Analysis work by:

1
Study of B?D??-
Jianchun Wang 05/12/00

• Analysis work by
• Marina Artuso
• Sheldon Stone
• Jianchun Wang
• CBX note available
• /homes/cleo/sls/dompi.ps

2
Introduction

• What we have for B ? D()(4?)- (3/14 PTA)
• B ? Dp?pp-p- ( 1.72?0.14?0.24, 1.80?0.24?0.25
  )
• Dwp- ( 0.29?0.03?0.04,
  0.45?0.10?0.07 )
• Possible wp- resonance(A) at 1419?33, ?382?44
  MeV
• Spin 0 is ruled out
• Why B ? D??- ( Do ? K-?, D ? K-? ? )
• First observation, branch ratio is already
  interesting
• Spin-0 D ? easier to identify A

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? (20MeV)
• Dalitz selection Rlt0.7
• D
• Mass cut 2.5?
• Momentum dependent ?
• Event R2 lt 0.3
• B (beam energy constraint)
• cos?B lt 0.5
• ?B2 (?MD, ?M?, ?M??)
• signal ?EB lt 2 ?, ?MB lt 2 ?
• M sideband 5.203 lt MB lt 5.257
• E sideband 7? lt ?EB lt 3?

4
The DEB-MB Distribution
5
?EB Distribution
6
?b2 Distribution
7
The Dwp- Final State
8
The w Side bands

• The w side bands 3s lt Mppp-Mw lt 5s
• Only D?wp- channel shown

9
Reconstruction Efficiency
10
Br (B ? Dwp-)

• Efficiency dependence on Mwp and decay angles
  considered (small)
• Br (B- ? D?wp-) (0.41?0.07?0.04) Br (B? ?
  Dwp-) (0.28?0.05?0.03)
• Systematic errors ( 10)
• 5.4 for p?
• 2.2 per charged track
• 5.5 on background shape
• Miscellaneous

11
The wp- Mass Distribution
Breit-Wigner Mass 1418?26 ?388?44 MeV

• Right plot derived from fit of MB distribution
  for each bin
• Mass window (1.1-1.7 GeV) applied for further
  study

12
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

13
Angular dependent efficiency
Slightly dependent, correction made
14
The Angular Distributions
For 1 and 2-, the langitudinal ratio a0 is
floating
15
The c2 of Angular Fit
Remind c2 / ndof 1.0 ? 40
16
Summary

• We have observed Dwp- decays and measured the
  branching ratio (0.41 for B, 0.28 for B)
• There is wp- enhancement at 141826 MeV that is
  38844 MeV wide, which is consistent with our
  previous observation in Dwp- modes.
• Angular distributions are studied, JP 1- is
  favored
• The resonance A is most likely r(1440)
• Combine two CBX together