Transcript Experiments on CP Violation in B Meson decay David Hitlin Matter and Antimatter: Fact and Fancy April 16, 2010 David Hitlin Quinn Symposium April 16, 2010

Experiments on
CP Violation in B Meson decay
David Hitlin
Matter and Antimatter: Fact and Fancy
April 16, 2010
David Hitlin
Quinn Symposium
April 16, 2010
1
The CP problem(s)
 CP violation in the strong interactions is weak, while
CP violation in the weak interactions is strong
 Helen Quinn has played a role in both these problems
 She has been a member of the
BABAR Collaboration since
(before) its inception
 Her insight has been brought to bear on a variety of important
problems concerning CP violation measurements, which I will
refer to as we proceed
 She also was co-editor of the
BABAR Physics Book, and
co-author of a mystery thriller
David Hitlin
Quinn Symposium
April 16, 2010
2
The CKM Matrix
 In 1973 Kobayashi and Maskawa realized that
extending Cabibbo’s two generation mixing matrix
that relates the quark mass eigenstates to the
weak eigenstates to a third generation introduced
a phase that could account for CP-violating
0
effects first seen in K L decay in 1964
 “Hadronic engineering” issues did not
allow a quantitative comparison of the phase in
theory and experiment
 Bigi and Sanda proposed that CP –violating
asymmetries in B0 decays to CP eigenstates could
be directly related to theoretical quantities
 In 2001 BABAR and Belle measured
the CP asymmetry in b® ccs decays,
showing that the CKM phase could account
for the observation and leading to the award of
the 2008 Nobel Prize to Kobayashi and Maskawa
David Hitlin
Quinn Symposium
 Vud Vus Vub 


V   Vcd Vcs Vcb 
V V V 
ts
tb 
 td
 d '
d 
 
 
 s' V  s 
 b'
b
 
 
April 16, 2010
3
The elevator speech (if the elevator is in the physics department)
 The Wolfenstein parametrization
 The Unitarity condition (1 of 6)
VCKM
V V V V V V  0
*
ud ub
*
cd cb
*
td tb
 1 2 / 2

A 3 (   i ) 


4


1 2 / 2
A 2

O
(

)

 A 3 (1    i )  A 2

1


 The “b” Unitarity Triangle
 The UT phases
 VtdVtb* 
 VcdVcb* 
  arg  
  arg  
* 
* 
 VudVub 
 VtdVtb 
 VudVub* 
 VtsVtb* 
g  arg  
 s  arg  
* 
* 
V
V
V
V
 cd cb 
 cs cb 
 NB :       g 
 CP-violating asymmetries in Bd, Bs decays can measure all the phases
 Combinations of tree level decay BRs can measure g
 Since any combination of three sides or angles determines a triangle,
we can perform a unique set of overconstrained tests of the
consistency of the CKM matrix
David Hitlin
Quinn Symposium
April 16, 2010
4
At the start of the “B Factory era”
Dib, Dunietz, Gilman and Nir - 1989
The mass of the top quark, required to sharpen UT tests, was unknown
David Hitlin
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April 16, 2010
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David Hitlin
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At the start of the “B Factory era”
David Hitlin
Quinn Symposium
Dib, Dunietz, Gilman and Nir - 1989
April 16, 2010
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Many measurements provide unitarity triangle constraints
Theoretical errors
are often pertinent
David Hitlin
Quinn Symposium
April 16, 2010
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To measure the CP asymmetry in decays to CP
eigenstates requires a time-dependent analysis
( B  fCP )  ( B  fCP )
ACP (t ) 
0
0
( B  fCP )  ( B  fCP )
0
0
 CP [ S sin  m t   C cos  m t ]
David Hitlin
2Im CP
S
2
1 | CP |
1 | CP | 2
C
1 | CP | 2
Quinn Symposium
CP  ei 2 
April 16, 2010
A( B 0  fCP )
A( B 0  fCP )
9
Here’s how:


J /y
0
Brec
U (4S )
-
e
e
K
+
0
S

Reconstruct exclusive B decays to
CP eigenstates and flavor eigenstates
and tag the flavor of the other B decay

Select BCP candidates
0
Btag
 z
K
( B 0  J / K S0 , etc.)
Select Btag events using, primarily,
and Bflav candidates
leptons and K's from B hadronic
decays & determine B flavor
(B
0
 D*- p + , etc.)
Measure the mistag fractions wi and determine the
dilutions Di = 1- 2 wi
Measure  z between BCP and Btag to determine the
signed time difference  t between the decays
Determine the resolution function for  z
i 3
fi
R(t ; aˆ )  
exp  (t   i ) 2  / 2 i2
i 1 
2
i
David Hitlin
Quinn Symposium
April 16, 2010
10
Global CKM Fit
 Consistency of angles
  89.0

4.4 o
4.2
   21.1  0.9 
o
g   75  12 
o
    g  185  13
o
 Consistency of angles and
sides from global fit
 Overall good fit (CKMFitter:
global p-value 45%)
 ~2σ tension between sin2β
and εK / Vub
 correction to εK will make fit
UTFit:   0.154  0.022
CKMFitter:   0.1390.025
0.027
  0.342  0.014
  0.3410.016
0.015
David Hitlin
Quinn Symposium
worse
Buras, Guadagnoli, PRD78, 033005
(2008)
April 16, 2010
11
sin2β from b  ccs
c J /
b
B
decays
c
0
s 0
d KS
d
*
tb td
*
tb td
V*td
b
B
d 0
s KS
c J /
c
t
0
d
V*td t
*
cb cs
*
cb cs
qA VV VV
2i
tree 

 (1)e
pA VV VV
David Hitlin
Quinn Symposium
April 16, 2010
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sin2β from b  ccs
decays
Theoretically clean measurement of |S| = sin2β with
B  J/ψ K0, J/ ψ K*, ψ(2SKS, cKS, & cc1KS by BABAR and Belle
SWA  0.672  0.023
CWA  0.004  0.019
BABAR, PRD 79,072009 (2009)
S  0.687  0.028  0.012
C  0.024  0.020  0.016
David Hitlin
  (21.1  0.9)
Quinn Symposium
statistically limited
April 16, 2010
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David Hitlin
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sin2 from b  uud decays
Vub
b
B
d
0
d
u   
u 

d
 
V*td
b
B
d
t
0
V*tdt
d  
u  
u  
 
d
ei 2 ei 2g  e2i
mixing decay
David Hitlin
Quinn Symposium
April 16, 2010
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sin2 from B0  
Two amplitudes (P/T ~ 0.3) :
b → u “tree”
b → d “penguin”
d
g
e
i 2 
e
i 2g
 e2i
PRL 98, 211801 (2007)
mixing decay
Sππ  sin2aeff = sin2(   )
S  0.61  0.10  0.04 (5.3 )
C  0.55  0.08  0.05 (5.5 )
S ,WA  0.65  0.07
C ,WA  0.38  0.06
Excluded
at 95% CL
Determine  from
isospin analysis
Gronau & London,
PRL 65, 3381 (1990)
David Hitlin
Quinn Symposium
April 16, 2010
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Ouch !
Gronau-London-Sinha2
Grossman-Quinn
David Hitlin
Quinn Symposium
April 16, 2010
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sin2 from B  , , 
 VV decay B  
 Separate isospin analysis for each
polarization amplitude
 Longitudinal polarization >90%
 Small penguin contribution in B → 
  0 0      ,     0







Br B     (24.2  3.2)  10

 0
6
Br B     (24.0  2.0)  10
Br B 0   0  0  (0.73  0.28) 106
0


6

S  0.05  0.17
C    0.06  0.13
PRL 102, 141802 (2009)
 =89.0
+4.4
4.2
David Hitlin
Quinn Symposium
April 16, 2010
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g

from B 

(*)
D K
Decays
 Rates of B±  D (*) K± decays are
sensitive to g through interference
of b  c and b  u transitions
( *)0
( *)0
 Need states accessible to D
and D
 Several neutral
D (*) final
states have
been studied by BABAR, Belle and CDF
 Must also determine
A(b  u)
rb 
A(b  c)
D decays:
GLW : CP eigenstates , KK, etc.)
s
B

b
Vcb
u
b
B
u
K
u
c
u
Vub
D0
u
0
D
c
s
u
K
3.4 σ
Gronau & London, PLB 253, 483 (1991);
Gronau & Wyler, PLB 265, 172 (1991)
ADS: Flavor DCSD states (K)
Atwood, Dunietz, & Soni, PRL 78, 3257 (1997),
Atwood, Dunietz, & Soni, PRD 63, 036005 (2001)
GGSZ: 3-body decays (KS, KSKK)
Giri, Grossman, Soffer, & Zupan, PRD 68, 054018 (2003)
Bondar, PRD 70, 072003 (2004)
New BABAR measurement with first
evidence for ADS signal in B- → DK-
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Quinn Symposium
Lopez-March @ EPS’09
April 16, 2010
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g from
B-

(*)
D K
 Interference in B 
Decays
decays with 3-body Dalitz
analysis of D  KSπ π, D  KSKK are sensitive to g
-
David Hitlin
(*)
D K
Quinn Symposium
April 16, 2010
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CKM Fitter results
as of Moriond 2010
Adding in the CP asymmetry
measurements from BABAR and
Belle,
we now have a set of highly
overconstrained tests, which
grosso modo, are well-satisfied
UTFit:   0.154  0.022
  0.342  0.014
David Hitlin
  89.0
CKMFitter:   0.139
0.025
0.027
  0.3410.016
0.015
Quinn Symposium

4.4 o
4.2
   21.1  0.9 
o
g   75  12 
o
    g  185  13
April 16, 2010
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o
A decade of progress
David Hitlin
Quinn Symposium
April 16, 2010
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 sufficient constraints to explore subsets
All
Angles only
David Hitlin
CP-violating
Tree amplitudes
Quinn Symposium
CP-conserving
Loop amplitudes
April 16, 2010
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Whither Heavy Flavor Physics ?
 Flavor physics provides the experimental foundation of much of the
Standard Model
 Heavy flavor physics plays an important role, in that it furnishes many
parameters that can be
 determined experimentally with precision
 compared with reliable theoretical predictions
 As such, heavy flavor physics has served
 to establish major pillars of the Standard Model:
 the particle content
 the weak couplings
 the suppression of flavor-changing neutral currents, ……
and
 to constrain what lies beyond the Standard Model
 When new physics is found at the LHC
 Flavor physics has provided, and will continue to provide,
unique information on the nature of any new physics found at LHC
David Hitlin
Quinn Symposium
April 16, 2010
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Can we learn more ?
 Unitarity triangle tests
 These primarily involve measurements in the B system, but require
measurements of the Cabibbo angle, eK and theoretical inputs
1. Does the agreement of the overconstrained tests stand up to detailed
scrutiny ?
2. Can the UT tests be improved with better theoretical calculations and/or
improved experiments ?
3. Is there any room for new physics ?
 There are a few issues
 Overconstrained tests of three generation unitarity
 Does the unitarity triangle close ?
 Are there extra mixing phases ?
 Are there extra CP-violating phases ?
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Quinn Symposium
April 16, 2010
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David Hitlin
Quinn Symposium
April 16, 2010
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The B(B→tn) conflict
2 2
2
2

G
f
m
m
m


F
t
B
B
 ( B  t n t ) 
1  2t
8
 mB

 Vub

2
Also constrains Higgs doublet models
G. Eigen
David Hitlin
Quinn Symposium
April 16, 2010
28
The K problem
 The four B→K decays provide four branching fraction measurements, four direct
CP asymmetries and one mixing-induced CP asymmetry (B0→K0 0)
 The decay amplitudes are related by isospin
A(B0  K   )  2 A(B  K  0 )  2 A(B0  K 0 0 )  A(B  K 0  )  0
 The amplitudes can be written in terms of tree and penguin Standard Model amplitudes
 A SM sum rule (Gronau-Rosner) relates the asymmetries
0 
 0
0 0
B
(
K

)
t
2
B
(
K

)
t
2
B
(
K
 )
 
0 
 0
0 0


A( K  )  A( K  )
 A( K  )
 A( K  )
 
 
B ( K  )t 0
B ( K  )t 0
B ( K   )
 Consistent with the SM at the 20% level
 New Physics:
C
1
2
PNP e
ifP
C ,u ifu
 A e
3
C
ifEW
C
EW , NP
P
e

C ,u ifuC
3
C , d ifdC
A e
C , d if CdC
A e A e
NP in PNPeifp  A(K00) = -0.15
NP in PCEW,NPeifEW  A(K00) = -0.03
 ACP  A(K   )  A(K  0 )
David Hitlin
Quinn Symposium
April 16, 2010
G. Eigen
29
βs from Bs → J/ψf decays
 SM predicts very small βs (~0.02)
 Thus sensitive to new physics in Bs mixing
 DØ and CDF measure βs with fit to decay
time and angular distribution of Bs → J/ψf
 Simultaneous fit to extract ΔΓs and βs
DØ and CDF working on updates with >2x samples
LHCb sensitivity with 0.5 fb-1: s  0.02
David Hitlin
Quinn Symposium
April 16, 2010
30
Does the agreement of the overconstrained tests
stand up to detailed scrutiny ?
 There is actually some tension,
Lunghi and Soni
and there are enough constraints
to explore these issues
 Caveats:
 There may be Standard Model
explanations for some effects
 All issues are at the <3 level
 Inclusive and exclusive Vub determinations are not in good agreement
 There are also issues with inclusive/exclusive Vcb
 The B(B→tn) conflict in Vub
 The Bs → ψϕ phase
 The K problem
 The agreement of the fitted, i.e., SM-predicted, value of sin 2 vs
the directly measured value using tree decays and loop decays is not
perfect
David Hitlin
Quinn Symposium
April 16, 2010
31
Is there a fourth quark generation ?
 A fourth generation CKM-like mixing matrix has
 2 additional quark masses
 3 additional mixing angles
 2 additional CP-violating phases
 A recent analysis by
Bobrowski, Lenz, Reidl and Rohrwild
(Phys.Rev.D79:113006,2009)
shows that large regions of the new
parameter spaces are still allowed
 SuperB will be the primary tool to close down,
or, perhaps find, non-zero values of these
fourth generation parameters
q24
14
q14
13
 Potential motivation (Hou): with 4 generations and mt', mb' ~300-600 GeV, gain 1013-1015 in the effect of
SM CP violation on the baryon asymmetry of the universe !
David Hitlin
Quinn Symposium
April 16, 2010
32
Correlations in CP asymmetries in rare decays are diagnostic of SM4 models
 SM4 models have been comprehensively explored by
Buras, Duling, Feldmann, Heidsieck, Promberger & Recksiegel (arXiv:1002.2126v2 [hep-ph])
 Many CKM extension patterns are possible in the mixing matrix
 For example, a 1, , 2, 3, 4 pattern for 0ff-diagonal terms leads to a “Wolfenstein”
parametrization:
=
 Many other VSM4 patterns are
There are also additional
effects in KL, Bd and Bs decays
David Hitlin
(%)
possible.
They can be identified, and
distinguished from SUSY
and extra dimension models,
by the observed patterns of
CP-violating effects:
Quinn Symposium
April 16, 2010
33
Okada, et al: a sample of new physics models
David Hitlin
Quinn Symposium
April 16, 2010
34
CPV Probes of New Physics
 In the Standard Model we expect the same value for “sin2 ” in
b  ccs, b  ccd , b  sss, b  dds modes, but different SUSY
models can produce different asymmetries
 Since the penguin modes have branching fractions one or two
orders of magnitude less than tree modes, a great deal of
luminosity is required to make these measurements to
meaningful precision
B0  J / KS0
B0  f KS0
q A Vtb*Vtd VtbVts*
2i
penguin 


(

1)
e
p A VtbVtd* Vtb*Vts
q A Vtb*Vtd VcbVcs*
2i
tree 


(

1)
e
p A VtbVtd* Vcb*Vcs
W-
b
u,c,t
c-
H-
s
b
u,c,t
i (2  f SUSY )
 e
David Hitlin
s
b
~ ~~
u,c,t
0
g,
~c
s
b
~ ~~
d,s,b
s
A
 Sf K  sin(2  f SUSY )
A
Quinn Symposium
April 16, 2010
35
 from b  s(qq) penguin loop decays
b
B
0
t
BABAR PRD 79, 052003 (2009)
B 0  ' KS0
s
467M BB
g
 In the SM the penguin decay
B0  ' KS0
amplitude is dominant and has same
weak phase as bqqs amplitude
 expect to measure |S| = sin(2)
 SM contributions from suppressed
diagrams expected to be small
(sin(2) = sin(2eff) sin(2) ~ 0.01-0.1)
 Penguin decays with b → sqq loop
sensitive to New Physics from heavy
particles
 New Physics contributions could
cause large  sin(2)
David Hitlin
Quinn Symposium
N  B0   N  B 0 
N  B0   N  B 0 
sin 2  eff  0.57 ± 0.08 ± 0.02
C  0.08 ± 0.06 ± 0.02
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sin2β from b  s(qq) penguin loop decays
 CP asymmetries have been
measured in 9 different
b  s (qq) modes by BABAR/Belle
 All measurements of sin2βeff are
Theoretically
clean modes
consistent with sin2βb→ccs
 C is consistent with zero
 Naïve average sin2βeff of all b → sqq
modes used to be ~3σ lower than
sin2β (~2004), now ~1σ
 Some modes (fK0, 'K0, K0K0K0)
have relatively small theoretical
uncertainties (~5%)
sin2eff ,clean  0.59  0.06
David Hitlin
Quinn Symposium
April 16, 2010
37
Gold
1) b  sss decays have 1-5% the rate of b  ccs decays
2) There are important penguin and tree corrections
b
 VtbVts* ~  2
W
t
g
Silver
Bronze
 VtbVts* ~  2
W
t
g
d
b
d
s
s
d
d
b
s
 VubVus* ~  4Rueig
W
u
s
b
s
g
d
s
d
f
K
0
f
K0
 VubVus* ~  4Rueig
s
s
s
d
 VtbVts* ~  2
W
t
s
d
g
d
d
u
b
 ', f0
d
W

K0
u
s
d
 ', f0
K
0
29
 VubVus* ~  4Rueig
 ,  ,
0
u
b
K0
0
d
W
u
s
d
 0 ,  0 ,
K
0
J /y KS0
David Hitlin
4
Quinn Symposium
April 16, 2010
20
Corrections
of up to 20%
corrections
for sin2β
are possible
These
corrections
can be
calculated
and/or
bounded
440 x10-6
38
Can we resolve these outstanding issues in heavy flavor physics?
 To access the very rare b, c and t decays that can show effects
due to a fourth generation, SUSY, extra dimensions, etc., requires
large hadronic data samples (viz. LHC) and an e+e- data sample
~100x as large as the total BABAR/Belle data set (~1.3 ab-1)
 As none of us is getting any younger, obtaining this sample in our
lifetime requires an asymmetric collider with a luminosity of 1036,
which can record 15 ab-1/New Snowmass Year, as well as a
detector that can cope with the event rates and backgrounds
BABAR
SuperB
David Hitlin
Quinn Symposium
April 16, 2010
39
Lepton Flavor Violation in t decays
Super B Factory sensitivity directly confronts New Physics models
SuperB
sensitivity
For 75 ab-1
We expect to see LFV events, not just improve limits
David Hitlin
Quinn Symposium
April 16, 2010
40
Polarized t’s can probe the chiral structure of LFV
in a model-independent manner
t
tt





A longitudinally polarized electron
beam, producing polarized t’s,
can determinate the chiral
structure of lepton flavor-violating
interactions
Dassinger, Feldmann, Mannel, and Turczyk
JHEP 0710:039,2007;
[See also Matsuzaki and Sanda
Phys.Rev.D77:073003,2008 ]
Also:
• Reduction in backgrounds for rare t decays
• Measurement of t anamolous magnetic moment
• Search for CP or T violation in t production and decay
David Hitlin
Quinn Symposium
April 16, 2010
41
Polarized t’s can probe the chiral structure of LFV
in a model-independent manner
t
tt





A longitudinally polarized electron
beam, producing polarized t’s,
can determinate the chiral
structure of lepton flavor-violating
interactions
Dassinger, Feldmann, Mannel, and Turczyk
JHEP 0710:039,2007;
[See also Matsuzaki and Sanda
Phys.Rev.D77:073003,2008 ]
Also:
• Reduction in backgrounds for rare t decays
• Measurement of t anamolous magnetic moment
• Search for CP or T violation in t production and decay
David Hitlin
Quinn Symposium
April 16, 2010
42
A DNA Chip for New Physics
Altmannshofer, Buras,
Gori, Paradis and Straub
Nucl.Phys.B830,
7-94, 2010
David Hitlin
Quinn Symposium
April 16, 2010
43
The National Research Plan
for 2010-2012 of the
Italian Ministry of
Education and Science
David Hitlin
Quinn Symposium
April 16, 2010
44
Conclusions


CP violation experiments have provided some of the key building
blocks for the construction of the three generation
Standard Model
Through a series of overconstrained tests the B factories have
convincingly shown that the CKM phase can account for a wide
variety of experimental phenomena, although there are still some
intriguing discrepancies
 This, of course, leaves us with the mystery of the origin of the
matter-antimatter asymmetry (leptogenesis ?)
 There is still room for a fourth generation, which could be
pertinent to the baryon symmetry problem
 SM extensions provide many additional CP-violating phases
 Super
B Factories, now hopefully near to becoming a reality,
can provide unique sensitivity to explore this area, and, more
generally, the flavor structure of any new physics found at the
LHC
David Hitlin
Quinn Symposium
April 16, 2010
45