WIN’03 Markus Cristinziani, SLAC 1/17

Rare hadronic B decays at BABAR

Markus Cristinziani

WIN’03, Lake Geneva, October 6-11

WIN’03 Markus Cristinziani, SLAC 2/17

Outline

• Measurements of branching fractions and asymmetries ACP for charmless decays by Babar:

B→PP

B→PV

B→VV

• Discuss results which are challenging theory

WIN’03 Markus Cristinziani, SLAC 3/17

Motivation

• Standard Model is good !

• Look for processes where SM is suppressed to be sensitive to new physics

• These are CKM-suppressed decays or

penguin dominated processes

• Measure and interpret as many channel

as possible.

WIN’03 Markus Cristinziani, SLAC 4/17

π+

π-

Processes at the quark level

B0 B0

π+

π-

)cos()sin( tmCtmSA

TreePenguin

)||1/()||1( 22 C

)||1/(Im2 2 S

For a single weak phase: Sππ= sin 2α Cππ= 0

With additional weak phase: S = sin 2eff C≠ 0

|P/T| ~ 0.3

f

f

A

A

p

q

WIN’03 Markus Cristinziani, SLAC 5/17

Direct CP violationIf two distinct strong and weak phases are involved in the decays of the B meson

and its charge conjugate CP asymmetry occurs

)cos()cos(2

)sin()sin(2

12122122

21

12122122

22

)(2

)(1

)(2

)(1

2211

2211

AAAA

AA

AA

AAA

eAeAA

eAeAA

ff

ff

CP

iif

iif : strong phase CP-even

: weak phase CP-odd

WIN’03 Markus Cristinziani, SLAC 6/17

Kinematical Variables

2*2beamES

*BpEm *

beam* EEE B

(mES) 2.6MeV/c2 (E) 20 MeV

Energy substituted mass

WIN’03 Markus Cristinziani, SLAC 7/17

Background suppression

Signalu,d,s,cbackground

Fisher Discriminant

Arb

itra

ry U

nit

s

Monte Carlo

• Event Topology: B’s are produced at rest:B decays are spherical qq events are jet-like

Event shape variables are combined through neural network (NN) or a Fisher discriminant for additional separation

Also tagging information can be used

Maximum likelihood in these variablesBlind Analysis

WIN’03 Markus Cristinziani, SLAC 8/17

B → hh, h=π,K

Mode Br Fract (10-6) Reference ACP (%)

K+ - 17.9 0.9 0.7 PRL 89(2002) 281802 -10 5 2

*K0 + 17.5 1.8 1.3 hep-ex/0206053 FPCP02 -17 10 2

K+ 0 12.8 1.2 1.0 PRL 91(2003) 021801 -9 9 1

*K0 0 10.4 1.5 0.8 hep-ex/0207065 ICHEP02 3 36 9

+ 0 5.5 1.0 0.6 PRL 91(2003) 021801 -3 18 2

+ - 4.7 0.6 0.2 PRL 89(2002) 281802

0 0 2.1 0.6 0.3 hep-ex/0308012 LP03

K+ K- < 0.6

*K+ K0 < 1.3 hep-ex/0206053 FPCP02

*K0 K0 < 1.6

K and BF imply a high penguin contribution

WIN’03 Markus Cristinziani, SLAC 9/17

B → π0π0

Maximum Likelihood fit with qq and B-Background: Nππ= 46

Significance of Signal : 4.2 σ including systematics BF = (2.1 ± 0.6 ± 0.3)x10-6

113 fb-1

WIN’03 Markus Cristinziani, SLAC 10/17

Try to extract α from hereGronau, London PRL 65 (1990) 3381:Branching fractions for are related by isospin

oeff

BBF

BBFeff

48||

)(sin)(

)(200

000

Grossman-Quinn bound

Does not provide a very useful bound Consider → ~ 200

B→ππ0 is pure tree diagramOne common side of the trianglesNeed to measure B and B separately

WIN’03 Markus Cristinziani, SLAC 11/17

B → (ηη’)hMode Br Fract (10-6) Reference ACP (%)

η´ K+ 76.9 3.5 4.4 hep-ex/0303046 4 5 1

η´ K0 60.6 5.6 4.6 hep-ex/0303046

η´ + 2.8 1.3 0.3 hep-ex/0308015

η + 4.2 1.0 0.3 hep-ex/0303039 Moriond -51 20 1

η K+ 2.8 0.8 0.2 hep-ex/0303039 Moriond -32 22 1

η K0 < 4.6 hep-ex/0303039 Moriond

Branching Fractions involving η´ are high

SKB 0

KB

WIN’03 Markus Cristinziani, SLAC 12/17

B → (ηη’)VMode Br Fract (10-6) Reference ACP (%)

η K*+ 25.7 3.8 1.8

hep-ex/0308015 15 14 2

η K*0 19.0 2.2 1.3

hep-ex/0308015 3 11 2

η ρ+ 10.5 3.1 1.3

hep-ex/0308015 6 29 2

η’ K*+ < 12 hep-ex/0308015

η’ K*0 < 6.4 hep-ex/0308015

η’ ρ+ 14.0 5.1 1.9

hep-ex/0308015

η’ φ < 1.0 hep-ex/0309038The different scales in the ηη’ branching fraction are interpreted as an interference of two penguin diagrams (Lipkin Phys.Lett.B 254 (1991) 247)

WIN’03 Markus Cristinziani, SLAC 13/17

B → (ρω)h

• B → ρh updated to 113 fb-1

• B → ρcould provide bounds on through isospin analysis (pentagon relation)

• larger BF than in B → x4)

• smaller |P/T| ratio

• expect CKM suppressed BF(B → ω) > BF(B → ω)

WIN’03 Markus Cristinziani, SLAC 14/17

B → (ρω)hMode Br Fract (10-6) Reference ACP (%)

ρ+ - 22.6 1.8 2.2 hep-ex/0306030 -18 8 3

*ρ+ 0 11.0 1.9 1.9 hep-ex/0307087 EPS 23 16 6

*ρ0 + 9.3 1.0 0.8 hep-ex/0307087 EPS -17 11 2

*ρ0 0 < 2.5 hep-ex/0307087 EPS

ρ+ K- 7.3 1.3 1.3 hep-ex/0306030 28 17 8

ρ0 K+ < 6.2 hep-ex/0303022

ω + 5.4 1.0 0.5 hep-ex/0303040 Moriond 4 17 1

ω 0 < 3

ω K0 5.3 1.4 0.5 hep-ex/0303040 Moriond

ω K+ 5.0 1.0 0.4 hep-ex/0303040 Moriond -5 16 1

WIN’03 Markus Cristinziani, SLAC 15/17

B → VVMode Br Fract (10-6) Reference ACP (%) Long.

Polarization

ρ+ ρ- 27 7 7 hep-ex/0308024 0.99-0.08+0.01

ρ+ ρ0 22.5 5.7 5.8

hep-ex/0307026 -19 23 3 0.97-0.08 +0.03

ρ0 ρ0 < 2.1 hep-ex/0307026

K*+ ρ0 10.6 3.0 2.4

hep-ex/0307026 20 32 4 0.96 -0.15+0.04

N(ρρ) = 93 (>5σ)

WIN’03 Markus Cristinziani, SLAC 16/17

B → φK(*)

Mode Br Fract (10-6) Reference ACP (%)

φ K+ 10.0 0.9 0.5 hep-ex/0303029 4 9 1

φ K0 8.4 1.5 0.5 hep-ex/0309025

φ K*+ 12.7 2.2 1.1 hep-ex/0307026 16 17 3

φ K*0 11.2 1.3 0.8 hep-ex/0307026 4 12 2

Long Polarization

46 12

65 7

The same penguin diagram is dominant in PV and VV cases

“Small”The BF are similar

Pure penguin modes b → sss

Measure sin 2β and a probe for New Physics

WIN’03 Markus Cristinziani, SLAC 17/17

Conclusions

• With 89 (113) fb-1 several charmless decays have been measured

• Most measurements comply nicely with the Standard Model prediction

• Potentially interesting channels include ACP (K+π-), P(φK*), BF(π0π0)

• Need more data to test ACP predictions