Polarization fraction &

time-dependent CP analysis of

measured at Belle.

March 2008 – Geneva Swiss Physical Society – Annual meeting

Kim Vervink

Motivationb ccd transition

,

0,1

0,0

= CP eigenvalue

Motivation

: clean because “P/T” is estimated small in the SM.

: clean because 1 CKM amplitude is dominant.

The decay amplitude is CKM suppressed. Any New Physics in the penguins will right away show up, but overall branching fraction is small.

Similarity with the “golden” channel:

First observation of mixing induced CP violation!

very clean measurement of sin2• No hadronic contamination• No contamination from other phases

Difference:

Angular analysis

HistoryBranching fraction

CP odd fraction and CP violation

Luminosity

Belle + BaBar > 1 ab-1

Belle (10 Mar 08)All: ~ 778 fb-1 ,Cont: ~ 68 fb-1 ,Y(5S): ~24 fb-1

ResultsAll preliminary…

Extracting signal

Signal events:

Show signal in:

Angular analysis

Comparison with Babar:

2 B-mesons are produced in a boosted frame

t is measured from vertex positions

B-mesons are entangled: flavor of B1 at time t2 is determined by B2 decay

Decay rates at Belle

Standard method(similar method used for )

lifetime measurement

B-meson lifetime.

: background contribution.

CP violation measurement

Comparison with Babar:

Standard Model prediction in absence of penguin diagrams:

Compatible with SM prediction.

Significance of CPV : 3.8

Summary

• The Standard Model predicts a clean measurement of .

• With a sample of 500 signal events we find:

– Adfa– …

with a significance of 3.8

A result compatible with the Standard Model.

Kim Vervink

Backup slides