UCSD Participation in BaBar

Vivek Sharma

University of California, San Diego

DOE Site Review 2005

2

BREAKING NEWS !

Luminosity !

The CP Detector

at PEP-II ring

3

BaBar Collects 1034 Luminosity From PEP-II !!

1

24hrs

-1Achieved Ldt 300 fb milestone : Oct '0

PEP II regularly delivers > 3 Design Lumi

Best Ldt 735 pb

! !

BaBar Efficiency > 96% Throughout

: Oct 6 -7 200

5

5

Touched 1034 instant. lumi again at 22:30, 9th Oct

4

Cumulative Luminosity

RUN 5

RUN 4

RUN 1

RUN 2

RUN 3

5

Detector Prepared for Higher Peak luminosity

DIRC PID)144 quartz

bars11000 PMs

1.5T solenoid

EMC6580 CsI(Tl) crystals

Drift Chamber40 layers

Instrumented Flux Return

Iron / Resistive Plate Chambers or Limited

Streamer Tubes (muon / neutral hadrons)

Silicon Vertex Tracker

5 layers, double sided strips

e

(3.1GeV)

e (9GeV)

Background conditions reliably extrapolated based on beam

currents & luminosity

All other systems fully capable of highest

luminosities

6Bottom & top sextants installed summer 2004

Remaining sextants in summer 2006

IFR Replacement of RPC with LST: Crucial Upgrade For ID

Now

: Barre

l RP

Cs

Now

: Barre

l LS

Ts

7

BaBar’s Physics Productivity

Journal Papers BABAR Belle

< 2003 32 54

2003 39 28

2004 52 35

June 2005 53 32

Total 176 149

Conference Contributions BABAR Belle

Papers submitted to ICHEP04 72 63

Abstracts submitted to LP05 75 73

8

Summary of UCSD Roles on BABAR

• Commissioning Detector– Survey PEP-II machine conditions prior to BaBar installation– pull together all elements of the SVT hardware, electronics &

data-acquisition software required to operate an SVT module during PEP II commissioning

• Drift Chamber operations– Hardware & software systems available early 1998 for

commissioning– Core online software, trigger, other system development– Participation essential for continuation of existing long-term

leading role on the project• Tracking & core software development

– Key element to early & successful physics CP violation program

– Built on considerable experience in tracking software for PIs and direct participation in DCH project

– core software contributions & calibration efforts for DCH• Collaboration management

– Near-term operations and long-term planning and development

• CP violation and B physics program !

9

• Gerhard Raven (May 1998-May 2002)

– Led DCH effort on calibration infrastructure, t-to-d extraction, tracking software & core offline software tools

– Tracking Coordinator for BABAR offline reconstruction (May 1999-May 2000)

– Co-convener of hadronic mixing AWG (Sep 2000-Jun 2003)

– Now at NIKHEF

• Riccardo Faccini (Apr 1998-Mar 2002)

– Worked on DCH calibration algorithms & DCH data analysis

– Leading contributor to vertex and composition tools design & implementation, micro-DST databases structure

– Convener for Charmonium AWG (Fall 1999-present) and Coordinator for sin2 analysis effort (Apr 2000-2002)

– Now Assist. Professor at Rome, current BaBar Analysis coordinator

The UCSD Team on BABAR

Past Postdocs

10

• Sören Prell (Oct 1999-Aug 2002)– Developed & maintained main fitting tools of sin2 and B0 mixing measurements,

including all related studies of reliability and sensitivity to systematic error sources– Leading effort on DCH t-to-d calibration studies and improvements, including

resolution (Aug 2000-present); DCH Operations Manager (Jul-Dec 2001)– Now Assist. Professor at Iowa State

• Shahram Rahatlou (Oct 2002-Jan 2005)– Reconstruction Manager for BaBar offline software– Software czar for Breco analysis working group common software – Measurement of BD(*)0 K(*)0 modes sensitive to sin2– Now Assist. Professor at Univ. of Rome

• Daniele del Re (Jan 2003-present)– Leader/liaison for software migration of Breco AWG to the CM2 (2003-04) – Co-convener Breco AWG (July 2004-Present), Recoil side Physics WG Coord.– Leading role in Vub measurements with Breco sample and CM2 implementation

– Transitioning to CMS to fulfill urgent UCSD need• Search in progress for Rahatlou replacement; identified strong candidate

The UCSD Team on BABAR

Present Postdoc

11

• Shahram Rahatlou (Sep 1998-Oct 2002)– Worked on micro-DST database, composition tools, Monte Carlo support for

analysis, and first B meson reconstruction– Wrote, supported and documented BRecoUser analysis package, including

production of skimmed ntuples, main support role for sin2 and mixing, essential for determinations of mistag rates

– Online DAQ operations manager from Aug 2000-Feb 2001– Main Ph.D. student on sin2 measurement

• Haleh Hadavand (Sep 1999-present)– 5th-year Ph.D. student, full-time research at SLAC – Involved in DCH calibration work and DAQ online manager– Produced B+/B0 production ratio measurement; instrumental in refining KS

efficiency understanding– Time-dependent CP violation in Penguin mode– expect to finish by end 2005

The UCSD Team on BABAR

Graduate Students

b s 0 0 0 0S S SB K K K

12

The UCSD Team on BABAR

• Edward Hill (Sep 1999-present)– 5th-year Ph.D. student, full-time research at SLAC – Involved in DCH calibration work and DAQ online manager– Thesis on precise measurements of Vub using fully reconstructed Breco

Sample ; expect finish in next six months

• David MacFarlane: DCH System Manager (1995-2000); Publications Board Chair (Nov 1999-Nov 2001); Executive Board member (Jun 2001-Oct 2003); Chair, Long-Term Upgrade Task Force (Feb 2002-Jan 2003); Spokesperson (Sep 2004-present). Plans to move on to SLAC

• Vivek Sharma: SVT liaison for ComDet, Speakers Bureau Chair (Jun 2000-Jun 2001); Founder & Co-convener of Breco AWG (Sep 1999-Sep 2004), Publications Board (Oct 2002-Sep 2005)

Other Major Roles

Recent BaBar Results where UCSD Physicists Have Played Important Roles

Focus on measurements defining Or Testing The Unitarity Triangle

* * *Unitarity: 0ub cb tbud cd tdV V V V V V

14

0 0 + -( ) , B B

0 0/ B D D K 0 0 0( ) SB B cc K

0 0 0( ) SB B ss K

measure UT angles by measuring CP violating asymmetry in B decayuB X

0

0 0

oscillation rate

B

B

*bud uV V

*ttb dV V

* bcd cV V

cB X

Over-Constraining The Unitarity Triangle

measure UT sides by measuring B semileptonic and radiative decay rates

Measure both !Angles and Sides

15

0B

fiCPA e

CPf

0B2iq

ep

fi

CPA e

CP Violation in B0 System

Directly related to CKM angles for single decay

amplitude

0 I mCPf

For single amplitude

0 0

0 0

( ) ( ): ( )

( ) ( )

sin cos

CP AsymmCP

CP CP

CP CPf

CP CP

f d f d

B t f B t fA t

B t f B t f

S m t C m t

2

2

1 | |

1 | |CP

CP

CP

ff

f

C

2

2Im

1 | |CP

CP

CP

ff

f

S CP

CP

CP

ff

f

Aqλ

p A

CPV through interference between mixing and decay

amplitudes

16

Cartoon of (4S)B0 B0 Evolution & Decay

17

sin2From bccsis Now a Precision Measurement

sin2 from these final states belongs to a special class of definitivemeasurements in particle physics• Theoretical uncertainties << 1%, so its interpretation is clear • data-driven measurement, statistics limited, with very little

dependence on simulation or theoretical assumptions.

0B 0 0 0,S LK K K

1 / , (2 ), , c cJ S

*0 0 0SK K

UCSD group played leading role in defining sin2 and similar time-dependent CPVmeasurement in BaBar, analyses(based on our method) now gets updated routinely following each major growth in data sample

SKIm( ) sin 2

18

Prize For Best PhD Dissertation At a US University or Laboratory

Citation:

"For his role in the development of the tools needed for the analysis of B factory data, including the tFIT program, a unique and comprehensive fitting framework for time-dependent analyses. The

tools he developed played a key role in the observation of CP violation in the B system by the BaBar collaboration. These tools will be essential to the ongoing program of work as the B

factories continue to probe the origins of CP violation."

PhD Thesis Advisor : Vivek Sharma

2004Mitsuyoshi Tanaka Dissertation Award

to Shahram Rahatlou

University of California, San Diego

19

sin2from B cc K0

BJ/ψ KL (CP even) modeB(cc) KS (CP odd) modes

asymmetry is opposite!

sin2 = 0.722 0.040 (stat) 0.023 (sys) PRL 94, 161803 (2005),(hep-ex/0408127)

0B 0 0 0,S LK K K

1 / , (2 ), , c cJ S

*0 0 0SK K

227 M BB

20

Evolution of sin2 measurements

Present CKM

fit

Present WA

BABAR 0.722±0.040±0.023Belle 0.652±0.039±0.020

First precise test of the CKM picture, has led to a paradigm shiftLook now for corrections rather than alternatives to CKM ansatz

Probing The CKM Angle : “Dodging Penguins”

UCSD Role: VS & DBM (with Jawahery, Hocker) = Review CommUncommon analysis (VS) Complete immersion in analysis for over 2 years

22

CKM Angle and Penguin “Pollution”• Original hope was to measure from TD CPV in B0 + -

* *

* *sin(2 2 2 ) sin 2

tb td ud ub

tb td ud ub

V V V VB

V V V V Im

Neglecting Penguin diagram

*

2

and depending on its re

Weak Phase in Penguin term

l. strength w.r.t Tree. (Pe

is arg( ) different from Tree, so it will modify

nguins are large in B !)

S = 1-C sin

td tbV V

Im

eff eff2 ; ; ?? Penguin Penguin

2ie 2 ie

T P

23

Recent Breakthrough: CKM Angle From CPV in B0 + -

0.080 33 0.24 0.140 03 0.18 0 09

long

long

S .

C . .

0 (232 pairs) B M BB 0 (232 pairs) B M BB

Signal: 617 52 events0.0210.978 0.014 0.029longf

BBAABBARARBBAABBARAR

00 00

peng0

0eff

0 5

in B system

Penguin pollution smaller than in B ;

| A | | A | , small small| A

much

11 9

| | A |

Br(B ) 30 10 ,( x6 larger than

Measurements show (who knew!) that

0%C

)

easu

L

m

CP=+1 red to be almost pure

(Longitudinally polarized)

24

Constraints On Dominated By B0 + -

Mirror solutions

disfavored

o

From combined , , results:

10103 9

o indirect constraint

13fi t: 98 19

CKM

BABAR onlyBABAR onlyBABAR onlyBABAR only

People can do unimaginable things with good quality data

samples!RC: VS, DBM, Jawahery, Hocker

Probing The CKM Angle :Clean Modes Are Rare

UCSD Role: B-DK- analyses developed in Breco AWG under guidance of conveners VS (2003-4) and del Re (2005)B D0K0 analysis authored by Rahatlou & VS

26

CP Asymmetry In BDK Decay

0K

Look for B decays with 2 amplitudes with relative weak phase

iV eub

Relative strength of the two B decay amplitudes matters for interference

Want rb to be large to get more interference Large CP asymmetry

0.1-0.3

27

from B±D0 K±: D0 KS + - Dalitz Analysis

2 2 2 ( ) 2 2 2 For : | | | ( , ) ( , )| i

bB A f m m r e f m m

2 2 2 ( ) 2 2 2 For : | | | ( , ) ( , )| ibB A f m m r e f m m

2 0 2 2 0 2 Defining ( ) ; ( ) S Sm M K m M K

2

( )ibr e

2

sKm

2

sKm

2

SKm

2

sKm

0 D 0 D

2A

Schematic view of the interference

0S

+ -B

Simultaneous fit to D K Dalitz distribution of

B info on and B r , data giv and ste rong phase s

28

B D0K D0 KS +- Dalitz Plot Distributions

B+D0K+ BD0K

B+D0K+ BD0K

Differences between B+ and B plots signify direct CP violation.

Analyses STATISTICS limited

29

: BABAR and Belle results (Dalitz method)Observable BABAR (+stat+sys+model) Belle (+stat+sys+model)

rB (D0K)

rB (D*0K)

rB (D0K*)

direct CP

significance

0.21 0.08 0.03 0.04

0.160.110.12 0.02 0.04

0.25 0.18 0.09 0.04 0.08

(68 15 13 11) (67 28 13 11)

non-K*

0.12 0.08 0.03 0.04

0.17 0.10 0.03 0.03

0.50 (0.75) @ 1 (2 )

rB value controls the CPVnot well measured so far

Br

( ) (degrees)

0.1 0.2

The error on is very sensitiveto the value of rB

2.32.4

30

Prospects For sin(2+) with B0/B0 D(*)0K(*)0

• Interference between decay and mixing • Advantages:

• Expected large asymmetries

• Time-dependent measurement with K KS

• Probe rB in self-tagging final state KK

– Disadvantages:• Color suppressed decays: Smaller (x 50) branching fractions than Ks• Analysis is data starved !

* A i i iub cs BrV V e e e * Acb usV V

0 0 (*)0 *

*0 0 (*)0~ 0.4ub cs

Bcb us

A B D K V Vr

V VA B D K

Strong phasedifference

b c

d d

u

s

0(*)D

0(*)K

*cbV

usV0B

b

c

d

u

s

ubV

*csV0B

b

0B

d

d

0(*)K

0(*)D

31

B DK0 Yields and Rates

Mode BF (10-5)

DK 5.3 ±0.7 ±0.3(syst)

B DK 3.6 ±1.2 ±0.3(syst)

205 million BB Preliminary

N104 ± 14 N17 ± 5D0 Sidebands

Com

b./0

.01

GeV

Com

b./0

.01

GeV

D0 Sidebands

E(GeV)E(GeV)

BaBar

Signal yields are as expected

*

Shahram RahatlouVivek Sharma

32

Probing rB From Self-Tagging B0 D0K*0 & B0 D0K*0

Mode B.F. (in 10-5)

B DK 4.0 ±0.7 ±0.3(syst)

B DK -0.50.50.3(syst)

<0.24 @ 90% CL

205 million BB Preliminary

N=77 ± 13

Vcb transition Vub transition

0 0 *0 0

*0;

B D K D X

KKK

0 0 *0 0

*0;

B D K D XK K

K

BaBar

Analysis statistics limit

B

ed

r 0.42@90%CL

E (GeV)E (GeV)

33

Unitarity Triangle from CP Violation Measurements Alone

New B Factory milestone:

Comparable UT precision from CPV in B decays alone

Overconstrained: subsets of

measurements can be used to test for

new physics

12 o o

o

9

o

(99 ) , = (22 1.3) ,

= (66 17

(187 21

)

)

Probing New Physics Contribution to CP Violation Via “Penguin” Loops in B Decays

New Physics ?

Standard Model

<< Testing Vs “” >>

SM

UCSD contribution: CPV in clean B0KS KS KS ; H.Hadavand Thesis

35

Compare sin2 with “sin2” from CPV in Penguin decays of B0

Both decays dominated by single weak phaseBoth decays dominated by single weak phase

b s

, ,u c t, ,g Z

tb tsV V

Penguin:

s

dd

s

Tree:

b

dd

W cbV

csV

0K

c /J

s0K

New Physics? 3

0 0 0, , ,

2

/ / /S L S L S L

icb csJ K J K J K

cb csB K

V Vq qe

p V V p

c

0 0 0, , ,

2~S L S L S L

itb tsK K K

tb tsB K

V Vq qe

p V V p

b ccs

b sss

?[charmonium]sin2 [ -penguin]sin2 s

0

-i2

In SM, interference between B mixing and dominant b sss (b suu)

[penguin amplitudes have no CKM phase]

Loop di

gives t

agrams s

he same CPV (due

ensitive to high

to e )

vi

as in b c

rtual mass scale

cs

s

NP coupling can bring in new phases that may cause deviation

sensitive to ne

s from expected

w physi

"si

cs

n2 "

Must be if one amplitude dominates

36

B0

KK00ss

KK00ss

KK00ss

0

0

10.59.8

0.380.323

0.280.253

86.7

0.71 0.04

0.34 0.05

s

s

sig

K

K

N

S

C

0

0

10.59.8

0.380.323

0.280.253

86.7

0.71 0.04

0.34 0.05

s

s

sig

K

K

N

S

C

Haleh Hadavand Thesis

37

Summary of “Penguin” Vs : Summer 2005

: 237 million pairsBelle: 386 million pairs

BABAR BBBB

2.4 between CP violation in s-

penguin vs sin2 (cc)

About 0.5 loss vs Winter 2005 due to shift

in charmonium average

(new Belle value lower than previously)

Charmonium

s-Penguins

38

How Good is The SM prediction For Penguin Modes?

2-body:Beneke, PLB 620 (2005) 143

sin2 penguinS

3-body:Cheng, Chua & Soni,

hep-ph/0506268

Calculations within framework

of QCD factorization

greblu

y =e = 1

full s

ig ae

mrang

Theory suggest > 0,opposite to exptal observation

Tantalizing at presentNeed more data to clarify !

Haleh’s modevery clean !

39

Recoil Side Physics : A UCSD Innovation• Crucial measurements of sides of UT require digging out tiny

signal from normally overwhelming background. Examples are

– bu l for Vub measurement

– bs and bd for |Vtd/Vts| measurement

• Spinoff from sin2 project Algorithm for reconstructing massive samples ( 4000/fb-1) of fully reconstructed B mesons

• Use knowledge of kinematics of fully reconstructed B to study decay of recoiling B in (4S) B B

BRecoBBrecoreco

BBrecoilrecoil

XXuull

ee--

DD**

ee++

Dan

iele

del

Re

Measurement of |Vub| from Inclusive Semileptonic Decays

*V V

cd cb

Vud

*Vub

BaBar data used in Aneesh’s |Vcb| analysis derived using the recoil side physics method

41

Inclusive Semileptonic Decays: The Big Picture

*D

,...,

,,22G

cb mm

|| cbV

|| ubV

Shape

Rate

Inclusive El spectrum

2|| cbV

2|| ubV

2|| cbV

El[GeV]

Shape

Rate for Mx<1.55

Inclusive Mx spectrum

(log-scale)

B

X

|Vxb|2

bul

42

Brecoil

BrecoD* Y(4S) l

Xu

Reco side Recoil side

•MX reconstruction•Kinematic constraints to improve MX resolution

Y(4s)

Xu

l

BY(4s)

D*

B missing mass

squared

B Candidate Mass

Recoil Side Measurement of bul Kinematics

Can now “Reconstruct” Neutrino 3-vector, q2

Good Example of Recoil-side physics

43

Isolating bu l From Dominant (x50) bc l background

3(4.76 0.34 0.32) 10 ubV

signal region

mX (GeV)

q2 (

GeV2

)

2 3exp( 1.7 , 8 ) (0.87 0.13 0.01 )10

b u x theoBR M GeV q GeV

Analysis sensitivity (Stat. vs Theory error) optimized for present sampleGood to reach ~ 6% theory precision with x 3-4 data samples

theory

bu

bc

bumisreco

44

Bottomline on Vub From Inclusive Measurements

The Recoil side methodhas the best potential for precise measurementof |Vub| with larger data samples + bs data

BaBar measurements led by Daniele del Re & Ed Hill (thesis)

Hill's thesis incorporates

0

4.94 0.41 0.26

b s da

1

ta

.3

ub stat sys eot thV

45

The Emerging Big Picture

Overconstrained: growing set of independent

measurements are remarkably

consistent with CKM picture

With improved Measurements of |Vub|

46

0

200

400

600

800

1000

1200

Ju

l-9

9

Ju

l-0

0

Ju

l-0

1

Ju

l-0

2

Ju

l-0

3

Ju

l-0

4

Ju

l-0

5

Ju

l-0

6

Ju

l-0

7

Ju

l-0

8

BaBar Projection For Data Sample Growth

Double from 2004 to 2006

ICHEP06

Double again from 2006 to

2008 ICHEP08

Inte

gra

ted

Lu

min

osit

y [

fb-1]

ICHEP04

47

Future Activities of UCSD-BaBar Group

• Since BaBar’s beginning, UCSD PIs, post-docs and students have led BaBar’s productivity

• MacFarlane’s stated move to SLAC in Jan 2006 diminishes UCSD’s current high profile role in BaBar management and participation in BaBar beyond 2008

• Does not significantly alter UCSD’s ability on near term (2008) physics objectives which are based on our long term investments in :

– Precise measurement of Vub from fully reconstructed B sample using recoil side technique pioneered by UCSD

– Search for bu amplitude in B0 D0K0 family of decays in pursuit of angle – CPV in bs Penguin decays as clean barometer of NP

• Each of these measurements have a well defined & vetted analysis procedure in place (analysis method published already) but are each currently STATISTICS limited.

• In 2006, plan to shrink the UCSD-BaBar group to

– 50% of VS (other 50% directed to CMS) ;

– One full time post-doc concentrating on physics analyses above

– retain possibility of one graduate student doing BaBar analysis and then moving to CMS DAQ in ~2008

• Yet deliver on the physics goals stated above assuming projected luminosity profile

48

Thanks for generously supporting the CKM2005 workshop at UCSD • Essentially six workshops within a workshop + satellite meetings • Meeting attracted best of the best (~ 230 in all)• Lively discussions of new Expt. and theory ideas for future precision• Important service to the global Heavy Flavor Physics community

Local OrganizersBen Grinstein, Aneesh Manohar, Frank Wuerthwein, VS

Unused Slides

50

Ranking Penguin Modes by SM “pollution”B

ron

zeS

emiG

old

Go

ld

b

dg

t0B

d

ss

s

W 2~tb tsV V

0K

0', f

0K

b

dg

t

d

ss

s

W

0B

2~tb tsV V

b

dg

t0B

d

ds

d

W

2~tb tsV V 0 0, ,

0K

2( )

~ 5%

~ 5 10%

2( / )

~ 20%

2( (1 / ))qqf

b

dg

u0B

d

ss

W 4~ i

ub us uV V R e

4~ iub us uV V R e

W b

d

0B

d

uu

0', f

s 0K

0Ks

4~ iub us uV V R e

W b

d

0B

d

uu 0 0, ,

s 0K

Decay amplitude of interest SM PollutionNaive (dimensional) uncertainties on sin2

Note that within QCD Factorization these uncertainties turn out to be much smaller !

51

Outline of This Talk

• Brief status of PEP-II and BaBar

• UCSD Participation in BaBar

• Recent BaBar physics results highlighting UCSD contribution

– Probing the Unitarity Triangle with BaBar• angles and • CKM element Vub

– Anticipated BaBar data samples (2008)

– UCSD physics goals with Incoming BaBar Data• UCSD Physics goals clearly formulated

• Analysis methods well established, statistics limited

• Straightforward analysis of ever-increasing BaBar data samples

• Thank you for generously supporting the CKM2005 workshop at UCSD

– Meeting attracted the best of the best (~ 220 in all)

– Lively discussions of new exptal and theory ideas for high precision

– Rated unqualified success by the Heavy Flavor Physics community

52

Drift Chamber Electronics Upgrade

• Motivation: – Remove anticipated deadtime problem due

to serialization and shipping of data from DCH to readout module

• Upgrade in two steps:– Phase 1 (summer 2004)

• Ship only 1/2 ADC waveform information (3216 bytes) from front ends

• No impact on dE/dx performance

– Phase 2 (Oct 2005) • Larger FPGA to allow feature extraction

before transmission• New boards produced, tested & ready for

installation

53

Reminder Of The Terminology

VtdVtb*

VudVub*

VcdVcb*

*cd cb

*td tb

V Varg

V V

*td tb

*ubud

V Varg

V V

*ubud*

cd cb

Varg

V

V

V

In a time-dependent CPV measurements:

With only one amplitude driving the decay,

Direct CP asymmetry C=0

CP CP CPf f d f d

f fA ( t) S sin m t C cos m t

f f

54

BaBar Physics Highlights: Discovery of Direct CPV in B Decays

2 iSM amplitude e T P sinKA

( )A B f

2 2Bf f

B( )A B f

2 2

2 20 Direct

ff

CP

ff

A ABr B f Br B fA CPV

Br B f Br B f A A

B0K+

B0K+

CPV4.2

BABAR

signal enhanced

0.133 0.030 0.009 CPA

First Observation (4.2

Confirms at ICHEP04

0.101 0.025 0.005 CPASignal (in 274M BB pairs): 2140 53

Average 0.114 0.020 CPA

3.9BelleBelleBelleBelle

BBAABBARARBBAABBARAR

M BB Signal (in 227 pairs): 1606 51

55

Physics Analysis Focus of The UCSD-BaBar Group

UCSD-Babar group led the measurements of sin2 from B charmonium modes between 1998-2003. These measurement has now become “routine”. UCSD group has moved on more challenging measurements.

With the large data set BaBar is accumulating our major physics focus is now on:– Search for the decay B0 D0 K0 and measurement of CKM

angle by time-dependent CP asymmetry. – Developing massive samples of fully reconstructed B mesons

for Recoil side B meson decay studies. The aim is to measure CKM element Vub from inclusive and exclusive bu l decays

– Probe CP violation in Penguin decays such as

– Measurement of production ratio

b sss0

S S SB K K K0 0(4 )

(4 )

S B B

S B B

Brief Description of UCSD analysis follows

56

UCSD Physics Activities On Babar

• David MacFarlane (PI):

– Main author of BaBar 2002 Phys. Rev. (D) on Measurement of B oscillation and CP violation.

– Measurement of inclusive bu l spectrum (with Student Ed Hill)

– Search for Time-dependent CP asymmetry in B0 KS KS KS (with student Haleh Hadavand)

– Measurement of production ratio (with student Haleh Hadavand)

– BaBar Spokesperson

0 0(4 )

(4 )

S B B

S B B

57

UCSD Physics Activities On Babar

• Vivek Sharma (PI) : – led, as co-convener, the BaBar physics group on Exclusive B decays to Open

charm ( BRECO group) between 1999 –July 2004. All analyses involving exclusive hadronic B Charm reconstruction are developed in this group. Guided thru publication 9 PRL, 2 PR(D)RC and 2 PR(D) articles and multiple conference papers including 11 papers at ICHEP04 in Beijing.

• Physics goals of the BRECO group include:– exploration of decay modes capable of measuring CKM angle and sin2+– Decay dynamics in hadronic B decays to charm– Spectroscopy of new charm mesons from their production in B decays– Develop large sample of fully reconstructed B mesons for measuring

inclusive properties of the recoiling B meson. This paradigm shifting enterprise is already contributing to several key measurements in B decays such as Vub and measurement of photon spectrum in b s decays .

• Breco group oversees the physics analysis of about 80 BaBar physicists from US, France, Italy and Germany. It is one of the largest analysis groups in Babar.

– Guiding role in BaBar observation of CP violation (sin2) in BJ/K0 . Main author of the 2001 and 2002 PRLs on measurement of Sin2

– Member (since 2002) of the Babar Publication Board.

58

UCSD Physics Activities On Babar

• Shahram Rahatlou (Post-doc):

– Major contributions to BaBar observation of CP violation in B decays to charmonium (e.g. BJ/K0). Tools and samples he developed (BrecoUser, tFIT etc) are still used in many CP violation studies. Awarded The 2004 APS Tanaka prize for the best PhD thesis at a US university or Laboratory.

– BaBar Event Reconstruction Manager since Jan 1, 2004. • The reco manager is Responsible for development and deployment of the common aspects

of reconstruction, including the reconstruction geometry & alignment calibration model & code, the overall organization of reconstruction executables, and the reco infrastructure packages. He is responsible for the system-specific aspects of the reconstruction code to the level desired by the specific system managers. The reco manager is responsible for the technical aspects of the reco software within the five systems and their integration into the whole.

• Shahram brings a unique and comprehensive knowledge of Babar analysis tools, computing and physics to this job. His leadership has been crucial in ensuring prompt and high quality event reconstruction and allowed BaBar to analyze the data collected till the end of Run 4 in mid July and present results based on it at the Beijing ICHEP04 in mid-August !

– Developing the time-dependent CP asymmetry analysis of B0 D0 K0 for measurement of sin2+ and . First results presented at ICHEP04 (hep-ex/0408052 ).

59

UCSD Physics Activities On Babar

• Daniele delRe (Post-doc):

– Primary physicist in the development of large sample of fully reconstructed hadronic B decay (Semi-exclusive B sample).

– Co-convener of the “Recoil Side Physics” forum in BaBar in charge of coordinating and assisting in the development of a variety of inclusive measurements in the decay of the B meson recoiling against the fully reconstructed B meson (in the semi-exclusive sample).

– Led the pioneering measurement of Vub by measuring the hadronic mass spectrum in b u l from the recoil side B. Results published in PRL (92) 07180, 2004. Updated Vub results with more data (x 3) and improved observables in preparation.

– Key contributor in the migration of BaBar analysis software to the new computing model implemented since September 2003. Technical coordinator of the data and MC “skims” and tagbits for the Breco and Semileptonic Physics groups.

– Appointed co-convener of the Breco Physics group in August 2004.

60

UCSD Physics Activities On Babar

• Haleh Hadavand (PhD. Student):

– Member of BaBar charge Particle tracking group with important contributions to the Drift chamber calibration and Ks reconstruction studies. Her tracking efficiency studies provide the official BaBar “recipes” for all analyses involving branching fraction measurements.

– Primary author of the measurement of the B+/B0 production ratio from the (4s) Meson using B+J/ K+ and B0J/ Ks decays  to be published in Phys. Rev. (D).

– Primary author of the measurement of time-dependent CP asymmetry in penguin dominated mode B0 KS KS KS .

• Edward Hill (Ph.D Student):

– Drift chamber calibration.

– Migration of BaBar analysis software related to Semi-leptonic decay physics to the new computing model and data-mining for the entire semi-leptonic physics group.

– Developed algorithms for bcl background rejection for Semileptonic physics group

– Measurement of Vub from inclusive semi-leptonic decay using the photon energy spectrum from b s decays.

61

Self-Tagging B0 D0K*0 and limit on rB

Mode BF (10-5)

BDK 6.2 ±1.4 ±0.6

BDK < 4.1 @ 90% CL

124 million BB

No Signal inVub mediatedDecay

N=45 ± 9

Charge correlation toseparate B from B

Vcb transition

Vub transition

0 0 *0

0

*0

KK

B D KD X

K

0 0 *0

0

*0 K

BXK

D KD

K

Preliminary

Results based on more data and refined analysis technique forthcoming; targeted forpublication in early 2005.

62

New Idea: Measurement of |Vub| From Semileptonic B Decays recoiling against (large samples of) Fully Recostructed B mesons

Capitalizes on UCSD Expertise in B meson Reconstruction (Breco Samples SemiExcl Samples)

Measurement of | Vub | From Inclusive and Exclusive Final States

63

• Hermiticity, so vital for SL measurements is not the best feature of Belle/ Babar detectors due to intrusion of machine into detector

• But B-factory detectors recording ever increasing samples of BB pairs (> 250 Million BB recorded already 1000 Million soon)– At the price of modest efficiency (4%), can fully reconstruct one B decay into all

hadronic final states (Breco) and examine the other (recoiling) B decay • This “Recoil side” studies perfectly suited for many Vxb studies • Much “cleaner” and more powerful than neutrino reconstruction a la CLEO • This is the most promising way for the future Vub and other Semileptonic

measurements

Beginning of an Experimental Paradigm Shift in Vxb Measurements in Semileptonic Decays at B Factories

64

The Perfect (4S) Event: Example of Recoil Side Analysis

In this (rare) case all particles were

sprayed within fiducial volume of detector

Replace this with your Favourite Vxb modee.g: b u l

65

Require Lepton (p*>1.0GeV)

S/B~0.3

S/B~2.5

Hadronic B Decay Reconstruction Rate: 4000/ fb-1

World’s largest sample of Fully reconstructed B mesons 1,000,000 and growing!

80fb-1

Full B reconstruction on one sideprovides kinematic constraints andBackground reduction allowing Important inclusive B decay Measurements like Vub.

Largely the work of UCSD postdoc Daniele delRe

66

Exclusive Final States: B () l

Approach similar to the inclusive analysis but

resonances are exclusively and fully reconstructed on recoil side.

We measure, very cleanly and over large kinematic range:

In Breco SampleIn Breco Sample

As Lattice calculations become more robust, measurement of B l rate over large kinematic range may lead to one of the best measure Vub precisely.

Experimental measurement is statistics limited

0 4( ) (2.57 0.52 0.59 ) 10stat systB B l

0 4( ) (1.08 0.28 0.16 ) 10stat systB B l

B±l

B±l

B0l

B0l

0B l

67

0 0

(4 )1.006 0.036( ) 0.031( )

(4 )

S B Bstat sys

S B B

0 0

From clean samples of

/

/

SB J e e K

B J e e K

Measure ratio of branching fractions:

0 0 0

/

/ S

B J Kand

B J K

Determine production ratio

assuming isospin:

0 0 - (4 ) and Rates : Needed for all Br. Ratio MeasurementsS B B B B

Haleh HadavandDavid MacFarlane

Accepted in PR(D) RC

68

CPV In Pure s-Penguin Decay B0KS KS KS

• New probe of CPV in s-penguin decays, clean signal

• Perform Ks and B vertexing using 5 layer Silicon tracker (technique pioneered by BaBar and tested on BKs0

sample). Often one of three Ks decays inside SVT.

• Reconstructed B vertex resolution sufficient for time-dependent CPV measurement a la B J/ KS

• First analysis of its kind, currently “blind”, expect public results and publication by early 2005.

• CPV precision expected to be statistics limited, will improve with rapidly accumulating BaBar data

yx

-

~4 m

Inflated Beam

Beam~200 m

0B

+

K0s

~30 m

+-

K0s

+

-

K0s

KS

KS

KS

90 10 signalafter bkgnd subtraction

Hadavand

69

UCSD-Babar Physics Outlook

• Golden years of Babar physics productivity enabled by excellent PEP-II running and success of the new Babar computing model

• UCSD-Babar physicists continue to play a key role in BaBar productivity by contributing to physics and computing leadership, service tasks and by performing outstanding and topical analyses.

• The UCSD-Babar group’s planned near-term physics focus is on– Strategies for measurement of , particularly B0/B0 D(*)0K(*)0

– Determination of |Vub| with the novel recoil side method

• Inclusive bul measurements• Exclusive bul final states (exploring new ideas such as that of

Grinstein & Pirjol hep-ph/0404250 )

– Innovative new probe of CPV in s-penguin modes with B0 KSKSKS

70

CP Violating Asymmetry From Interference Between Mixing &Decay

2

2 2

12 Im( )

1 1S C

1 Im , 0S C 1 decay amplitude, |q/p|=1:

0* *212 12

0212 12

iCP f

ifCP

f H B AM q

M p Af H B

1 decay amp: magnitude & strong phase divide out!

phase inB mixing

71

+e-e

B0 J/ KsB0 J/ Ks

Time Dependent CP Violation in Picture

z

Δ zΔ tβγ c

Brec

Btag 4s

(4S) = 0.55

z-π

0sK

+π

+μ-μ

Coherent BB pair

B0

B0

Separate

B0 and B0

Separate

B0 and B0