of 2
Impro
ved
Measuremen
t of
B
+
!

+

0
and
Determination
of
the
CKM
Angle
We presen
t impro
ved
measuremen
ts of the
branc
hing
fraction
B
, the
longitudinal
polarization
fraction
f
L
, and
the
direct
CP
asymmetry
A
CP
in the
B
meson
deca
y channel
B
+
!

+

0
. The
data
sample
was collected
with
the
B
A
B
AR
detector
at SLA
C.
The
results
are
B
(
B
+
!

+

0
) =
(23
:
7

1
:
4

1
:
4)

10
6
,
f
L
= 0
:
950

0
:
015

0
:
006,
and
A
CP
=
0
:
054

0
:
055

0
:
010,
where
the
uncertain
ties
are
statistical
and
systematic,
resp
ectiv
ely. Based
on
these
results,
we perform
an
isospin
analysis
and
determine
the
CKM
phase
angle
= arg
(
V
td
V

tb
=V
ud
V

ub
) to be (92
:
4
+6
:
0
6
:
5
)

.
PACS numbers: 13.25.Hw,
12.15.Hh,
11.30.Er
2
0
50
100
150
1-CL
0
0.5
1
CL=68%
CL=90%
(deg)
a
-20
0
20
1-CL
0
0.5
1
(deg)
eff
a
a
-
=
Da
FIG.
1: Determination
of
and

from
the
isospin
analysis.
The
solid
(dotted)
curv
es sho
w the
results
using
the
B
+
!

+

0
measuremen
ts presen
ted
here
(prior
to this
analysis).