# Presentation: 034879

##  and  measurements from BaBar

- LPNHE Paris – Université Paris 6
- For the BaBar Collaboration

****** ****and ******** measurements from BaBar**

**PANIC 2005**
**Santa Fe, New Mexico, USA**
**October 24****th****-28****th**** 2005**

## Introduction

**Introduction**

****** ****and ********: challenging measurements**

-  from , ()0:
- “penguin pollution”

-  from B+D(*)0K(*)+:
- small interferences

-  precisely measured with
- golden modes J/ KS, D*D*,...
- sin(2+) from B0D/

**CKM standard fit without **
****** ****and ******** measurements****:**

## Measuring with B: SU(2) symmetry

**Measuring******** with******** ****B************: SU(2) symmetry**

- “Penguin pollution”:

- Time dependent asymmetries in h+h-:

**Tree:**

**Penguin:**

- Neglecting P, S measures :

- In reality it measures eff  additional info. needed for 

- Isospin analysis:

- Neglecting EWP,
- h+ h0 (I=2)=pure tree

**Triangle relations allow determination **
**of penguin induced shift in ********: |******** - ********eff****|**

- Gronau-London, PRL, 65, 3381 (1990)
- Lipkin *et al.*, PRD 44, 1454 (1991)

## Results for B

** ****No observation of CP violation**
** ********0********0**** observation**** (indicates**** non-negligible contribution of penguin****) and ****measurement of C****00**
** ****New meas. BR(********+********-****)**** with efficiency corrected for the effects of final-state radiation**

**Results for B******

- C = -0.09  0.15  0.04
- S = -0.30  0.17  0.03

- HEP-EX 0508046 (2005)

- PRL, 95, 151803 (2005)

- PRL, 94, 181802 (2005)

**sPlot**

**Signal enriched sample**

**Signal enriched sample**

**sPlot: ********+********0****, K****+********0**** **

******+********-**

******0********0**

******+********0**

## Results for B

** ****interference with a****1********, ********, ******** neglected (********small syst.)**
** ****B bkg = main source of syst.**

**Results for B******

**Signal enriched sample**

**Signal enriched sample**

- PRL, 94,
- 131801 (2005)

- PRL 95, 041805, (2005)

******V-V state: need angular analysis: more difficult**

*transverse*

*longitudinal*

** ****No significant signal seen**
** ****f****L****=1 assumed for most conservative upper limit**
** ****small BR******** small penguin contribution in ******** modes**
**  ******** ****good sensitivity to ******** expected**

******Data: 227********10****6**** B pairs**

******Data: 232 ********10****6**** B pairs ******

******+********-**

******0********0**

## Measuring with B()0+-0 : Dalitz analysis 

**Measuring******** with******** ****B********(********)****0********+********-********0**** : Dalitz analysis **

- A. Snyder and H. Quinn,
- PRD, 48, 2139 (1993)

- Interference between the  resonances at equal masses-squared gives information on **strong phases **between resonances****** ******** can be constrained without ambiguity**

- Isospin analysis:

- Time dependent Dalitz analysis assuming Isospin symmetry:

*f**k** relativistic*
*Breit-Wigner*
*form factors*

- Not a CP eigenstates  pentagonal relations
- EWP neglected: 12 unknowns for 13 observables  in principle possible
- Unfruitful with the present statistics: current data does not constraint 

- Direct CP asymmetries:

## , ,  CKMfitter = (103+10-9)o  

-  8 solutions within [0,]
-  Need more statistics
- 
-  Golden mode for  (smaller penguin
- contribution in  modes wrt )
-  Additional assumption: neglect possible
- I=1 amplitudes (quasi2body assumption)
-  :
-  constrained with no ambiguity at 1
-  Combined constraint:
-  in very good agreement with CKM fit value

**Constraints on ******

**********, ********, ******** ****CKMfitter ****= (103****+10****-9****)****o**

****** ****= (113 ****+27****−17**** ± 6)****o**

##  from direct CP violation: B-D()K()-  

** ****from direct CP violation: B****-********D****(********)****K****(********)- ******** **

**b ********c color allowed**

**b ********u color suppressed**

**Relative strong **
**phase ********B**** unknown**

**Rel. weak phase ******

- Critical parameter: rB
- Larger rB, larger interference,
- better sensitivity to 

**G**ronau-**L**ondon-**W**yler: Phys. Lett. B265,172, B253 483 (1991)
- 	CP eigenstates

**A**twood-**D**unietz-**S**oni: Phys. Rev. Lett. 78, 3257 (1997)
- 	DCSD D0 and CA D0 ex. : B- → (K+ -)D K-

**G**iri-**G**rossman-**S**offer-**Z**upan: Phys. Rev. D68 054018 (2003)
- 	 D0 → Ks Phys. Rev. Lett. 78, 3257 (1997)

## Results for GLW (f=CP eigenstates)

**A ****CP+****R ****CP+****=-A****CP-****R****CP-**
** ****3 unknowns:**** ********, ********, r****B****(********)**** **

**Results for GLW *****(f=CP eigenstates)***

-  Theoretically very clean
-  No strong constraints yet on  because rB() small
-  Need more statistics

**hep-ex/0408082**

**PRD 71, **
**031102 (2005)**

**PRD 72, **
**71103 (2005) **

- 214106 B pairs

- 123106 B pairs

- 214106 B pairs

## Results for ADS (f=K+-)

**Results for ADS *****(f=K******+************-******)***

-  **Small branching fractions**
** ****Amplitudes ~ comparable**** **
** ****2 observables for 3 unknowns**

- D(*)K: rB<0.23 and  rB2 <0.162 @ 90%CL

- No signal seen

- Interference

** ****Input: **
**r****D****=0.06********0.002 **

- 232106
- B pairs

**hep-ex/0504047**
** **
**PRD 72, 71104 (2005)**

## Results for GGSZ: (f=KS+-)

**Results for GGSZ: *****(f=K******S************+************-******)***

**PRL 95, 121802 (2005)**
**hep-ex/0507101**

-  Final state accessible through many different decays  need Dalitz analysis
-  Weak phase ****, strong phase **** and magnitude of suppressed-to-favored amplitudes
- rB()  extracted from a fit to the interference pattern between D0 and D0 in the Dalitz plot

- CP fit
-  gives:

** ****12 x******** ****,**** ****y******** **** measured for three **
**modes: DK****-**** , ****D********K****-****,**** ****DK********-**** **
** ****can be converted into **
**constraints on ********, ********B****(********)****, ****r****B****(********)**** **

****** ****= (67 ± 28 ± 13 ± 11)°**** **

**1 and 2******** level contours**
** ****in the planes (******** , **
**suppressed-to-**
**favored ratio) from **
**the three modes DK****-**** , **
** ****D********K****- ****, DK********- ****taking all 3 **
**modes results **
**simultaneously**** **** **

- (GLW+ADS: rs=0.28+0.06-0.10)**  **

## Constraints on 

-  GLW and ADS methods:
-  limits on suppressed-to-favored ratios rB(*)
-   more statistics needed to really constraint 
-  combining different measurements helps: combination of GLW/ADS (WA)  and GGSZ(BaBar) with all measured modes:

**Constraints on ******

******GLW,ADS,GGSZ ****CKMfitter**** = (51****+23****-18****)****o**

******GGSZ ****= (67 ± 28 ± 13 ± 11)°**
**                 ****= (67 ± 33)°**** **

## Conclusions

**Conclusions**

-  All results in good agreement with the global CKM fit
-  Measure  at B-factories considered ~ impossible few years ago!
-  SM fit: ,  and  determine (,) nearly as precisely as all data combined
-  New era: constraints from angles surpass the rest with increasing statistics

-  Best  measurement:  (Lucky2: longitudinal polarization dominates and small penguin pollution)
-  Best  measurement: Dalitz analysis GGSZ

**********, ********, ******** ****WA****= (98.6****+12.6****-8.1****)****o**

******GLW,ADS,GGSZ ****WA**** = (63****+15****-12****)****o**

## Backup slides:

-  CKM matrix and unitarity triangle
-  PEP-II performances
-  The BaBar detector
-  Analysis techniques:
-  T measurement
-  B kinematical variables: mES and E
-  Event shape variables
-  Cherenkov angle
-  General common features
-  Further details on ,  isospin analysis
-  +- the golden mode for measuring 
-  Method for B()0 Dalitz analysis
-  Extrapolations for B isospin analysis
-  0 efficiency measurement
-  sPlots technique
-  Combined results for GLW and ADS in B-→D0K*-
-  GGSZ fit results

## CKM matrix and unitarity triangle

- 

- 

**CKM matrix and unitarity triangle**

- Quark sector: masses eigenstates  gauge eigenstates
-  Mixing between flavour and weak eigenstates described by
- 3 3 matrix with 3 real parameters and one single phase

- CP violation possible in the SM
- only if CKM matrix is complex i.e.
- UT area non zero i.e. 0

## The BaBar detector

- 1.5T magnet

- Electromagnetic
- Calorimeter (EMC)

- Detector of Internally
- Reflected Cherenkov Light (DIRC)

- Drift Chamber (DCH)

- Silicon Vertex Tracker (SVT)

- Instrumented Flux Return (IFR)

- Pairs of *B *mesons from (4S) decays: (4S)*B**0**B**0*, *B*+*B*-

- Boost of (4S) in the lab frame: bg  0.56

**The BaBar detector**

## PEP-II performances

**PEP-II performances**

## Analysis techniques: time dependent measurements

- 
- t=1.6 ps  z 200, 250 m

- Exclusive B meson reconstruction

**Analysis techniques: time dependent measurements**

**Time dependent measurements, flavor tagging:**
-  BB are in a coherent state at production
-  There is a coherent evolution until Btag decays
-  Breco’s flavour  determined from Btag’s flavour and t
-  Boost: t measured via space length measurement between Btag and Breco z
-  Flavor of the Btag is determined by its decay product: charge of leptons, kaons, pions

## Analysis techniques: kinematics and event shape

**Energy difference**

**Event shape**

******(m****ES****) ******** 3 MeV**

******(********E) : ****mode dependent**

- (4S) rest frame

**Analysis techniques: kinematics and event shape**

**Event shape variables examples:**

## Analysis techniques: K/ discrimination

**Analysis techniques: K/******** discrimination**

- Cherenkov angle versus momentum:

- K/ separation versus momentum:

- K/  >2.5 up to 4 GeV/c

## Analysis techniques: common features for , , 

**Analysis techniques: common features for ********, ********, ******

- The 3 analyses (B  ππ, B  ,  B  π (Dalitz πππ)) share **the same philosophy and use the same techniques**:
-  **Unbinned maximum likelihood** fit using mES, E, NN/F,  t, c for ππ/Kπ, Dalitz variables for π, resonance mass and helicity for .
-  Each component has **its own modeling** in the likelihood:
-  Correctly and misreconstructed signal events.
-  Continuum, charmed and charmless B backgrounds (up to 20 modes for ).
-  **Simultaneous fit** of Signal/background yields, free parameters describing the backgrounds, CP parameters and (polarization).
-  Determination of t resolution function and  mistag rates with **fully reconstructed events**.
** ****Better statistical sensitivity than traditional “cut and count” approaches. **
** ****Better control of the systematics thanks to this global likelihood technique.**

## Further details on,  isospin analysis

**Further details on********, ******** isospin analysis**

- _Assumptions:_
-   neglect EW penguins
-           (shifts  by ~ +2o) penguins
-   neglect SU(2) breaking
-   in *ρρ*: Q2B approx.
-                     (neglect interference)

- 13* *unknowns
- – 7 observ.
- – 5 constraints
- – 1 glob. phase  = 0  

- 2 isospin triangles and one common side

*B**+–**, S**** **, C***
*B**+*0, *A**CP*
*B*00, (*S*00), *C*00

***, *
*T**+*–, *P**+*–,
*T**+*0, *P**+*0,
*T*00, *P*00

- Account

- Constraints

- Observables

- Unknowns

-  can be resolved up to an 8-fold ambiguity within [0,]

## +- the golden mode for measuring 

******+********-**** the golden mode for measuring ******

**Analysis more difficult****:**
- 2 **π****0** in the final state.
- Wide **** resonances.
-  V-V decay:
- L=0,1,2 partial waves components:
** ****Need angular analysis**.
**But eventually the best mode:**
-  First measurement of α performed by *BABAR *in :  ***PRL, 93, 231801 (2004).***
-  Branching fraction ~ **6 times larger** than for B→ ππ.
-  Penguin pollution much smaller than in B→ππ
-  fL ~1.0   are ~100% longitudinally polarized, transverse part suppressed
-  at the tree level: (m/MB)2 ****** ****B****0********-********+**** is almost a pure CP-even state!**

- Helicity Frame

**Longitudinal**
**(CP-even state)**

**Transverse**
**(Mixed CP state)**

## Method for B()0 Dalitz analysis

**Method for B********(********)****0 ****Dalitz analysis**

- hep-ex/0408099

- 2 steps analysis:
-  Fit 16 Breit-Wigner parameters related to the quasi two body parameters *S*, *C*,...
-  Fit results + correlation matrix:

**213********10****6**** B pairs**

-  simultaneous extraction of weak and strong phases , 

## Extrapolations for B isospin analysis

**Extrapolations for B******** isospin analysis**

**Eur. Phys. J. C41, 1-131, **
**CKMfitter group, (2005)**

## Analysis techniques: 0 efficiency

**Analysis techniques: ********0 ****efficiency**

## sPlot technique

**sPlot technique**

- Reference: François Le Diberder and Muriel Pivk, physics/0402083

## Combined results for GLW and ADS B-→D0K*- 

**Combined results for GLW and ADS B****-****→D****0****K*****-**** **

-   [75o, 105o]
- @95.4% CL

- Frequentist approach (CKM-Fitter EPJ,C41,1 (2005)) to extract  and rb
- from ADS/GLW combination for B-→D0K*- modes:

** **

**Results for GGSZ: *****(f=K******S************+************-******)***

- NEW

**42 ****± 8**

**x******** ****,**** ****y******** ****:**** ****  **
** ****~ gaussian distributions**
** ****Small statistical **
**correlations**
** ****Frequentist treatment **
**to convert  them into **
**constraints on **
******, ********B****(********)****, ****r****B****(********)**** **