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Analysis work by: Rachid Ayad. Sheldon Stone. Jianchun Wang. CBX ... 3 dE/dX consistence for p 0.9. Photon: | cos | 0.707. E9/E25. Not fragment. Angcrt 20 ... – PowerPoint PPT presentation

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Title: Analysis work by:


1
Status of B?D()(4?)- analysis
Jianchun Wang 03/17/00
  • Analysis work by
  • Rachid Ayad
  • Sheldon Stone
  • Jianchun Wang
  • CBX note available
  • /homes/cleo/sls/ds4pi.ps

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 ? Dp?pp-p- , Dwp-
  • D?D?p (D??K-p, K-pp?, K-ppp-)
  • D??D?p? (D??K-p)
  • B ? Dwp- ( D??K-p, D?K-pp)

3
Selection Criteria
  • Track ( slow p only first two)
  • TNG approval
  • Good primary track
  • Impact point (0.005,0.03 for pgt0.25, 0.01,0.05
    for plt0.25)
  • 3? dE/dX consistence for plt0.9
  • Photon
  • cos? lt 0.707
  • E9/E25
  • Not fragment
  • Angcrt gt 20
  • ? (Mass constraint)
  • Multi-bump cut
  • Mass cut 3.0? to 2.5?
  • ?
  • Mass cut 2?
  • Dalitz selection Rlt0.7
  • D
  • Mass cut 2.5?
  • Momentum dependent s
  • D MD-MD 2.5? cut
  • Event R2 lt 0.3
  • B (beam energy constraint)
  • cos?B lt 0.8
  • ?B2 (?MD, ?MD, ?M??)
  • signal ?EB lt 2 ?, ?MB lt 2 ?
  • M sideband 5.203 lt MB lt 5.257
  • E sideband 3? lt ?EB lt 2?

4
The Dp?pp-p- Final State
543?49
358?29
329?41
  • (a) EB sideband 3 5 s
  • (b) EB signal 2s , fit with fixed sideband
    shape

5
Efficiency estimation
  • Slow p ? B efficiency as a function of M(4p)
  • Fit B yield in bins of M(4p)

D??K-p
6
B (B? ? Dp?pp-p-)
  • B (1.72 ? 0.14 ? 0.17)
  • Systematic errors ( 10)
  • 5 for slow p from D
  • 5.4 for p?
  • 2.4 per charged track
  • 3 on background shape
  • 3 on D (2.0) Do (2.3) branching fractions
  • Fitting procedure, 4p decay mechanism dependence
    small

7
The p?pp- Mass Distribution
  • What are the decay mechanisms for the (4p)- final
    state?
  • We first examine the p?pp- mass spectrum
  • 2 combinations per event
  • Three D modes summed together

8
The wp- 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 lt 0.7 used for further study

Rlt1
Rlt0.7
Rlt0.5
9
The Dwp- Final States
  • With selection of ?, the MB plot shows a
    prominent B peak
  • Summed over all three modes
  • N 13715

Events/ 2 MeV
10
The wp- Mass Distribution
Breit-Wigner Mass141637 ? 40247 MeV
Corrected to Mass143237 ?37647
11
Branching ratios for wp- A-
  • B (B? Dwp-) (0.29?0.03?0.03)
  • (B? Dwp-) / (B? D p?pp-p-) (15
    ? 2)
  • (B? DA-) / (B? Dwp-) consistent
    with 100

12
The D? p?pp-p- Final State
  • D??D?p? mode searched
  • Only consider D??K-p mode
  • EB side band (a) and EB signal (b) shown
  • B(B-? D?p?pp-p-) (1.80?0.24?0.20)

19526 events
13
The D?wp- Final State
  • The MB plot shows a prominent B peak
  • 25?6 events
  • B (0.45?0.10?0.05)

14
The wp- Mass Distribution
  • The wp- mass distribution is similar to D final
    state
  • Breit-Wigner fit gives Mass 136775, ?
    439135 MeV

15
Angular Distributions
B?D A- A-? w p- D?D p
w ? p?pp- 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
  • For a spin-0 A , the D w would be fully
    polarized
  • Angles ?D (D to D boost), ?w(normal of w decay
    plane to w 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

16
Angular Distributions
  • Sum of 3 D and 1 D modes
  • For spin-0 A, both D w are fully polarized
  • Data for w decay angle show that A is not spin-0

Spin-0 MC
Spin-0 MC
17
Have Found Dwp- Final States
Dwp-
D?wp-
Events/ 2 MeV
18
The wp- Mass Distribution
D?wp-
Dwp-
Events/ 100 MeV
19
Angular Distributions
B ? D A- A- ? w p-
w ? p? p p- spin 0 0 s
s 1 0 1 0 0
0 helicity 0 0 0 0
? 0 ? 0 0
0
  • qA angle between w in A frame to A boost
    direction
  • qw angle of normal of w decay plane to w boost
  • c angle between planes of A decay and w decay

20
Summary
  • We have seen Dp?pp-p- decays and have measured
    the branching ratio (1.8)
  • About 15 of the decays are Dwp-
  • There is an unexpected wp-enhancement at 141933
    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 ? Dwp- modes, and we will try
    measure JP using this modes
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