16 April 2005 APS 2005 Search for exclusive two body decays of B→D s * h at Belle Luminda Kulasiri University of Cincinnati Outline Motivation Results.

16 April 2005 APS 2005

Search for exclusive two body decaysof B→Ds

*h at Belle

Luminda KulasiriUniversity of Cincinnati

Outline• Motivation• Results• Summary

16 April 2005 APS 2005

Motivation – Ds*+-,Ds

*+0

B-

c

u

Vub

u

u

sW-

b Vcs*

DS

*-

0B0

c

Vub

d

u

sW-

bVcs*

+

d

DS

*-

‘Spectator’ diagram

•Clean Measurement for Vub – no penguins•Model Independent•Not yet seen•Sin(21+3)

V V V

V V V

V V V

ud us ub

cd cs cb

td ts tb

16 April 2005 APS 2005

Motivation – Ds*-K+

B0

Vcb*

Vudd

b DS

*+

K-

Ws

s

u

• W-exchange first seen in B0→ Ds

-K+ (br = (4.6 1.3) x10-5) PRL 89, 231804(2002)

•Not yet seen - sensitivity ~ 5X10-6

- could be seen

•Role of the final state interactions D+-, D00 can turn out to be Ds

*-K+ (B. Block et al. PRL 78, 3999, 1997)

W-exchange+1.2-1.1

16 April 2005 APS 2005

KEKB Accelerator

•Asymmetric Collider with, 8.0 GeV e- x 3.5 GeV e+

•22 mrad crossing angle•Lpeak = 15.33 nb-1s-1

•∫Ldt ~400 fb-1

•Ecm = 10.58 GeV

operates at (4S) resonance

e+e- → (4S) →BB

C.M frame (4S) frame

16 April 2005 APS 2005

Belle Detector

PID(K)L(K)

L(K) L( )

PID( )L( )

L (K) L( )

Silicon VertexDetector (SVD)

Central Drift Chamber (CDC)

KL/µ Detector (KLM)

8GeV e-

3.5 GeV e+

Aerogel Cherenkov cnt. (ACC)

CsI Calorimeter

TOF counter

SC solenoid

Particle ID

Uses info. From CDC+ACC+TOF

PID( )L ( )

L (K) L( )

16 April 2005 APS 2005

Candidate Selection & Background Suppression

Decay Chain

B0→ Ds*+ -,

B0→ Ds*- K+,

B+→ Ds*+ 0

Ds*+→ Ds+

Ds+ → {+, KSK+, K*K+}

→K+K-, KS→+-, K*→K+-

16 April 2005 APS 2005

Candidate Selection & Background Suppression

• Mass selections - 3 • PID > 0.6

M = M(Ds) - M(Ds)

• | M- 0.1438| < 0.020 GeV

• Helicity angle(θh) – for /K* Angle between momentum of DS and momentum of K in (K*) frame.

•Photon-Ecm()>110 MeV, 0 veto

•Pcm(Ds*) < 2.5 GeV

Photon Energy (E)

SignalBg.

GeV |cos(θh)| > 0.3

16 April 2005 APS 2005

Candidate Selection & Background Suppression

B candidate,

–0.05<E<0.05 GeV for h {, K}

–0.10<E<0.05 GeV for h {0}

5.27<Mbc<5.29 GeV/c2

M E Pbc beam ii

2 2( )

E E Ei beami

Ebeam = 5.29 GeV

GeV

GeV/c2

Sign

al M

C

B→Ds*+- (Ds

+→+)

E Vs Mbc

16 April 2005 APS 2005

Candidate Selection & Background Suppression

r

|P | |P | P cos(q )

|P | |P | ; l 1 , 2 , 3 , 4l

i jij

l ij

i jij

Fisher Discriminant – 9 variables

R|P | |P | P cos(q )

|P | |P | ; l 2 , 4l

i hi

l ih

i hi

•cosine of Thrust Angleθth – angle bet. thrust axis of B and thrust axis of rest of the event

•Fox-Wolfram moments

•qr x (QDS) qr -flavor info. of the other B; q = +1/-1 for B0/B0

0< r <1; r- tagging quality

QDS- Ds Charge

•cos(B) B - angle between B flight direction and beam axis

FD

Arb

itrar

y un

its continuum Signal(10K events)

16 April 2005 APS 2005

Fitting (275 Million BB events)

• Fitted distribution M =M(Ds*+) –M(Ds

+)

-Simultaneous fit for the three Ds modes to Br

-binned maximum likelihood

• Signal – Gaussian, mean, width fixed (MC)

• Bg. – linear shape by fitting data ( sig. region excluded), wide cuts

• Significance -

-

2 0ln( ( ) / )maxL L Lmax - max. likelihoodL(0) – max. likelihood if signal is zero

16 April 2005 APS 2005

M and E

(1.64 0.66)x10-5(2.14 0.81)x10-5 (2.43 1.11)x10-5

M

E

DS*+- DS

*-K+ DS*+0

16 April 2005 APS 2005

Yields and Branching fractions(Preliminary)

Mode Rec. eff(%) signal Br(X10-5)

Ds*+- +

KsK+

K*K+

8.470.29

3.73 0.68

3.05 0.36

5.49 3.17

7.32 3.44

4.18 2.68

1.41 0.89

6.16 3.55

2.61 1.70

Combined 2.14 0.81(4.7)

Ds*-K+ +

KsK+

K*K+

6.47 0.24

3.14 0.58

5.20 0.59

3.90 2.44

2.19 1.97

4.04 3.34

1.31 0.89

2.19 2.10

1.36 1.20

combined 1.64 0.66(4.5)

Ds*+0 +

KsK+

K*K+

3.85 0.23

2.45 0.46

3.07 0.39

4.17 2.44

2.25 2.79

0.90 3.39

2.36 1.51

2.89 3.71

0.51 1.95

Combined 2.43 1.11(4.0)

16 April 2005 APS 2005

Systematic Uncertainties

•3 Ds modes – common errors, independent errors separately calculated •Highest errors come from B(Ds→)•MC combines Ds modes

/0 recon.

Br(Ds*→Ds)

NBB

total common

except (br(Ds→))

5%

3%

1%

5.92%

Common errors

16 April 2005 APS 2005

Systematic Uncertainties

Br(Ds) /Br(Ds→)

Br(sub Ds)

Ks

Fitting

MC stat.

Tracking

PID

Common

Total

Ds*+-

+ KsK+ K*K+

0.00 22.2 9.1

1.4 0.4 0.2

- 3.0 -8.20

4.5

3.4

2.9

5.9

12.04

Ds*-K+

+ KsK+ K*K+

0.00 22.2 9.1

1.4 0.4 0.2

- 3.0 -

9.40

6.1

4.5

3.9

5.9

14.25

Ds*+0

+ KsK+ K*K+

0.00 22.2 9.1

1.4 0.4 0.2

- 3.0 -

14.9

8.1

4.4

4.0

5.9

17.34

Independent Errors (%)

separately Br (Ds→) – 25%

16 April 2005 APS 2005

Results & Summary

B r B D

B r B D K

B r B D

C L

S

S

S

( ) ( . . . . ) ( . )

( ) ( . . . . ) ( . )

( ) ( . . . . ) ( . )

. ( @ . . )

*

*

*

0 5

0 5

0 5

5

2 1 4 0 8 1 0 2 6 0 5 4 1 0 4 7

1 6 4 0 6 6 0 2 3 0 4 1 1 0 4 5

2 4 3 1 1 2 0 4 2 0 6 1 1 0 4 0

5 3 3 1 0 9 0 %

•We searched for B→Ds*h events using 275 m BB events

•We have seen evidence for B→Ds*, B→Ds

*K and B→Ds

*0

preliminary

First error – stat. ; Second error = syst. except Br(Ds→)

Third error – syst. from Br(Ds→)

16 April 2005 APS 2005

Backup slides

16 April 2005 APS 2005

Mbc Yield

DS*-K+

10.6±4.9 evts. DS*+-

21.4±5.9 evts.

DS*+0

8.1±5.7 evts.

16 April 2005 APS 2005

Yield in M and E

11.0±4.8 evts19.0±5.7 evts 9.4±5.5 evts

M

E4.48.4 evts.

15.15.6 evts.

8.24.7 evts.

DS*+- DS

*-K+ DS*+0

16 April 2005 APS 2005

Sin(21+3)

s R

RB r B DB r B D

ff

D D

D cs D

Ds

2 2 1 3

0

0

* *

*

*

**

sin( )

tan(( ) *

D* - strong phasec – Cabibbo angle

ff

D

D s

*

*

. . 1 1 0 0 0 2 D. Becirevic, Nucl. Phys. Proc. Suppl. 94, 337 (2001)