# Presentation: 137403

##     and 

-     and 
-    at Babar
*Malcolm John*
*LPNHE – **Université**s Paris 6&7*
- On behalf of the *B**A**B**AR* collaboration

## PEP-II and BABAR have performed beyond expectation
CP violation in the B system is well established
sin(2) fast becoming a precision measurement

As for the other two angles (the subject of this presentation) :
Many analysis strategies in progress
The CKM angle  is measured but greater precision will come

First experimental results on  are available

First experimental results on 2 are available

Results presented here are based on datasets up-to 227 MBB
BABAR and PEP-II aim to achieve 550 MBB (500 fb1) by summer 2006

- CP violation in the B system is well established
- sin(2) fast becoming a precision measurement
- As for the other two angles (the subject of this presentation) :
- Many analysis strategies in progress
- The CKM angle  is measured but greater precision will come
- First experimental results on  are available
- First experimental results on 2 are available
- Results presented here are based on datasets up-to 227 M*BB*
*B**A**B**AR** *and PEP-II aim to achieve 550 M*BB* (500 fb1) by summer 2006

- Conclusions (for those who can't wait...)

## 

**(0,0)**

**(0,1)**

**(********,********)**

****

****

****

## BABAR : where? what? who?

*B**A**B**AR** *collaboration consists 11 countries and ~590 physicists !

**DIRC ****(PID)**
- 144 quartz bars
- 11000 PMs

**1.5T solenoid**

**E****lectro****M****agnetic**** C****alorimeter**
- 6580 CsI(Tl) crystals

**D****rift ****C****hamber**
- 40 layers

**I****nstrumented ****F****lux ****R****eturn**
- iron / RPCs  [ → LSTs ]

**S****ilicon ****V****ertex ****T****racker**
- 5 layers, double sided strips

- At the PEP-II *B*-factory at SLAC

- e+ (3.1 GeV)

- (9.0 GeV) e-

## PEP-II : performance

- PEP-II / *B**A**B**AR** *: August 2004
*L**peak* = 9.2×1033 cm2 s1
- (3 times design luminosity !)
- PEP-II delivered 	253 fb1
*B**A**B**AR** *recorded  	244 fb1
- At (4S) resonance	221 fb1
- Analysis dataset 	211 fb1

- Beams circulating in PEP-II again this month for the beginning of the 2005-2006 run.
- Aim for 500 fb1 by summer 2006
- Belle and KEKB are running well
- Their dataset could be 600 fb1 in the same time period

## Analysis techniques : Continuum suppression

- For every      pair-production, expect three
*Many techniques available it fight this background.*
*They can be amalgamated in linear discriminators or neural networks.*

## Analysis techniques : mES and E

- Precise kinematics, unique to machines operating at a threshold
- The initial energy of the system is well known from the precise tuning of the beam

## Large data sample feeds a plethora of analyses

- New particle searches : Pentaquarks, exotic baryons, *D**sJ*

- Tau physics : lifetime measurements, rare decay searches

- Charm physics : *D**0* mixing, precision *D**0* measurements

- New physics searches in s-penguin decays

- Precision measurement of SM CP violation : sin(2

- SM CP violation : measurement of CKM angle 

- SM CP violation : measurement of CKM angle 

- Search for rare leptonic *B* decays

- Semileptonic *B* decays and the determination of |*V**ub*| and |*V**cb*|

- Radiative penguin *B* decays

- Precision measurement of SM CP violation : sin(2

- SM CP violation : measurement of CKM angle 

- SM CP violation : measurement of CKM angle 

- SM CP violation : measurement of CKM angles 2

- SM CP violation : measurement of CKM angles 2

## Time-dependent analysis requires B0 flavour tagging

- Time-dependent analysis requires *B*0 flavour tagging

- We need to know the flavour of the *B* at a reference t=0.

***B****** 0***

-      tag

***B****** 0***

-         rec

***B****** 0***

- At t=0 we _know_ this meson is *B*0

## Formalism of CP violation with B mesons

*C*  0 : Direct *CP* violation

- Formalism of *CP* violation with *B* mesons

- Time evolution of a

*S*  0 : Indirect *CP* violation

- Time-dependent asymmetry

- from mixing

## 

*B* → *J*/ *K*S

## sin(2) measurement with charmonium (214 MBB)

- sin(2) measurement with charmonium (214 M*B**B*)

- Time-dependent asymmetry with an amplitude  sin(2)

- 7730 events

## 

*B* → 
*B* → 
*B* → 

## The route to sin

- Access to  from the interference of a *b*→*u* decay () with *B**0**B**0* mixing ()

- Inc. penguin contribution

- How can we obtain α from αeff ?

- Time-dep. asymmetry :

**

*NB :    T = "tree" amplitude      P = "penguin" amplitude*

## How to estimate |eff| : Isospin analysis

- Use SU(2) to relate decay rates of different *hh* final states (*h * {})
- Need to measure several related B.F.s

- Gronau, London : PRL**65**, 3381 (1990)

- Difficult to reconstruct.
- Limiting factor in analysis

- 2|*eff*|

## Time-dependent ACP of B→

- Time-dependent *A**CP *of *B*→

- Good /*K* separation up to 4.5 GeV/*c*

- Blue : Fit projection
- Red : *q**q * background + *B*0→*K* cross-feed

- BR result in fact obtained from 97M*B**B*

## Now we need B→

- Now we need *B*→

- Analysis method reconstructs and fits *B*→and *B*→*K*together

*B*→

*B*→*K*

- Inserts show background components

*B*→*h*

## ...and B→

- 61±17 events in signal peak (227M*BB*)
- Signal significance = 5.0
- Detection efficiency 25%

- Time-integrated result gives :

***B******±******→************±************0***

## Isospin analysis using B→

- Isospin analysis using *B→***

- Extraction of  follows the same logic as for the *B→****  *system
- Except  is a vector-vector state
-   is not generally a *CP* eigenstate
- Angular analysis needed

*Longitudinal*
*Helicity state h=0*
*CP+1 eigenstate*

*Transverse*
*Helicity state h=*±1
*non-CP eigenstate*

- However,                      is measured to be 1 in *B*→
- Transverse component taken as zero in analysis

## Time dependent analysis of B→

- Time dependent analysis of *B→*********

- Maximum likelihood fit in 8-D variable space

- 32133 events in fit sample

## Similar analysis used to search for  
Dominant systematic stems from the potential interference from B→a1±± (~22%)

- Dominant systematic stems from the potential interference from *B→a**1**±****± *(~22%)

- Searching for *B→*********

*c.f. B→*********
*B.F.= 4.7 *x *10****6*
*and B→*********
*B.F.= 1.2 *x *10****6*

*B *(*B→**********= 33 *x *10****6*

## Taking the world average
	and thanks to
	we apply the isospin analysis to B→ 
The small rate of                      means
|eff | is small[er]
P/T is small in the B→ system
(...Relative to B→ system)

- Taking the world average
- 	and thanks to
- 	we apply the isospin analysis to *B→***
- The small rate of                      means
*|****eff **| *is small[er]
- P/T is small in the *B→*** system
- (...Relative to *B→*** system)

- Isospin analysis using *B→***

*|****eff **|< 11°*

## Another approach : B→()0 

- Another approach : *B*→()0

- Unlike and , is not a CP eigenstate
- Must consider 4 (flavour/charge) configurations
- Equivalent "isospin analysis" not viable (triangles→pentagons, 6→12 unknowns...)
- However, a full time-dependent Dalitz plot analysis of                        can work!
- Enough information to constrain 

- Snyder, Quinn : PRD **48**, 2139 (1993)

- Interference at equal masses-squared gives information on strong phases between resonances

****

****

****

- 

****

****

****

****

****

## Time-dependent Dalitz fit 

- Extract  and strong phases using interferences between amplitudes
- Time evolution of                       can be written as :

- Assuming amplitude                                is dominated by , and , we write

- The "f"s are functions of the Dalitz-plot and describe the kinematics of *B*→(S→VS)
- The "A"s are the complex amplitudes containing weak and strong phases. They are independent of the Dalitz variables

*script {****} refers to {**************}*

- Complicated stuff!
- At least 17 parameters to fit-for in a 6-D variable space
- Large backgrounds. Over 80% of selected events are continuum

## B→ : data/MC, 213MBB

- Fit finds 1184 ± 58

- mES

- E’

- ’ (DP variable)

- m’ (DP variable)

- NN

- t

- Signal

- Self-crossfeed

- B-background

- Continuum-background

## Hint of direct CP-violation

- Fit result → Physics results : *B→*(**)*0** **  *213M*BB*

*Mirror solution not shown*
*Weak constraint at C.L.<5%*

- 2.9 

- Likelihood scan of using :

***{****}*
*T =tree amp. *
*P =penguin*

**

**

## Combining results on 

- Combining results in a global CKM fit
- Mirror solutions are clearly disfavoured
-   is measured.
- Although improve-ments will come

## 

*B**±* → *D*(*)*K*(*)
- GLW, ADS and
- D0-Dalitz methods

## How to access ?

- Decays where                              interferes with

- charged *B*s only (time-independent, direct CPV)
- no penguins pollution
- Need same final state

- Strong phase between diagrams

* **Crucial parameter :*
*(not well measured)*

## GLW method : B→D0K (214 MBB)

- GLW method : *B→D*0*K* (214 M*B**B*)

- Main background from kinematically similar *B→D**0***which has B.F. 12x larger
- So the signal and this main background are fitted together
- 2D fit to DE and the Čerenkov angle of the prompt track

- A 2 cut on C in these plots

*R**CP+ *= 0.87±0.14(stat.) ±0.06(syst.)

*R**CP**** *= 0.80±0.14(stat.) ±0.08(syst.)

*A**CP+ *= 0.40±0.15(stat.) ±0.08(syst.)

*A**CP**** *= 0.21±0.17(stat.) ±0.07(syst.)

*R**CP+ *=   1.73±0.36(stat.) ±0.11(syst.)

*R**CP**** *=   0.64±0.25(stat.) ±0.07(syst.)

*A**CP+ *= 0.08±0.20(stat.) ±0.06(syst.)

*A**CP**** *= 0.35±0.38(stat.) ±0.10(syst.)

*B**±**→D**0**K***±*

- Only a loose bound on *r**B* with current statistics: (*r**B*)*2* = 0.19±0.23

## Accessing  without using CP states

- Using CP final states of the *D**0* yields an expected A*CP* of only ~10%
- We can potentially do better using "wrong-sign" final states

- Colour     ** ****favoured** bc amplitude

- Colour** suppressed** bu amplitude

- And with enough events (*i.e.* large *r**B*), expect large asymmetry

*D**0**→K**** *suppression factor*: r**D* = 0.060±0.003
- Phys.Rev.Lett. 91:17 1801

## ADS method : B→D(*)0K (227 MBB)

- ADS method : *B→D*(*)0*K* (227 M*B**B*)

- The number of                                events depends foremost on the value of

## b→u sensitivity with an unsuppressed D0 decay 

- Consider once again *B→D*(*)0*K* decays, this time the with *D*0*→K**S****.*
- Obtain *D* information from a fit to the *D*0 Dalitz plot

***→ ******K******S*********

***→ ******K******S*********

*D*0 Dalitz model

## The D0→KSDalitz model

- Determine on clean, high statistics sample of 81500 *D**→*D*0 events
- ASSUME no *D*-mixing or *CP* violation in *D* decays
- Build model from 15 known resonances (+2 unidentified scalar  resonances)

********** ********d.o.f.** = 3824/(3054-32) = **1.27**

## D0 Dalitz method : B→D(*)0K (227 MBB)

- 282 ± 20

- 44 ± 8

- 89 ± 11

- Maximum likelihood fit extracts *r**B**(*****)** *,, (*) from a fit to *m**ES**, ****E, Fisher *and the *D*0→*K*S Dalitz model.

## Measurement of gamma
Twofold ambiguity in  extraction

- Twofold ambiguity in  extraction

*D*0 Dalitz method : *B→D*(*)0*K* : result

_*DK*_*  :     **r**B*   <  0.19

_*D*K*_* :   *  *r**B*  = 0.155

- (90% C.L.)

*+0.070*

***0.077*

- ± 0.040 ± 0.020

**   =  70°±26°±10°±10°    (+n)

***B*   =  114°±41°±8°±10°    (+n)

***B*  =  303°±34°±14°±10°    (+n)

- 68%

- 95%

- Bayesian C.L.s

- 3rd error is due attributed to the Dalitz model

## 

- 

- 

*B**0* → *D*(*)*K*(*)
*B**0* → *D**±**K**S*
*B**0* → *D*(*) 

## Other ways to access b→u  

- So, what happens if we start with a neutral *B*0?

- bc amplitude

- bu amplitude

- Eventually this will be a time-dependent analysis
- Early days yet though. Using non-*CP* modes of the *D*0, we search for :

***→ ******f******CP***

***→ ******f******CP***

- _AND_

- _AND_

## B0→D(*)0K(*)0 (124 MBB) 

*B*0→*D*(*)0*K*(*)0 (124 M*B**B*)

- Very challenging for 

## Avoiding colour suppression : B0→D±KS± (88 MBB) 

- bc amplitude

- bu amplitude

- Method has two advantages :
- Avoids colour suppression in *b*→*u*
- Integrating over Dalitz plane removes ambiguities in eventual  extraction
- First experimental step complete :
- Branching fraction measurement
- Currently, Too few events for TD analysis
- 1/3 of events are _NOT_ in the K* region

##  Another way to sinB0→D*

**favoured** bc amplitude

**suppressed** bu amplitude

- ~

- ~

- Both      and      decay to             , neither with a colour-suppressed diagram

- but there's is not enough information to solve the system...
- The suppression factor, *r**B* must be taken from elsewhere.

## B0→D*: very small ACP offset by copious statistics

- Full reconstruction (110M*B**B*)

- Partial reconstruction (178 M*B**B*)

- Total yields (all tags)

-                     yields

- D*
- Combinat. BB
- Peaking BB
- Continuum

- Find events with two pions and examine the missing mass ***X***

## sin results

- sin results

- Partial reconstruction (178 M*B**B*)

- Full reconstruction (110M*B**B*)

*L*

*L*

*L*

*L*

*L* : result uses lepton tags only

## PEP-II and BABAR have performed beyond expectation
CP violation in the B system is well established
sin(2) fast becoming a precision measurement

As for the other two angles (the subject of this presentation) :
Many analysis strategies in progress
The CKM angle  is measured but greater precision will come

First experimental results on  are available

First experimental results on 2 are available

Results presented here are based on datasets up-to 227 MBB
BABAR and PEP-II aim to achieve 550 MBB (500 fb1) by summer 2006

- CP violation in the B system is well established
- sin(2) fast becoming a precision measurement
- As for the other two angles (the subject of this presentation) :
- Many analysis strategies in progress
- The CKM angle  is measured but greater precision will come
- First experimental results on  are available
- First experimental results on 2 are available
- Results presented here are based on datasets up-to 227 M*BB*
*B**A**B**AR** *and PEP-II aim to achieve 550 M*BB* (500 fb1) by summer 2006

- Conclusions

## BACK-UP

*BACK-UP*

## PEP-II : performance

- 5Hz "trickle" injection used in 2004

## Comparison with Belle : CPV in B0  

- Belle report observation of CPV in *B**0** * 

- >3 discrepancy between *B**A**B**AR** *& Belle

**Belle 3.2******** evidence for Direct *****CP***** violation **_**not supported**_** by ***B**A**B**AR** ***measurements**

## GLW method : B→D0K* (227 MBB)

- GLW method : *B→D*0*K** (227 M*B**B*)

- Recontruct *K**→*K*S.
- Clean, no kinematically similar background
- Lower B.F. and lower efficiency : Fewer events than D0K analysis

*R**CP+ *=   1.73±0.36(stat.) ±0.11(syst.)

*R**CP**** *=   0.64±0.25(stat.) ±0.07(syst.)

*A**CP+ *= 0.08±0.20(stat.) ±0.06(syst.)

*A**CP**** *= 0.35±0.38(stat.) ±0.10(syst.)

- (*r**B*)*2* = 0.19±0.23

*R**CP+ *=   1.09±0.26(stat.) ±0.09(syst.)

*A**CP+ *= 0.02±0.24(stat.) ±0.05(syst.)

- Similar analysis, 121 MBB

##  from B→DK

**Combining results from GLW, ADS and D0-Dalitz methods**
**UTFit collaboration**
** ****hep-ph/0501199**

**   =  60°±28°    (+n)

##  from Belle

-  from Belle