analysis work by: rachid ayad sheldon stone jianchun wang cbx note available:...
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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)
03/17/00 Jianchun (JC) Wang 3
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
03/17/00 Jianchun (JC) Wang 4
The DFinal State
35829 54349 32941
(a) EB sideband |3 – 5| (b) EB signal ±2 , fit with fixed sideband shape
DKDK DK
03/17/00 Jianchun (JC) Wang 5
Efficiency estimation Slow + B efficiency as a function of M(4) Fit B yield in bins of M(4)
DK
03/17/00 Jianchun (JC) Wang 6
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
03/17/00 Jianchun (JC) Wang 7
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
03/17/00 Jianchun (JC) Wang 8
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
03/17/00 Jianchun (JC) Wang 9
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
03/17/00 Jianchun (JC) Wang 10
The Mass Distribution
Breit-Wigner: Mass=1416±37 = 402±47 MeV
Corrected to:Mass=1432±37=376±47
03/17/00 Jianchun (JC) Wang 11
Branching ratios for &A
B (B° D) = (0.290.030.03)%
#(B° D) #(B° D) = (15 2)%
#(B° DA) #(B° D)consistent with 100%
03/17/00 Jianchun (JC) Wang 12
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
03/17/00 Jianchun (JC) Wang 13
The DFinal State
The MB plot shows a prominent B peak
256 events
B = (0.450.100.05)%
03/17/00 Jianchun (JC) Wang 14
The Mass Distribution
• The mass distribution is similar to D*+ final state
• Breit-Wigner fit gives: Mass =1367±75, = 439±135 MeV
03/17/00 Jianchun (JC) Wang 15
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
03/17/00 Jianchun (JC) Wang 16
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
03/17/00 Jianchun (JC) Wang 19
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
03/17/00 Jianchun (JC) Wang 20
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
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