1#

BaBar: Study of CP violation in B decaysHassan Jawahery

Outline

UMD people in BaBar

A brief introduction to BaBar & its physics goals

An overview of Maryland contribution to the experiment

Future

More details on our program in following talk by D. Roberts, H. J.

2#

UMD in BaBar• Faculty:

– H.Jawahery & D. Roberts

• Research associates:– Wouter Hulsbergen (Since Sept. 2002-at SLAC)

• BaBar vertexing coordinator (Dec. 2002- present)• BaBar Tracking coordinator (Jan. 2003- Jan. 2005)• Co-convener of Radiative Penguin working group (March 05- present)• Physics analysis projects with Jawahery and students

– Chunhui Chen (Since Sept. 2003-at SLAC)• SVT operation manager• Physics analysis projects with Roberts and Students

– Gabriele Simi (Since Feb. 2005-at UMD)• SVT operations • Physics analysis with Jawahery and students

• Graduate students– Joe Tuggle (Started in summer 2004- at SLAC since summer 05) – Jake Anderson (Started summer 2005- at UMD)– Chung Khim Lae (To graduate in 2005-at SLAC)– Dmytro Kovalskyi (To graduate in 2005-at SLAC)

3#

BaBar’s Primary Physics GoalsCPV in B decays:

Is CP symmetry broken in B decays? Yes---- Done

Is the CKM the dominant source of CPV in the quark sector? Yes ---- Done

Is the CKM unitary?

More precise measurements of the angles and sides of the CKM unitarity triangle needed to settle this.

Search for physics beyond the SM:Search for the effects of N.P. (new particles, new sources of CPV,..) through virtual processes. Is the NP flavor blind? Or the masses of the NP particles are too large to affect this sector?

The main focus is on CPV studies of the “pure” penguin ( bs) decays .

Rare Tau and Charm Decays

Bread and Butter Physics of Charm, Tau and B Decays, Spectroscopy, ..

4#

3.1 GeV e+ on 9 GeV e- <> = 0.55

• Peak Luminosity ~3 1033 cm-2 s-1 reached >9x1033 cm-2 s-1 summer 2004 – down from July 04- March 05 due to upgrades and accident in Oct. 05.• Peak lumi back to 9x1033 cm-2 s-1- struggling to go up.

PEPII

Construction of the PEP-II asymmetric storage ring commenced in 1993

Construction of the BABAR detector began in 1994

PEP-II had first collisions in the Summer of 1998

BABAR was rolled onto the beamline in Spring 1999 and saw its first events on May 26, 1999

5#

PEP-II Interaction Region and the BaBar Detector

HER

LER

Collision point

BaBar

e e

6#

Data sample collected: 287.89 fb –1 (as of Aug. 14, 05)

1999 2000 2001 2002 2003 2004 2005

 1.62  23.76   40.05   31.32   56.71   77.19 37.24

7#

Lately--

8#

PEP-II Upgrade Plans after Run 5

• Lower y* down to 8mm

• Raise LER beam current from 3.3 to 4.5 A• Increase LER bunch current from 1.9 mA to 2.6 mA

• Raise HER beam current from 1.8 to 2.2 A• Increase HER bunch current from 1.05 mA to 1.3 mA

• Shorten bunch lengths to 9 mm

• Reach peak luminosity by Summer 2006

• Increase luminosity to 2.41034 cm-2 sec-1

9#

Goals for PEP-II 2004-2009

YearPeak Luminosity (x1033)

Total Integrated Luminosity (fb-1)

Fall 2003 6.78 150

Fall 2006 20 500

Fall 2008 30 1000

10#

A Brief intro to BaBar physics

11#

| |V Vc d c b

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The Unitarity Test

CPDefinitions

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12#

c.l. 90% @7441

11571

0.294.21

constraintfit CKM

oo

o

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o

degrees 63

degrees 6.98

degrees

:tsmeasuremenDirect

512

6.21.8

2.1

a

cos2 < 0 ruled out @ 87% CL)

13#sin 2( ) sin( ) CP CPA t m t

The B meson system : A quantum inteferometer for CPV Studies

0 0

0 0

/

/CP S

LCP

B J K

B J K

E.g. for the Golden modes =

mtftBftB

ftBftBtA Dm

cpcp

cpcpcp

sin)(2sin))())((

))())(()(

00

00

u,c,t

0B

u,c,t

W W0

Bd

b

0K

b

c

s

c

d

/J

dJ/

s

sin 2

14#

cp

BaBar:sin2 = 0.722 0.040 (stat) 0.023 (syst)BaBar:sin2 = 0.722 0.040 (stat) 0.023 (syst)

cp

WA: sin2 = 0.685 0.032 (stat)WA: sin2 = 0.685 0.032 (stat)

15#

Past UMD focus: Measurements of BDecaysand determination of

03.009.0

)(02.016.004.0

)(012.0041.0107.0

)(014.0035.0086.0

Average

CLEO

BaBar

BelleAK

Last year - 2004

Evidence Direct CPV ?

Last year - 2004

16#

First observation of Direct CPV in B decays

0

0

BB K

K

0.133 0.030 0.009 CPA

Signal (227 pairs): 1606 51M BB

0 B K 0 B K

Confirmation at ICHEP04

BBAABBARARBBAABBARAR

0.101 0.025 0.005 CPA

Average

4.2

3.9

BelleBelleBelleBelle

BBAABBARARBBAABBARAR

New Belle Result:-0.113+/- 0.022+/- 0.008

-0.115+/- 0.018

17#

18#

For a full Isospin analysis need:

Still some constraint can be set using the measured average Branching fraction:

With WA Br(B and direct CPV

eff | at 90% c.l. 00 ππππ

~ BABA

ππ~

2

10BA

ππ2

10BA

000 ππBA

000 ππ~

BAππ

comes to the rescue: eff | at 90% c.l.

degrees

Measuring

19#

20#

21#

Searches for Deviation from the Standard Model

22#

-sin-sin22

++u,c,t

0B

u,c,t

W W0

Bd

b

B0D*+D*-

B0D*+D*-

Details in D. Roberts’ talk.

Time-dependent CP asymmetryIn SM expect the sine coefficient:

23#

b ss

sd

dg

, ,u c t

0SK

0B

b sd

dd

d

W

g

, ,u c t0SK

0

0B

0B

b

s

s

sd d

, , ( )CPKK

0SK

0B

b

d

s

dd d

0SK

0

, , ( )CPKK

W

New PhysicsNew PhysicsStandard ModelStandard Model

b sss

& & CPV in Bs

& b sdd penguins

Jawahery et al

24#

Directly copied from L. Silvestrini at Lepton-Photon 2005

25#

26#

No Significant deviation from SM yet

27#

28#

29#

Time dependent CPV measurements of the decays (Jawahery,Hulsbergen, Jawahery, Kovalskyi, Simi, Tuggle)

BKsgluinic penguin process)

BKsW penguin process b->s

KsKs’Ks(New effort)

Pioneered the analysis technique that made these measurements possible (Beam constrained Vertexing for modes with no charged partilces at the B vertex.)

Hulsbergen is Co-convener of Radiative penguin analysis working group

UMD’s effort in the study of New Physics search

with b->s measurement

30#

Measuring t for TDCP analysis:

KS

+

-

0

Btag

BCP

Solution: Extrapolate Ks to the beam position Short B lifetime and small transverse motion of B

makes this possible, when Ks’s are measures in Silicon Vertex tracker

Inflated Beam

yx

Beam

0

+ -

Ks

~30 m

~4 m~200 m

0B

Problem: No charged particle in final state

Same technique that we Same technique that we invented for invented for B Ks

31#

The Method Validated using BJ/s events: Measured sinignoring J/in t caclulation

32#

Helicity Flip Suppressed by

~ ms/mb

0B

*RK

mix

ing

*LK

0B

* 2 sin 2 0sK

b

mS

m Expect:

TDCP asymmetry in bs

Within SM: is polarized (bs L ,, b(bar) s(bar) R) (to ~ ms/mb)

Beyond SM may be different

helicity serves as a NP observable

mtCmtSftBftB

ftBftBtA

cpcp

cpcpcp

cossin))())((

))())(()(

00

00

AGS also prescribe the method to measure it via the usual BB interferometery

The value of SK* as a NP observable of course depends on SM uncertainties -

:(A. Atwood, M. Gronau & A. Soni (1997))

33#

TDCP analysis requires modes common to B0 and B0(bar):

The most significant mode:

BK*(890)with Br=(40.1 +/- 2.0) x10-6

with K*K0 K0 Ksx10-6

BK2*(1430) Br=(12.4 +/- 2.4) x10-6 ]

thers and non-resonant BKs Br<2.6 x10-6 )

Also: BKs Br =(8.4 +3.6-3.1) x10-6 (Belle)

B0Ks Br <8.3x 10-6 [B+K+ Br=(3.4+/- 1.0) x10-6 ] Belle

BKs ’ Br (?)

34#

DataBaBar(232 M BB’s)

BK*(Ks 0)

Nsig:157 +/- 16 events

qq_bkg~50 events

NBB_bkg =9+/- 13 events (fit)

~30 (estimated)( 50% from b->s)

BKs 0

Nsig: 59 +/- 13

NBB_bkg=130+/- 40 (fit)

~110 (estimated) (50% from b->s) 275 M BB’s

35#

BaBar(232 M BB’s)

36#

232 M BB-

SK* =-0.21 +/- 0.40 +/- 0.05

CK* = -0.40 +/- 0.23 +/- 0.04

HFAG Average::SK* =-0.13 +/- 0.32 & CK* = -0.31 +/- 0.19 SM: ~0 SM: ~0

275 M BB’s

SKs =-0.21 +/- 0.40 +/- 0.05

CK = -0.40 +/- 0.23 +/- 0.03

SK* =0.01 +/- 0.51 +/- 0.11

CK* = -0.11 +/- 0.33 +/- 0.09

37#

Comments on systematic Errors & Prospects

~ 4 ab-1 For combined BaBar and Belle data at ~2010

~ requires super B factory

38#

UMD contributions to BaBar

• Detector:– Silicon Vertex Tracker: System Management, Operation, Alignment

(Roberts,Chen, Lae) (Also Lillard and Schieck in the past)

– Drift Chamber: Environmental monitoring system (Jawahery, Kovalskyi) (also Bard, Olsen and Farbin in the past )

– BaBar Detector Control: Coordinator (Olsen)

• Reconstruction software:– Tracking: Coordination (Hulsbergen), (Also efficiency and performance

studies: Jawahery & Dallapiccola in the past)

– SVT alignment (Roberts, Lillard, Lae and Schieck)

– Particle Identification: Corrections to DIRC theta-c measurements at high momenta (Dallapiccola, Farbin and Jawahery in the past)

• BaBar computing:– Contribution to Implementation of the New computing model (Lae, Farbin,

Hulsbergen, Roberts)

– Co-chair of BaBar computing model 2 (Jawahery in 2002)

39#

• Analysis:– Study of the decays BDD: Measurement of rates, polarization

and CPV effects. Deviations from SM could signal Physics beyond SM.

– Study of Penguin Dominated decays: BK0

Search for Physics Beyond the SM through deviation of CPV parameters from the SM expectation

– Study of charmless B decays with the goal of measuring the angles and CPV measurements in B

– Study Rare Leptonic Charm decays: De+ e- & D+ -, ..

40#

Other responsibilities & leadership positions• Roberts:

– Co-system manger of Silicon Vertex Tracker (SVT) (June 2003- present)– Co-led and developed the SVT alignment software (with LBL group)

• Jawahery: – Served as Physics analysis coordinator of BaBar(2001-2002)

• Was resident at SLAC Sept. 2001-Sept. 2002

– Initiated and convened the charmless physics group in BaBar– Convener of B&C Physics group (2000) – Served as co-chair of computing model working group (re-design of BaBar computing &

analysis system.) (Fall 2002)– Elected member of BaBar executive board (2003-2006)– Member of BaBar physics advisory group (2003-present)– Member of Roadmap group- studies and planning for super-B experiment at SLAC (2003-

Present). Co-organizer of workshop on super-B at Hawaii (Spring 05)– Member of Physics reach steering committee

• Hulsbergen:– BaBar tracking coordinator (July 2003- Dec. 2004)– Coordinator of BaBar vertexing software and validation studies (Dec. 2002- present)– Co-convener of Radiative Penguin analysis working group (April 2005- present)

• Chen: Operation manager of SVT (Sept. 2004- Present).• Olsen (while at UMD)

– Co-convener of charmless working group– Coordinator of BaBar detector control

41#

Past postdocs and graduate students

•Jim Olsen (Princeton Assist. Professor/ on BaBar)

•Carlo Dallapiccola (U. of Mass Assist. Professor/on BaBar)

•Jochen Schieck (Max Planck Institute)

•Amir Farbin (graduated May 2003- postdoc at UMD 2004 -> U. Of Chicago CERN Fellow in 2005).

•Bram Lillard (Graduated May 2004)

42#

ConclusionWe expect many years of fruitful (& likely) exciting physics with BaBar. Now at around 300

fb-1 going for 1 fb-1.

We will either end up with a very precisely known SM charged weak sector, which could help constrain the phase-space of the models of NP, or find a deviation from SM – to be confirmed directly at LHC.