Reaching for ?

1
Andrey Golutvin ITEP/Moscow
Reaching for ? (present and future)
2
This talk
V ud Vub
? arg
-V cd Vcb
3
There are a few methods of determining ?
CP violation in Interference of Mixing Decay
CP violation in Decay

• Rates and asymmetries in K? Decays
• Amplitude triangles for B? ?Dcp0K?
• (GLW method)
• extensions/modifications

• Time dependent asymmetries
• in Bd???- and Bs?KK- decays
• assuming U-spin symmetry
• Time dependent flavor tagged
• analysis of
• Bs?DsK- decay
• Bd?D? decay

4
Data Samples (present and future)
Results presented today are based on 81.2
fb-1(BaBar) and 78 fb-1(BELLE) That corresponds
to 88 and 85 mln BB pairs (part of data
sample) Statistics available today at
B-factories ? 300 mln BB pairs
-
-
-
In 2006 one expects ? 1.2 bln BB pairs
-
In 2008 after 1 year of LHCb (and BTeV) operation
? 1012 bb pairs Super
Bd-factory 1.5 to 5 bln of clean BB events
depending on achieved luminosity

-
5
g from B ? K? decays
K?
Significant interference of tree and penguin
amplitudes
Expect potentially large CP asymmetries
QCD penguins play the dominant role

• Difficulties
• Theoretical
• EW penguins
• SU(3) breaking (FSI) effects
• Experimental
• small BF, qq background
• Particle ID is crucial

Measurement of the ratios of BF and ACP may
provide constraints on ? and strong phase ?
dir
_
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Summary of BFs 10-6
From J.D. Olsen talk at the CKM workshop 2003
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Comparison of BF
No sign of rescattering yet
Present precision is dominated by statistical
errors In a few years statistical and
systematical errors should become comparable
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A Specific Model QCD Factorization
Beneke et. al., Nucl. Phys. B606, 245 (2001)
Data (2001)
Inconsistent?
Data (2003)
Data start to constrain models
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CP asymmetries
(allows one to eliminate dependence on the strong
phase ?)
Largest deviations 2s each in Kp-(BaBar),
rp-(BaBar), and Kp0(Belle)
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• In a few years statistical precision in the
  measurements
• of Branching Fractions (B?K?/??) should reach the
  level
• of systematic error, 2-4 depending on decay mode
• Extraction of ? will be dominated by
  theoretical
• uncertainties

BaBar K0? 80 fb-1
In 1 year BTeV expects 4600 K0? events (with
S/B 1) 62100 K-? events (with S/B20)
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Amplitude triangles
GLW method
B- ? DCPK- where DCP(1/?2)(D0? D0 )
A(B- ? DCPK-) ? A(B- ?D0K- ) A(B- ?D0K-
)ei?ei? A(B- ? DCPK) ? A(B- ?D0K ) A(B-
?D0K )e-i?ei?
CP-even states KK-, ??- CP-odd states
Ks?0, Ks?, Ks?, Ks?, Ks?
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? can be extracted from the reconstruction of
two triangles
Experimental problems A(B-?D0K-) is small
squashed triangles DCSD lead to the
common final states for D0 and D0 (color
suppressed A is of the same order as color
favored ? DCSD)
Experimental observables
BF(B-?D1,2K-)
BF(B-?D1,2?-)
/
, A1 and A2
R1,2
BF(B-?D0K-)
BF(B-?D0?-)
/
allow, in principle, to extract RDK- , ? and ?
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BaBar reconstructed D1K-
KK-
(7.4?1.7?0.6)
R1
(8.31?0.35?0.20)
0.09
AD1K- 0.17?0.23
-0.07
D1K-and
D2K-
BELLE studied both
R1 1.21 ? 0.25 ? 0.14 R2 1.41 ? 0.27 ?
0.15 AD1K- 0.06 ? 0.19 ? 0.04 AD2K- -0.18 ?
0.17 ? 0.05
No constraints on ? possible with this statistics

Needed significantly higher statistics
precision measurements of D Branching
Fractions
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B0?D0K()0 Mode
Two comparable color-suppressed amplitudes
Triangles are not as squashed as in B?? DK? case
_
_
1.3
BELLE
BF(B0? D0 K0) (5.0 ?0.6) ? 10-5
-1.2
_
_
1.1
BF(B0? D0 K0) (4.8 ?0.6) ? 10-5
-1.0
Hope to see soon B0? D0 K0 decay Present Upper
Limit is BF(B0? D0 K0) ? 1.8 ? 10-5
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ADS variant of the amplitude triangle approach
B- ? D0?fi K- and B- ? D0?fiK-, fi
K-? or K-??0 Use large interference
effects Experimentally challenging since BF of
O(10-7) are involved

Dalitz plot analysis of D ? KS? ?- for B-?DK-
and B?DK decays KS??- receives
contributions from B-? D0K-
D0?K-? K-? KS?- B-? D0K-
D0?K?- K? KS? B-? D0K-
D0?KS?0 ?0 ? ??- B-? D0K-
D0?KS?0 ?0 ? ??- Enough information to
extract ? for any magnitude of ?
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B0?D?- Mode
_
u
c
D-
?
_
favored
suppressed
d
d
_
_
c
b
b
u
_
B0
?
B0
D-
_
_
d
d
d
d
Suppressed/favored lt 10-2
Small CP-violating effect expected
Time evolution ?(B?D?) ? (1RD?2) ?
(1-RD?2)cos(?mt) ? 2 RD?sin(2??) sin(?mt)
(2? ?) is extracted from the measurement of 4
time-dependent asymmetries
RD? can be estimated using BF(B0?Ds?-)
BF(B0?Ds?-) ?
fDs2
BF(B0?D-?)
RD?2
?
?
fD2
tan2?c
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Evidence for B0?Ds?-
Br(B0?Ds?-)?Br(Ds???)
BaBar (1.13 ? 0.33 ? 0.21)x10-6 BELLE
(0.86 ? 0.11) x10-6
0.37
-0.30
BELLE have measured Br(Ds???)(3.72?0.39
) x10-6 using full/partial reconstruction
method
0.47
-0.39
RD? ? 0.022 ? 0.007
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D?- Data Samples (partial reconstruction)
?20 fb-1, 6970 240 events ?B0 1.510 0.040
0.041 ps
?30 fb-1 , 3430 80 events ?m 0.509 0.017
0.020 ps-1
?(sin(2??)) ? ? 0.15 for 1000 fb-1 T. Gershon
(CKM workshop, 2003) or ?(2??) ? 10o
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g from Bs ? D-s K , Ds K-
Same principle as for B0?D?- Since ?? is small ?
sensitivity should not depend on the value of ?
Two decay modes with comparable amplitudes, ? ?
10-4 each
? can be determined from the measurement of 4
time-dependent asymmetries (assuming that
?? is fixed from Bs mixing)
Contribution from NP is unlikely !
Looks as most clean method to measure ?
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Bs ? Dsp, DsK kinematics at LHCb
72k Ds? ?? 8k Ds? K?

• ? 6.5 MeV/c2

s 168 mm
s 418 mm
Bs vtx resolution (mm)
Ds mass (GeV)
Ds vtx resolution (mm)
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Importance of Particle ID

• Needed
• Hadronic trigger
• K/p separation
• Good proper time resolution

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In one year of LHCb running 8k
Bs?Ds?K? reconstructed events
Sensitivity slightly depends on strong phase
difference ?(T1/T2) and xs

• Assumptions
• 3k tagged Bs?DsK-
• 30 background
• 30 mistag

LHCb ?(?) ? 10º for xs 15 ?(?) ? 12º for xs
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BTeV ?(?) ? 8º
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g from B(s)? p p, K K proposed by R. Fleischer
Measure time-dependent asymmetries in B0 ? ??-
and Bs ? K K- decays to extract ?
where d?exp(i?) is a function of T and P
amplitudes
Assuming U-spin flavor symmetry dd and ?? ?
can be extracted
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g from B(s)? p p, K K
input values

• Evaluation of and
  sensitivity
• from time-dependent measured asymmetry

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In one year of LHCb operation
B0 ? ? ?-
?(A dir ) ? ?(A mix ) ? 0.054
BS ? K K-
?(A dir ) ? ?(A mix ) ? 0.043
Sensitivity to ? assuming 4 years of data
taking (4x27k Bd??? and 4x35k Bs?KK) B/S 0.8
and 0.55 correspondingly tagging ?D2 6.4
Combining all information ?(?) 2.50
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Conclusions
? can be measured both using CPV in decay
(time-integrated) and in the interference of
mixing and decay (time-dependent)
Only trees
(1) Theoretically clean b? c X
Amplitude triangles Bs?DsK
Trees loops
(2) Experimentally easier b ? hh (h non-c)
Experimental precision on BF already
below 10 level Clear theoretical
strategy how to extract ? is still missing
Measurement of rare decays with BF ? 10-7could
help
Sensitive probe for New Physics
(1) vs (2)
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Expectations from CDF Run IIa
ACPACP(dir)cos(?m?t) ACP(mix)sin(?m?t)
??/K?/KK/?K separation Inv. mass 20
MeV/c2 Kinematical variables dE/dX ?Md ltlt ?Ms
RunIIa ?ACP(dir, mix)0.2 (Bd???)
0.1 (Bs?KK)
?(?) 10?(stat)