title gabriella sciolla massachusetts institute of technology representing the babar collaboration...

Title

Gabriella Sciolla Massachusetts Institute of Technology

Representing the BaBar Collaboration

Beauty 2005 - Assisi, June 20-24, 2005

Searching for New Physics at the B factories:

Measurements of sin2 at BaBar

G. Sciolla – M.I.T.Measurements of sin(2) at

BaBar 2

BaBar and PEP-II

BaBar detector 4 collider detector

PEP-II asymmetric B factory 9.0 GeV e- beam 3.1 GeV e+ beam

Peak luminosity 9.1 x 1033 cm-2s-1

Integrated luminosity Delivered: >268 fb-1

e+

e+

Most results in this talk are based on 227 M BB events


BaBar 3

The Beauty of the Unitarity Triangle

Two ways of looking for New Physics: Compare measurement of sides and angles Measure angles in channels with different sensitivity to New

Physics


BaBar 4

The three roads to Charmonium modes:

J/ψ KS, ψ(2S) KS, χc1 KS, ηc KS

J/ψ KL

J/ψ K*0 (K*0 → KS π0)

Open-charm modes: D*+ D*−, D*+ D−, D+ D−

Penguin-dominated modes: φ K0, K+

K− KS, KS KS KS

η′ KS

KS π0, ω KS, f0(980) KS d d

d

b c

d

c

d

d d

s

c

cb


BaBar 5

CP violation in interference between mixing and decays

0 0

0 0

( ( ) ) ( ( ) )( )

( ( ) ) ( ( ) )

sin( ) cos( )

CP CPCP

CP CP

ff

N B t f N B t fA t

N B t f N B t f

S mt C mt

2

2

1

1

f

f

f

C

2

2Im

1

f

f

f

S ff

f

Aqλ

p A

i2e~

0B

0B

CPf

mixin

g

decay

0t t

CPfA

CPfA

(f

)

When only one diagram contributes to the final state: Example: B0 J/KS:

0

Imf

f

C

S

0 0

* * *2

* * *

mix mix

itb td cs cb cd csf

tb td cs cb cd csB decay K

V V V V V Ve

V V V V V V

sin2( ) sin( )CP fA t mt d d

d

c

cb


BaBar 6

Exclusive Breconstruction

How to measure the CP asymmetry

.

e-

Flavor taggingQ=(30.5 0.5)%

(4S)

B0

B0

e-

+

-

e+

+

-

Precise t determination

z~ c t


BaBar 7

The golden mode for sin2: B0 charmonium K0

Theoretically clean Experimentally clean Relatively large BF (~10-4)

CP sample:

mES [GeV]

Phys. Rev. Lett. 94, 161803 (2005)

d d

d

c

cb

s s c s c s

1

J / K , (2s)K , K , K

4370CPN

L

1

J / K

2788CPN

E [MeV]


BaBar 8

CP=+1

CP=-1

sin(2) = 0.722 ± 0.040stat ± 0.023syst

Unbinned maximum likelihood fit to t distribution

Phys. Rev. Lett. 94, 161803 (2005)

The golden mode for sin2: CP fit in B charmonium K0


BaBar 9

SM test in B0 charmonium K0

Compare sides and angles Both BaBar and Belle results

used

Ambiguity resolved measuring sign(cos2) in B0J/K* cos(2)=-0.68 excluded at

86.6%CL [PRD 71 (2005)032005]

Excellent agreement with constraints from the sides Another SM triumph?

.

cos(2β)<0

cos(2β)>0

SM test #2: Compare in various channels

Measurements of angles NOT included in fit


BaBar 10

The bccd trees:

B0 open charm

Tree measures sin2 from bccd transitions Penguin expected to be small in SM (< few %)

D*D*: as large as = 0.6 [Grossman and Worah, 1997]

New Physics could have large effects

u,c,t


BaBar 11

Vector-vector final state: CP-even and CP-odd admixture

Transversity analysis measures fCP-even

The open charm trees:

Recent update: B0 D*+D*-

CCP+ = +0.06 ± 0.17 ± 0.03-SCP+ = 0.75 ± 0.25 ± 0.03

New

BaBar Preliminary

In good agreement with SMfCP+ = (87.5 4.4 0.7)%

* * 391 28D DN


BaBar 12

The open charm trees:

B0 D(*) D

hep-ex/0505092

-S 0.54 0.35 0.07 0.29 0.33 0.07 0.29 0.63 0.06

C 0.09 0.25 0.06 0.17 0.24 0.04 0.11 0.35 0.06

D*+D- D*-D+ D+D-

Updated Updated New


BaBar 13

The key to New Physics:

The Penguin ModesDecays dominated by gluonic penguin diagrams The typical example: B0KS

No tree level contributions In SM, top quark dominates the loop: C~0; S~sin2

Impact of New Physics could be significant New particles could participate in the loop new CPV

phases Low branching fractions

Measure ACP in as many bsqq penguins as possible! φ K0, K+ K− KS, η′ KS, KS π0, KS KS KS, ω KS, f0(980) KS

d d d d

SM NP


BaBar 14

The golden penguin: B0 K0

Combined KS and KL fit:

Phys. Rev. D 71, 091102(R) (2005)

0

0

0.07 0.040.50 0.25

0.00 0.23 0.05K

K

S

C

98 18LKN

114 12SKN


BaBar 15

For non resonant B0K+K-KS decays, CP = 2 feven- 1 feven measured from angular moment analysis of the K+K-

system

Related channel: B0 K+K-KS

0sin2 0.55 0.22 0.04 0.11effstat syst CPK K K

Phys. Rev. D 71, 091102(R) (2005)

452 28SK K K

N

2S

even 2 2S P

Af = = 0.89 ± 0.08 ± 0.06

A A


BaBar 16

A new golden penguin: B0KSKSKS

hep-ex/0502013 (accepted by PRL)

0.32 0.38

0.28 0.35

0.71 0.04

0.34 0.05S S S

S S S

K K K

K K K

S

C

Theoretically clean Penguin dominated CP=+1

eigenstate

Experimentally challenging B decay vertex uses KS pseudo-

particles and beam spot constraint

88 10S S SK K KN


BaBar 17

The silver penguin: B0 ’KS

Relative large BF ~ 6 x 10-5 Theoretically less clean than KS

Tree diagram possible … but Cabibbo and color suppressed…

|S| =|SK-SPenguin|~ 0.01QCDFact 0.1SU(3)

Phys. Rev. Lett. 94, 191802 (2005)

Sη′Ks = 0.30 ± 0.14 ± 0.02

Cη′Ks = −0.21 ± 0.10 ± 0.02

' 804 40SKN


BaBar 18

The challenging penguins:

B00KS, f0KS, KS

B00KS: dominated by tree contribution are non negligible (S ~ 0.1 – 0.2) Experimental challenge: BCP decay vertex reconstruction

(t~1ps)

B0f0KS: In SM dominated by

B0KS: In SM dominated by But tree can be relatively large

b suub sdd

hep-ex/0503011 hep-ex/0408095hep-ex/0503018

B00KS B0f0KS B0KS

-f S 0.35 0.04 +0.95 0.10 +0.50 0.02

C 0.06 0.18 0.03

-0.24 0.31 0.15 -0.56 0.03

0.30 0.33

b sss

b sdd

0.23 0.32

0.34 0.38

0.29 0.27


BaBar 19

“sin2” in penguins: BaBar only

• Although each measurement is compatible with J/KS, a trend is visible

• ’KS has the most significant shift (~2.9 if theory uncertainties neglected)

… but statistical errors are still large…


BaBar 20

• Average of BaBar and Belle results

• Boxes are SM expected ranges for -fSf from Beneke, hep-ph/0505075

• Shift still significant…

SJ/- Spenguins > 3

“sin2” in penguins: BaBar + Belle

Statistical fluctuation or first signs of New Physics?


BaBar 21

Summary and Conclusion

Precision measurements of sin2 in many different channels are a powerful probe for New Physics B0 charmonium K0: our calibration point (sin2~ 0.04) B0 open charm: no smoking guns so far B0 penguin modes: intriguing shifts observed

New Physics or statistical fluctuations? Time and data will tell…

Goals for BaBar luminosity Summer 2006: 500 fb-1

Summer 2008: 1 ab-1


BaBar 22

Backup slides --------------------------------------------------------------------


BaBar 23

Transversity analysis

2

2 2 20 ||

| |

| | | | | |

AR

A A A

• D*+D*- is not a CP eigenstate

• sum of L=0, 2 (CP even) and L=1 (CP odd)

• CP odd fraction R determined by transversity analysis

2 21 d 3 3(1 )sin cos

d cos 4 2

tr trtr

R R


BaBar 24

D*D analysis

SM expectations D+D-

D*D

* *

* *

2*

0 * 0 *

sin(2 ) and sin(2 )

with:

X= 1-C

=difference of strong phases for and

D D D D

D D D D

D D

C C

S X S X

B D D B D D

0

sin2

C

S


BaBar 25

cos and sin fits in penguin modes


BaBar 26

The challenging penguins: B00 KS

In SM these decays are dominated by tree contribution are non negligible

S ~ 0.1 in model dependent QCD calculations S ~ 0.2 in SU(3)

Experimentally challenging BCP decay vtx from KS and beam spot KS tracks with > 3 SVT: t~1ps

Unbinned max likelihood fit:

Nsig = 300 ± 23

0

0

0.30 0.330.35 0.04

0.06 0.18 0.03S

S

K

K

S

C

b suub sdd

hep-ex/0503011


BaBar 27

Two more penguins: B0 f0KS and B0 KS

B0 f0KS dominated by b sss

hep-ex/0408095hep-ex/0503018

10.095.0 23.0 32.0 0

SKfCP S

0153 19

Sf KN

648 ,2

sin cos)980(0

sss

dduussf

B0 ωKS : dominated by b → sddTree contamination can be relatively large

02.050.0 34.0 38.0

SKCP S

092 13

SKN


BaBar 28

The Other Trees:

Recent update: B D*+D*-

Vector-vector final state: CP-even and CP-odd admixture

Transversity analysis measures fodd

fodd = (12.5 4.4 0.7)%

CCP+ = +0.04 ± 0.14 ± 0.02

-SCP+ = 0.65 ± 0.26 +0.09-0.07 ± 0.04

Results presented at Moriond 2005

Good agreement with SM

BaBar Preliminary


BaBar 29

Penguins vs tree

title gabriella sciolla massachusetts institute of technology representing the babar collaboration...

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measurements of sin2

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