive B signal from CLEO was made by summing over
several different modes.

Long B lifetime: showed that Vcb was smaller than expected. We began to
see the larger pattern of the CKM matrix outside the 2x2 Cabibbo sector:
Vcb is proportional to 2 , not . This measurement also demonstrated the
critical importance of high-precision tracking and provided a strong
impetus to the development of Si vertex detectors.

BB oscillations: this critical discovery was made by ARGUS. The
oscillation period is about 12.6 ps (6.3 ps for maximal probability to
oscillate), which is about 8x larger than the mean decay time of 1.6 ps. CP
violation in mixing is a very small effect in B decays, since the off-shell
intermediate states such as tt completely dominate over on-shell
intermediate states. CP violation requires interference between these two
paths. This simplifies the BABAR/Belle CP violation measurements, which
are based on a different effect: the interference between mixing and decay
amplitudes.
Comments on B physics history (see slide 3)

Observation of charmless semileptonic B decays by ARGUS and CLEO
was a critical discovery. The measured value of Vub/Vcb maps out an
annular region in the  plane. The consistency between this region and
the BB mixing and K regions provided an early test of the CKM
framework. In the Vub measurement, the lepton spectrum endpoint region
was used, because backgrounds from bcln decays are suppressed
compared with buln, where the lepton can be more energetic. Later
measurements use a variety of techniques to increase the phase space
region used and to thereby decrease theoretical uncertainties.

The observation of BK*g by CLEO was a major discovery,
demonstrating the presence of loop processes at the rate expected in the
SM. BABAR/Belle are studying a very large number loop processes in both
exclusive and inclusive measurements. These processes provide a powerful
probe of physics beyond the SM through virtual effects.

Vcb measurements were given a strong boost by the development of Heavy
Quark Effective Theory (HQET). This and subsequent theoretical
advances have substantially improved our understanding of the dynamics
of B decays.
A simplified picture of the CKM matrix
Largest phases in the Wolfenstein
parametrization
Magnitudes of CKM elements
d
u
c
t
1

3
s

1
2
b
-iγ
3
2
1
1
 1 1 e 


 1 1 1 
 e-iβ 1 1 


Note: all terms in the inner product between columns 1 and 3 are
of order 3. This produces a unitarity triangle of roughly equal sides.
sin2b measurement: signal modes
signal region
yield
yield
signal region
MES (GeV)
MES (GeV)
yield
signal region
BABAR
J/ψ KL signal
J/ψ X background
Non-J/ψ background
ΔE (MeV)
CP sample
J/ψ KS (KS→π+π-)
J/ψ KS (KS→π0π0)
ψ(2S) KS (KS→π+π-)
χc1 KS (KS→π+π-)
ηc KS (KS→π+π-)
Total for ηCP=-1
J/ψ K*0(K*0→ KSπ0)
J/ψ KL
Total
NTAG
2751
653
485
194
287
4370
572
2788
7730
purity
96%
88%
87%
85%
74%
92%
77%
56%
78%
ηCP
-1
-1
-1
-1
-1
-1
+0.51
+1
Control samples for sin2b
Use neutral B control sample (“BFlav”) to determine tagging dilution
and t resolution parameters from simultaneous fit to the data.
MES (GeV)
MES (GeV)
BFlav sample
NTAG
purity
D- / +/a1+ (6 decay modes)
32974
83.1%
D*- π+/ρ+/a1+ (12 decay modes)
35008
89.4%
J/ψ K*0(K*0→ K+π-) (2 modes)
4896
95.8%
Total
72878
Tagging algorithm performance
(%)
w(%)
w(%)
Q(%)
Lepton
8.6+/-0.1
3.2+/-0.4
0.2+/-0.8
7.5+/-0.2
KaonI
10.9+/-0.1
4.6+/-0.5
0.7+/-0.9
9.0+/-0.2
KaonII
17.1+/-0.1
15.6+/-0.5
0.7+/-0.8
8.1+/-0.2
K-
13.7+/-0.1
23.7+/-0.6
0.4+/-1.0
3.8+/-0.2

14.5+/-0.1
33.9+/-0.6
5.1+/-1.0
1.7+/-0.1
Other
10.0+/-0.1
41.1+/-0.8
2.4+/-1.2
0.3+/-0.1
Total
74.9+/-0.2
Measure of tagging
performance Q:
Q=(1-2w)2
30.5+/-0.4
1
s (sin 2 b ) 
Q
Lepton category not
sensitive to mistag
differences due to
DCSD decays
New Belle result (summer 2005)
J/ψ KS (CP odd) mode
Belle-CONF-0569
hep-ex/0507037
J/ψ KL (CP even) mode
386 M
BB
sin(21 )  0.652  0.039  0.020
C  0.010  0.026  0.036
BABAR and Belle Systematic Errors
(for aficionados)
BABAR,
bccs modes
only
Belle,
bccs
and
bsss
modes
sin2b results from charmonium: summary
from Kazuo Abe’s talk at LP05
backup slide
backup slide
BABAR and Belle time-dependent CP
asymmetry results for B0
Belle observes significant direct CP violation in B0+-.
BABAR-Belle: 2.3s
Asymmetry for direct CP violation
A  A1 e
i (1 d1 )
A  ( A1 e
Asymmetry 
 A2 e
i ( 1 d1 )
2
2
2
2
A  A
A  A

i ( 2 d 2 )
 A2 e
i (  2 d 2 )
)e
 i ( P )  ( f )
2sin(1   2 )sin(d1  d 2 )
2
2
A2
A2

 2 cos(1   2 ) cos(d1  d 2 )
A1
A1
Problems with interpreting measurements of direct CP asymmetries:
1. We often don’t know the difference d1-d2 , so we cannot
extract 1-2 from the asymmetry without additional information.
2. We often don’t know the relative magnitude of the interfering
amplitudes.
a short digression…
Direct CP violation in B0K-/B0K+
The tree-penguin interference that is bothering us in B0
shows up spectacularly as direct CP violation in B0K+.
Bkgd symmetric!
n  B 0  K     910
n  B 0  K     696
696  910
A
 0.133
696  910
AK  0.133  0.030  0.009
N ( BB )  227  106
B( B  K )  2  105
a: direct measurement vs. CKM fit
11
a [CKM fit]  (96-12
)
Combining , ,  measurements of a
a  (99 )
12
-9
B CP(t)
asymmetry
disfavors
 mirror solution
a inferred from
other CKM
measurements
Sensitivity to g across the Dalitz plot
Monte Carlo
g from BDK (all methods)
g meas   63

15 
12
g CKM   57713 
B-DCPK-, DCPfCP (GLW) Fit Results
GLW method: D decays to CP eigenstates
3 unknowns: g, d, rB
4 observables (3 independent relations)
Don’t yet observe significant asymmetries.
In principle can solve
for everything! (Just
need a lot of data.)
ADS method
Note: both the B and D diagrams are different now
 two strong phases (but they combine)
Two observables
4 unknowns: g, rB, rD, d=dB+dD
rD2 
B  D 0  K   
B  D 0  K   
 (3.9  0.6)  10
3
Need one more observable:
measure another D final
state: (same dB but different
dD. Now have: g, rB, dB+dD1,
dB+dD2
Basically a good method, but no significant signals yet!
B-DCPK-, DCPfCP (GLW) Fit Results
B l n
q2 distribution from
various experiments
Branching fraction
measurements, including
restricted q2 region.
The CKM Triangle Using Angles Only