Analysis work by:Rachid Ayad

Sheldon StoneJianchun Wang

CBX note available:/homes/cleo/sls/ds4pi.ps

Status of BD(4)analysis

Jianchun Wang03/17/00

03/17/00 Jianchun (JC) Wang 2

Introduction

Why study B D(4)?B D(n) (n = 1, 2, 3)

Charge multiplicity of hadronic B event ~ 5.3

Channels studied:B D, D

DDDK, K, K)

DDDK)

B DDK, DK)

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Selection CriteriaTrack: ( slow π only first two)• TNG approval• Good primary track• Impact point (0.005,0.03 for

p>0.25, 0.01,0.05 for p<0.25)• 3 dE/dX consistence for p<0.9

Photon:• | cos | < 0.707• E9/E25• Not fragment• Angcrt > 20

°: (Mass constraint)• Multi-bump cut• Mass cut: –3.0 to 2.5

:• Mass cut: ± 2• Dalitz selection: R<0.7

D:• Mass cut: ± 2.5• Momentum dependent σ

D*: MD*-MD ± 2.5 cut

Event: R2 < 0.3

B: (beam energy constraint)• | cosB| < 0.8 B

2 (MD*, MD, M)• signal: |EB| < 2 , |MB| < 2 • M sideband: 5.203 < MB < 5.257• E sideband: 3 < |EB| < 2

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The DFinal State

35829 54349 32941

(a) EB sideband |3 – 5| (b) EB signal ±2 , fit with fixed sideband shape

DKDK DK

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Efficiency estimation Slow + B efficiency as a function of M(4) Fit B yield in bins of M(4)

DK

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B (B D)

B = (1.72 0.14 0.17)% Systematic errors ( ~ 10%)

5% for slow + from D*+

5.4% for 2.4% per charged track3% on background shape3% on D*+ (2.0%) & Do (2.3%) branching fractions

Fitting procedure, 4 decay mechanism dependence small

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The Mass Distribution

What are the decay mechanisms for the (4) final state?

We first examine the mass spectrum

2 combinations per event

Three Dmodes summed together

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The Final State Smaller binning in

mass region shown

R represents the location of event in Dalitz plane, the small R is, the more close it is to center

R < 0.7 used for further study

R<1

R<0.7

R<0.5

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The DFinal States

With selection of , the MB plot shows a prominent B peak

Summed over all three modes

N = 137±15

Eve

nts/

2 M

eV

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The Mass Distribution

Breit-Wigner: Mass=1416±37 = 402±47 MeV

Corrected to:Mass=1432±37=376±47

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Branching ratios for &A

B (B° D) = (0.290.030.03)%

#(B° D) #(B° D) = (15 2)%

#(B° DA) #(B° D)consistent with 100%

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The D Final State

• DDmode searched

• Only consider DK mode

• EB side band (a) and EB signal (b) shown

• B(B D) = (1.800.240.20)%

195±26 events

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The DFinal State

The MB plot shows a prominent B peak

256 events

B = (0.450.100.05)%

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The Mass Distribution

• The mass distribution is similar to D*+ final state

• Breit-Wigner fit gives: Mass =1367±75, = 439±135 MeV

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Angular Distributions

• For a spin-0 A , the D* & would be fully polarized

• Angles D* (D to D* boost), (normal of decay plane to boost) can be used

• For spin-1, 2 or higher A, the D* could also be fully polarized

• Only information is if we can exclude full polarization, then we can rule out spin-0

BDAADD

spin 0 1 s s 1 0 1 0 0 1 0 0 0

helicity 0 2 2 3 0 0 0 3 0 0 0

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Angular Distributions

• Sum of 3 D and 1 D° modes

• For spin-0 A, both D* & are fully polarized

• Data for decay angle show that A is not spin-0

Spin-0 MC Spin-0 MC

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Have Found D Final StatesE

vent

s/ 2

MeV

D D

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The Mass Distribution E

vent

s/ 1

00 M

eV

D D

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Angular Distributions

angle between in A frame to A boost direction

angle of normal of decay plane to boost

angle between planes of A decay and decay

B D AA

spin 0 0 s s 1 0 1 0 0 0

helicity 0 0 0 0 0 0 0 0

JP=0

L 1/2 3/2 cos2 1

JP=1

TL

2a1 3/4 sin2

+ a0 3/2 cos2

2a1 3/4 sin2

+ a0 3/2 cos2

2a1 2cos2+ a0

JP=1

T 3/4 sin2 3/4 sin2 2sin2

JP=2

T 15/4 sin2 cos2 3/4 sin2 2sin2

JP=2

TL

2a1 15/4 sin2 cos2

+ a0 5/8 (3cos2-1)22a1 3/4 sin2

+ a0 3/2 cos2

2a1 2cos2+ a0

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Summary• We have seen D decays and have measured

the branching ratio (~1.8%)

• About 15% of the decays are D

• There is an unexpected enhancement at 1419±33 MeV that is 382 ±44 MeV wide, this resonance is still under study, it can also be a non-qq state, or a mixture of several resonance

• We discover B D modes, and we will try measure JP using this modes