Rare Hadronic B decays

1
Rare Hadronic B decays
Selected results from Babar, Belle, Cleo
2
Outline

• Introduction
• Analysis method
• Bu and Bd decays to mesonic final states
• (results and discussions)
• Conclusion

3
Introduction (1)

• Rare B decays
• branching fractions (BF) less than 10-5
• do not involve CKM favoured b-gtc transitions

• Theoretical mechanism
• CKM suppressed tree b-gtu transitions (T)
• loop (penguin) b-gts or b-gtd transitions (P)
• interference between T and P gt direct CP
  violation

Direct CP violation observable
weak phase diff. strong phase diff.
ACP sizeable when
and
4
Introduction (2)
Physics interest

• Standard Model
• Precise tests of the theoretical predictions
• (small amplitude processes)
• Potential evidence for CP violation
• Constraints on CKM parameters extraction of UT
  angles through

• direct measurements of the time-dependent
  asymmetries
• branching fraction dependence on the UT angles

• New Physics
• New particles hidden in the loops
• Constraints on theoretical models

SM
non-SM Higgs
SUSY
Observables

• BF
• time-integrated CP asymmetry
• time-dependent CP asymmetry

Covered in this talk
BFs and ACP (time-integrated) (Babar, Belle,
Cleo)
5
Analysis method
Babar, Belle, Cleo

• exploit production at threshold and small energy
  released in

Signal isolation

• identification of reconstructed B with 2 almost
  uncorrelated kinematical var.

beam-energy substituted mass (beam constrained
mass Mbc )
Signal mES mB
energy difference
Signal ?E 0
Background suppression

• continuum events - non-resonant

• event shape variables used
• independently, in a Fisher
• discriminant or in a Neural Network

B decays spheric
Continuum jet-like

• other B decays decay angles, helicity angles
  etc.

Signal extraction

• 1dim. or multidim. fit of ?E, mES(Mbc), shape
  var., PID var.
• cont. bkg. - modeled with a phase-space function
  with kinematical threshold
• - studied with events of
  sidebands in ?E, mES(Mbc) outside the signal
  region
• off-resonance data, MC
  etc.

6
Wealth of rare hadronic B decays!
Presented in this talk

• In this talk
• used HFAG averages
• rely on HFAG references
• referenced explicitly only new results

HFAG Heavy Flavor Averaging Group http//www.sla
c.stanford.edu/xorg/hfag
7
B -gt h h' ( h,h'K,
)
p
Physics interest

• provide information used in CKM angles ? (?2)
  and ? (?3)
• determination
• extraction of angles suffers from hadronic
• uncertainties in the theoretical calculations
• BFs give limits of these hadronic uncertainties
• ACP used to establish the direct CP violation in
  SM
• or indicate New Physics

8

B -gt
(1)
p
p
B -gt???-
b-gtu tree dominated
???-
78fb-1
82fb-1
signal
B -gt???0
b-gtu tree dominated
BF (10-6)
15fb-1
B -gt??0?0
4.2?
140fb-1
3.4?
142fb-1

• contributions from color-suppressed
• tree and gluonic penguin amplitudes
• theoretical predictions BF lt 110-6
• observation of significant signal

9
B -gt
(2)
p
p
BFs ratios
PR D65, 013004, 2002

• expectations
• significant penguin contribution
• to ??- mode gt penguin pollution
• complicates the extraction of ? (?2)
• from time-dependent CP asymmetries

CP Asymmetries
Preliminary
82fb-1
140fb-1
Direct CP violation in B0 -gt ? ?-
Obsevation
(in time-dependent analysis)
Do not observe CP violation
140fb-1
PRL, hep-ex/0401029
(time-dependent analysis)
Cross check time-integrated
asymmetry
10
B -gt
K
(1)
p

• b-gtu tree and b-gts penguin transitions
• penguin amplitude dominates

82fb-1
B -gt?K?

• no b-gtu transition, only b-gts penguin trans.
• good case to determine penguins contrib.

B -gt?K0?
B -gt?K0?0

• dominated by color suppressed tree

BF (10-6)
82fb-1
78fb-1
15fb-1
Significant penguin contribution
isospin relations the 3 ratios 1
11
B -gt
K
(2) and
K
K
B -gt
p
CP Asymmetries
B -gt?K?

• could be significant due to interference between
  T and P amplitudes

Preliminary

• no evidence of direct CP violation in K? decay
  modes

B -gt?KK BFs

• give information about the rescattering
  processes (FSI)
• rescattering can modify BF and ACP for ? ? and
  K? modes
• KK more sensitive to rescattering effects

82fb-1
BF (10-6)
140fb-1
9.13fb-1

• BF limits in agreement with pQCD predictions (PR
  D63, 014003 (2000))
• no evidence of rescattering yet

12
B -gt(
)(K,K
, )
h,h
r,p
Physics interest

• provide information for understanding the
  relative contribution
• of tree and penguin amplitudes in B decays
• have potential for establishing the direct CP
  violation

13
B -gt(
)(K,K
)
h,h
destructive interference and ?/? mixing
PL B254(1991)247
flavor-singlet (important for ?K)
CKM suppressed
agreement with NLO QCD
NP B651(2003)225
ACP expected (20-40) for the suppressed modes
K0, K0 modes - no external tree
BF (10-6)
Preliminary
Belle -0.02?0.07?0.01 Cleo 0.03?0.12?0.02
14
B -gt(
)(
)
h,h
r,p
CKM suppressed

• Expectations
• BFs (0.1-1.0) 10-6
• (?()? the highest)
• ACP large for ??,
• small for ??

color suppressed
hep-ph/0307395
ACP
dominant
?0, ?0 modes - no external tree
BF (10-6)
Preliminary
15
B -gt h ( h K,
)
r
p
Physics interest

• provide methods for extracting CKM angle ? ( ?2
  )
• e.g. decay amplitude isospin analysis of
• decay amplitudes are extracted from BFs and ACP
  asymmetries
• test the theoretical models with the BFs ratio
  
• (large range of predictions)

16
B-gt
0 0
r
p

• needed for the isospin analysis for ?extraction
• using the decay modes
• give limits on the contribution of penguin ampl.
  
• BF predictions around or below 10-6

signal
cont. B bkg.
cont. bkg.
140fb-1
hep-ex/0405068
Nsig15.1?4.8 Sig. 3.5?
Evidence
BF(5.1?1.6?0.9)10-6

• BF higher than the theoretical predictions
• central value higher than BaBar limit

82fb-1
BF lt 2.910-6
Some contributions to the decay ampl. higher
than expected gt isospin analysis more
complicated
17
B-gt h (hK,
)
r
p
BF (10-6)
82fb-1
140 / 78fb-1
9.1fb-1
Theory
BFs ratio
Babar

• R ? 6 tree level estimates
• Z. Phys. C34, 103 (1987)
• R ? 2-3 penguin, off-shell B
• Excited states, scalar ??- resonan.
• PRL 86,216 (2001), PR D66,034019(2002)

Acp
no evidence of direct CP violation
18
B-gt
(h,h,w,f)(h,h,w,f)


Physics interest

• test of theoretical models many different
  approaches
• search for New Physics signature

• suppressed amplitudes gt BF 10-6 or even less
  (e.g. BF(B-gt??)10-9)

• model independent bound on

PRD 68, 015004 (2003)
S timedependent CP asymmetry parameter
calculated with BFs of
If the experimental ?S much higher than this
bound gt New
Physics
19

B-gt
(h,h,w,f)(h,h,w,f)


Sign.
Babar 82fb-1
Cleo 3.1fb-1
hep-ex/0403046 Submited to PRL
With the new BF values
HFAG average
Scharmonium 0.736?0.049 S?Ks
0.27?0.21
B0 -gt ??
20


B-gtVV (V K, )
F,r
Physics interest

• angular distribution reflects strong and weak
  interaction dynamics
• aditional observables for detecting direct CP
  violation or NP

fL?L/ ? - longitudinal polarization fraction

• ?? modes provides an alternative method for ?
  measurement

21


rr, rK, FK
B-gt
B-gt?K - pure b-gts P (unambiguous signiture for
P)
B-gt?K - dominant b-gts P b-gtu tree
B-gt?? - b-gtu Tree and CKM suppressed b-gtd
P (potential ? measurement)
BF (10-6)
9fb-1
78fb-1
82fb-1
ACP
82fb-1
78fb-1
ACP expectations
?K 1 in SM, lt30 with NP
contribution ?K possible large (TP
interf.) ??0 isospin-breaking processes (e.g.
EW P)gt high CP asym.
22


rr, rK, FK
B-gt
Polarization
Theory predictions longitudinal polarization
dominates in all modes Measurements - helicity
angular distribution analysis -
full 3-dim. angular analysis (? K0 - Babar,
Belle)
fL
82fb-1
78fb-1
Less than expected!!
As expected
As expected
B-gt?K NP in b-gts penguin transition?
(hep-ph/0310229)
23
Conclusions

• observation of B-gt?0?0 BF (1.9?0.5) ?10-6
  (HFAG)
• observation of direct CP violation in B-gt ??-
  (Belle)
• no other evidence of direct CP violation
• time-integrated CP asymmetries (Babar)
• need more data to establish a conclusion
• evidence for B-gt?0?0 , Sig. 3.5? (Belle)
• BF higher than theoretical predictions
• 
  (Babar)
• B-gt?? fL? 1 expected (Babar and Belle)
• B-gt?K fLltlt1 not expected (Babar and
  Belle)

time-integrated
B factories are living interesting times.
More interesting ones will come!